Introduce a generic pubsub mod in cdk-common (#1098)

* pubsub: consolidate into Spec, adopt Arc<SubscriptionId>, and wire through  wallet/mint/WS/FFI

Refactor the pub/sub engine to a single Spec trait, move Event alongside it,
and propagate Arc-backed subscription IDs across the stack. This simplifies
generics, clarifies responsibilities, and preserves coalescing +
latest-on-subscribe semantics.

-   **Single source of truth:** `Spec` owns `Topic`, `Event`, `SubscriptionId`,
    `Context`, new_instance, and fetch_events.
-   **Lean & explicit API:** Remove Topic trait split;
    `Subscriber::send(Event)` carries sub-ID internally.
-   **Performance/ergonomics:** `Arc<SubscriptionId>` avoids heavy clones and
    makes channel/task hops trivial.

-   Introduce `pub_sub/typ.rs` with:
    -   trait `Spec`
    -   trait `Event` colocated with Spec.
-   Remove `pub_sub/event.rs` fold `Event` into `typ.rs`.
-   Make `Pubsub<S>` generic over `Spec` and store `Arc<S>`.
-   The subscriber holds `Arc<SubscriptionId>` and deduplicates the latest
    entry per subscription.
-   SubscriptionRequest: rename SubscriptionName → SubscriptionId; return
    `Arc<...>` from `subscription_name()`.
-   Remote consumer (Transport) now parameterized by `Spec`; control types
    updated:
    -   `StreamCtrl<S>`, `SubscribeMessage<S>`, internal caches keyed by
        `S::Topic`.
-   Mint/wallet:
    -   Mint: `MintPubSubSpec` (Context = `DynMintDatabase`),
        `PubSubManager(Pubsub<MintPubSubSpec>)`.
    -   Wallet: lightweight MintSubTopics Spec with `Context = ()`.
-   IDs go Arc end-to-end:
    -   cdk-axum WS maps `HashMap<Arc<SubId>, JoinHandle<()>>`, publisher sends
        `(Arc<SubId>, NotificationPayload)`.
    -   `subscription::{Params, WalletParams}` now use `Arc<...>`.
    -   cdk-ffi conversions & wallet glue updated.
    -   Integration tests updated for new types.

-   Coalescing unchanged: multiple local subs to the same topic are combined
    into a single remote sub.
-   Backfill via `Spec::fetch_events(topics, Subscriber)`; Subscriber enforces
    latest-only dedupe per subscription.

**Result:** a slimmer, more maintainable pub/sub core that’s easier to embed
across mint, wallet, transports, and FFI without sacrificing performance or
semantics.


---------

Co-authored-by: thesimplekid <tsk@thesimplekid.com>

.github/workflows/ci.yml

@@ -490,6 +490,16 @@ jobs:
     steps:
       - name: checkout
         uses: actions/checkout@v4
+      - name: Free Disk Space (Ubuntu)
+        uses: jlumbroso/free-disk-space@main
+        with:
+          tool-cache: false
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v17
       - name: Nix Cache

Cargo.toml

@@ -70,7 +70,7 @@ futures = { version = "0.3.28", default-features = false, features = ["async-awa
 lightning-invoice = { version = "0.33.0", features = ["serde", "std"] }
 lightning = { version = "0.1.2", default-features = false, features = ["std"]}
 ldk-node = "0.6.2"
-serde = { version = "1", features = ["derive"] }
+serde = { version = "1", features = ["derive", "rc"] }
 serde_json = "1"
 thiserror = { version = "2" }
 tokio = { version = "1", default-features = false, features = ["rt", "macros", "test-util", "sync"] }

crates/cashu/Cargo.toml

@@ -13,13 +13,13 @@ readme = "README.md"
 [features]
 default = ["mint", "wallet", "auth"]
 swagger = ["dep:utoipa"]
-mint = ["dep:uuid"]
+mint = []
 wallet = []
 auth = ["dep:strum", "dep:strum_macros", "dep:regex"]
 bench = []
 
 [dependencies]
-uuid = { workspace = true, optional = true }
+uuid.workspace = true
 bitcoin.workspace = true
 cbor-diag.workspace = true
 ciborium.workspace = true

crates/cashu/src/lib.rs

@@ -16,7 +16,6 @@ pub use self::mint_url::MintUrl;
 pub use self::nuts::*;
 pub use self::util::SECP256K1;
 
-#[cfg(feature = "mint")]
 pub mod quote_id;
 
 #[doc(hidden)]

crates/cashu/src/nuts/nut17/mod.rs

@@ -2,13 +2,11 @@
 use serde::de::DeserializeOwned;
 use serde::{Deserialize, Serialize};
 
-#[cfg(feature = "mint")]
 use super::PublicKey;
 use crate::nuts::{
     CurrencyUnit, MeltQuoteBolt11Response, MintQuoteBolt11Response, PaymentMethod, ProofState,
 };
-#[cfg(feature = "mint")]
+use crate::quote_id::QuoteIdError;
-use crate::quote_id::{QuoteId, QuoteIdError};
 use crate::MintQuoteBolt12Response;
 
 pub mod ws;
@@ -109,7 +107,10 @@ pub enum WsCommand {
     ProofState,
 }
 
-impl<T> From<MintQuoteBolt12Response<T>> for NotificationPayload<T> {
+impl<T> From<MintQuoteBolt12Response<T>> for NotificationPayload<T>
+where
+    T: Clone,
+{
     fn from(mint_quote: MintQuoteBolt12Response<T>) -> NotificationPayload<T> {
         NotificationPayload::MintQuoteBolt12Response(mint_quote)
     }
@@ -119,7 +120,10 @@ impl<T> From<MintQuoteBolt12Response<T>> for NotificationPayload<T> {
 #[serde(bound = "T: Serialize + DeserializeOwned")]
 #[serde(untagged)]
 /// Subscription response
-pub enum NotificationPayload<T> {
+pub enum NotificationPayload<T>
+where
+    T: Clone,
+{
     /// Proof State
     ProofState(ProofState),
     /// Melt Quote Bolt11 Response
@@ -130,38 +134,23 @@ pub enum NotificationPayload<T> {
     MintQuoteBolt12Response(MintQuoteBolt12Response<T>),
 }
 
-impl<T> From<ProofState> for NotificationPayload<T> {
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Deserialize, Hash, Serialize)]
-    fn from(proof_state: ProofState) -> NotificationPayload<T> {
+#[serde(bound = "T: Serialize + DeserializeOwned")]
-        NotificationPayload::ProofState(proof_state)
-    }
-}
-
-impl<T> From<MeltQuoteBolt11Response<T>> for NotificationPayload<T> {
-    fn from(melt_quote: MeltQuoteBolt11Response<T>) -> NotificationPayload<T> {
-        NotificationPayload::MeltQuoteBolt11Response(melt_quote)
-    }
-}
-
-impl<T> From<MintQuoteBolt11Response<T>> for NotificationPayload<T> {
-    fn from(mint_quote: MintQuoteBolt11Response<T>) -> NotificationPayload<T> {
-        NotificationPayload::MintQuoteBolt11Response(mint_quote)
-    }
-}
-
-#[cfg(feature = "mint")]
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
 /// A parsed notification
-pub enum Notification {
+pub enum NotificationId<T>
+where
+    T: Clone,
+{
     /// ProofState id is a Pubkey
     ProofState(PublicKey),
     /// MeltQuote id is an QuoteId
-    MeltQuoteBolt11(QuoteId),
+    MeltQuoteBolt11(T),
     /// MintQuote id is an QuoteId
-    MintQuoteBolt11(QuoteId),
+    MintQuoteBolt11(T),
     /// MintQuote id is an QuoteId
-    MintQuoteBolt12(QuoteId),
+    MintQuoteBolt12(T),
     /// MintQuote id is an QuoteId
-    MeltQuoteBolt12(QuoteId),
+    MeltQuoteBolt12(T),
 }
 
 /// Kind
@@ -187,7 +176,6 @@ impl<I> AsRef<I> for Params<I> {
 /// Parsing error
 #[derive(thiserror::Error, Debug)]
 pub enum Error {
-    #[cfg(feature = "mint")]
     #[error("Uuid Error: {0}")]
     /// Uuid Error
     QuoteId(#[from] QuoteIdError),

crates/cashu/src/nuts/nut17/ws.rs

@@ -36,7 +36,10 @@ pub struct WsUnsubscribeResponse<I> {
 /// subscription
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(bound = "T: Serialize + DeserializeOwned, I: Serialize + DeserializeOwned")]
-pub struct NotificationInner<T, I> {
+pub struct NotificationInner<T, I>
+where
+    T: Clone,
+{
     /// The subscription ID
     #[serde(rename = "subId")]
     pub sub_id: I,

crates/cdk-axum/src/ws/mod.rs

@@ -1,9 +1,10 @@
 use std::collections::HashMap;
+use std::sync::Arc;
 
 use axum::extract::ws::{CloseFrame, Message, WebSocket};
 use cdk::mint::QuoteId;
 use cdk::nuts::nut17::NotificationPayload;
-use cdk::pub_sub::SubId;
+use cdk::subscription::SubId;
 use cdk::ws::{
     notification_to_ws_message, NotificationInner, WsErrorBody, WsMessageOrResponse,
     WsMethodRequest, WsRequest,
@@ -36,8 +37,8 @@ pub use error::WsError;
 
 pub struct WsContext {
     state: MintState,
-    subscriptions: HashMap<SubId, tokio::task::JoinHandle<()>>,
+    subscriptions: HashMap<Arc<SubId>, tokio::task::JoinHandle<()>>,
-    publisher: mpsc::Sender<(SubId, NotificationPayload<QuoteId>)>,
+    publisher: mpsc::Sender<(Arc<SubId>, NotificationPayload<QuoteId>)>,
 }
 
 /// Main function for websocket connections

crates/cdk-axum/src/ws/subscribe.rs

@@ -1,4 +1,4 @@
-use cdk::subscription::{IndexableParams, Params};
+use cdk::subscription::Params;
 use cdk::ws::{WsResponseResult, WsSubscribeResponse};
 
 use super::{WsContext, WsError};
@@ -15,22 +15,20 @@ pub(crate) async fn handle(
         return Err(WsError::InvalidParams);
     }
 
-    let params: IndexableParams = params.into();
-
     let mut subscription = context
         .state
         .mint
         .pubsub_manager()
-        .try_subscribe(params)
+        .subscribe(params)
-        .await
         .map_err(|_| WsError::ParseError)?;
 
     let publisher = context.publisher.clone();
+    let sub_id_for_sender = sub_id.clone();
     context.subscriptions.insert(
         sub_id.clone(),
         tokio::spawn(async move {
             while let Some(response) = subscription.recv().await {
-                let _ = publisher.send(response).await;
+                let _ = publisher.try_send((sub_id_for_sender.clone(), response.into_inner()));
             }
         }),
     );

crates/cdk-common/Cargo.toml

@@ -40,10 +40,16 @@ anyhow.workspace = true
 serde_json.workspace = true
 serde_with.workspace = true
 web-time.workspace = true
+tokio.workspace = true
+parking_lot = "0.12.5"
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 uuid = { workspace = true, features = ["js"], optional = true }
+getrandom = { version = "0.2", features = ["js"] }
+wasm-bindgen = "0.2"
+wasm-bindgen-futures = "0.4"
 
 [dev-dependencies]
 rand.workspace = true
 bip39.workspace = true
+wasm-bindgen-test = "0.3"

crates/cdk-common/src/lib.rs

@@ -33,3 +33,5 @@ pub use cashu::nuts::{self, *};
 pub use cashu::quote_id::{self, *};
 pub use cashu::{dhke, ensure_cdk, mint_url, secret, util, SECP256K1};
 pub use error::Error;
+/// Re-export parking_lot for reuse
+pub use parking_lot;

crates/cdk-common/src/pub_sub/error.rs

@@ -0,0 +1,44 @@
+//! Error types for the pub-sub module.
+
+use tokio::sync::mpsc::error::TrySendError;
+
+#[derive(thiserror::Error, Debug)]
+/// Error
+pub enum Error {
+    /// No subscription found
+    #[error("Subscription not found")]
+    NoSubscription,
+
+    /// Parsing error
+    #[error("Parsing Error {0}")]
+    ParsingError(String),
+
+    /// Internal error
+    #[error("Internal")]
+    Internal(Box<dyn std::error::Error + Send + Sync>),
+
+    /// Internal error
+    #[error("Internal error {0}")]
+    InternalStr(String),
+
+    /// Not supported
+    #[error("Not supported")]
+    NotSupported,
+
+    /// Channel is full
+    #[error("Channel is full")]
+    ChannelFull,
+
+    /// Channel is closed
+    #[error("Channel is close")]
+    ChannelClosed,
+}
+
+impl<T> From<TrySendError<T>> for Error {
+    fn from(value: TrySendError<T>) -> Self {
+        match value {
+            TrySendError::Closed(_) => Error::ChannelClosed,
+            TrySendError::Full(_) => Error::ChannelFull,
+        }
+    }
+}

crates/cdk-common/src/pub_sub/index.rs

@@ -1,161 +0,0 @@
-//! WS Index
-
-use std::fmt::Debug;
-use std::ops::Deref;
-use std::sync::atomic::{AtomicUsize, Ordering};
-
-use super::SubId;
-
-/// Indexable trait
-pub trait Indexable {
-    /// The type of the index, it is unknown and it is up to the Manager's
-    /// generic type
-    type Type: PartialOrd + Ord + Send + Sync + Debug;
-
-    /// To indexes
-    fn to_indexes(&self) -> Vec<Index<Self::Type>>;
-}
-
-#[derive(Debug, Ord, PartialOrd, PartialEq, Eq, Clone)]
-/// Index
-///
-/// The Index is a sorted structure that is used to quickly find matches
-///
-/// The counter is used to make sure each Index is unique, even if the prefix
-/// are the same, and also to make sure that earlier indexes matches first
-pub struct Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    prefix: T,
-    counter: SubscriptionGlobalId,
-    id: super::SubId,
-}
-
-impl<T> From<&Index<T>> for super::SubId
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    fn from(val: &Index<T>) -> Self {
-        val.id.clone()
-    }
-}
-
-impl<T> Deref for Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    type Target = T;
-
-    fn deref(&self) -> &Self::Target {
-        &self.prefix
-    }
-}
-
-impl<T> Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    /// Compare the
-    pub fn cmp_prefix(&self, other: &Index<T>) -> std::cmp::Ordering {
-        self.prefix.cmp(&other.prefix)
-    }
-
-    /// Returns a globally unique id for the Index
-    pub fn unique_id(&self) -> usize {
-        self.counter.0
-    }
-}
-
-impl<T> From<(T, SubId, SubscriptionGlobalId)> for Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    fn from((prefix, id, counter): (T, SubId, SubscriptionGlobalId)) -> Self {
-        Self {
-            prefix,
-            id,
-            counter,
-        }
-    }
-}
-
-impl<T> From<(T, SubId)> for Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    fn from((prefix, id): (T, SubId)) -> Self {
-        Self {
-            prefix,
-            id,
-            counter: Default::default(),
-        }
-    }
-}
-
-impl<T> From<T> for Index<T>
-where
-    T: PartialOrd + Ord + Send + Sync + Debug,
-{
-    fn from(prefix: T) -> Self {
-        Self {
-            prefix,
-            id: Default::default(),
-            counter: SubscriptionGlobalId(0),
-        }
-    }
-}
-
-static COUNTER: AtomicUsize = AtomicUsize::new(0);
-
-/// Dummy type
-///
-/// This is only use so each Index is unique, with the same prefix.
-///
-/// The prefix is used to leverage the BTree to find things quickly, but each
-/// entry/key must be unique, so we use this dummy type to make sure each Index
-/// is unique.
-///
-/// Unique is also used to make sure that the indexes are sorted by creation order
-#[derive(Debug, Ord, PartialOrd, PartialEq, Eq, Clone, Copy)]
-pub struct SubscriptionGlobalId(usize);
-
-impl Default for SubscriptionGlobalId {
-    fn default() -> Self {
-        Self(COUNTER.fetch_add(1, Ordering::Relaxed))
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_index_from_tuple() {
-        let sub_id = SubId::from("test_sub_id");
-        let prefix = "test_prefix";
-        let index: Index<&str> = Index::from((prefix, sub_id.clone()));
-        assert_eq!(index.prefix, "test_prefix");
-        assert_eq!(index.id, sub_id);
-    }
-
-    #[test]
-    fn test_index_cmp_prefix() {
-        let sub_id = SubId::from("test_sub_id");
-        let index1: Index<&str> = Index::from(("a", sub_id.clone()));
-        let index2: Index<&str> = Index::from(("b", sub_id.clone()));
-        assert_eq!(index1.cmp_prefix(&index2), std::cmp::Ordering::Less);
-    }
-
-    #[test]
-    fn test_sub_id_from_str() {
-        let sub_id = SubId::from("test_sub_id");
-        assert_eq!(sub_id.0, "test_sub_id");
-    }
-
-    #[test]
-    fn test_sub_id_deref() {
-        let sub_id = SubId::from("test_sub_id");
-        assert_eq!(&*sub_id, "test_sub_id");
-    }
-}

crates/cdk-common/src/pub_sub/mod.rs

@@ -1,77 +1,180 @@
-//! Publish–subscribe pattern.
+//! Publish/Subscribe core
 //!
-//! This is a generic implementation for
+//! This module defines the transport-agnostic pub/sub primitives used by both
-//! [NUT-17](<https://github.com/cashubtc/nuts/blob/main/17.md>) with a type
+//! mint and wallet components. The design prioritizes:
-//! agnostic Publish-subscribe manager.
 //!
-//! The manager has a method for subscribers to subscribe to events with a
+//! - **Request coalescing**: multiple local subscribers to the same remote topic
-//! generic type that must be converted to a vector of indexes.
+//!   result in a single upstream subscription, with local fan‑out.
+//! - **Latest-on-subscribe** (NUT-17): on (re)subscription, the most recent event
+//!   is fetched and delivered before streaming new ones.
+//! - **Backpressure-aware delivery**: bounded channels + drop policies prevent
+//!   a slow consumer from stalling the whole pipeline.
+//! - **Resilience**: automatic reconnect with exponential backoff; WebSocket
+//!   streaming when available, HTTP long-poll fallback otherwise.
 //!
-//! Events are also generic that should implement the `Indexable` trait.
+//! Terms used throughout the module:
-use std::fmt::Debug;
+//! - **Event**: a domain object that maps to one or more `Topic`s via `Event::get_topics`.
-use std::ops::Deref;
+//! - **Topic**: an index/type that defines storage and matching semantics.
-use std::str::FromStr;
+//! - **SubscriptionRequest**: a domain-specific filter that can be converted into
+//!   low-level transport messages (e.g., WebSocket subscribe frames).
+//! - **Spec**: type bundle tying `Event`, `Topic`, `SubscriptionId`, and serialization.
+
+mod error;
+mod pubsub;
+pub mod remote_consumer;
+mod subscriber;
+mod types;
+
+pub use self::error::Error;
+pub use self::pubsub::Pubsub;
+pub use self::subscriber::{Subscriber, SubscriptionRequest};
+pub use self::types::*;
+
+#[cfg(test)]
+mod test {
+    use std::collections::HashMap;
+    use std::sync::{Arc, RwLock};
 
     use serde::{Deserialize, Serialize};
 
-pub mod index;
+    use super::subscriber::SubscriptionRequest;
+    use super::{Error, Event, Pubsub, Spec, Subscriber};
 
-/// Default size of the remove channel
+    #[derive(Clone, Debug, Serialize, Eq, PartialEq, Deserialize)]
-pub const DEFAULT_REMOVE_SIZE: usize = 10_000;
+    pub struct Message {
+        pub foo: u64,
+        pub bar: u64,
+    }
 
-/// Default channel size for subscription buffering
+    #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Deserialize, Serialize)]
-pub const DEFAULT_CHANNEL_SIZE: usize = 10;
+    pub enum IndexTest {
+        Foo(u64),
+        Bar(u64),
+    }
+
+    impl Event for Message {
+        type Topic = IndexTest;
+
+        fn get_topics(&self) -> Vec<Self::Topic> {
+            vec![IndexTest::Foo(self.foo), IndexTest::Bar(self.bar)]
+        }
+    }
+
+    pub struct CustomPubSub {
+        pub storage: Arc<RwLock<HashMap<IndexTest, Message>>>,
+    }
 
     #[async_trait::async_trait]
-/// On New Subscription trait
+    impl Spec for CustomPubSub {
-///
+        type Topic = IndexTest;
-/// This trait is optional and it is used to notify the application when a new
-/// subscription is created. This is useful when the application needs to send
-/// the initial state to the subscriber upon subscription
-pub trait OnNewSubscription {
-    /// Index type
-    type Index;
-    /// Subscription event type
-    type Event;
 
-    /// Called when a new subscription is created
+        type Event = Message;
-    async fn on_new_subscription(
+
-        &self,
+        type SubscriptionId = String;
-        request: &[&Self::Index],
+
-    ) -> Result<Vec<Self::Event>, String>;
+        type Context = ();
+
+        fn new_instance(_context: Self::Context) -> Arc<Self>
+        where
+            Self: Sized,
+        {
+            Arc::new(Self {
+                storage: Default::default(),
+            })
         }
 
-/// Subscription Id wrapper
+        async fn fetch_events(
-///
+            self: &Arc<Self>,
-/// This is the place to add some sane default (like a max length) to the
+            topics: Vec<<Self::Event as Event>::Topic>,
-/// subscription ID
+            reply_to: Subscriber<Self>,
-#[derive(Debug, Clone, Default, Eq, PartialEq, Ord, PartialOrd, Hash, Serialize, Deserialize)]
+        ) where
-pub struct SubId(String);
+            Self: Sized,
+        {
+            let storage = self.storage.read().unwrap();
 
-impl From<&str> for SubId {
+            for index in topics {
-    fn from(s: &str) -> Self {
+                if let Some(value) = storage.get(&index) {
-        Self(s.to_string())
+                    let _ = reply_to.send(value.clone());
+                }
+            }
         }
     }
 
-impl From<String> for SubId {
+    #[derive(Debug, Clone)]
-    fn from(s: String) -> Self {
+    pub enum SubscriptionReq {
-        Self(s)
+        Foo(u64),
+        Bar(u64),
+    }
+
+    impl SubscriptionRequest for SubscriptionReq {
+        type Topic = IndexTest;
+
+        type SubscriptionId = String;
+
+        fn try_get_topics(&self) -> Result<Vec<Self::Topic>, Error> {
+            Ok(vec![match self {
+                SubscriptionReq::Bar(n) => IndexTest::Bar(*n),
+                SubscriptionReq::Foo(n) => IndexTest::Foo(*n),
+            }])
+        }
+
+        fn subscription_name(&self) -> Arc<Self::SubscriptionId> {
+            Arc::new("test".to_owned())
         }
     }
 
-impl FromStr for SubId {
+    #[tokio::test]
-    type Err = ();
+    async fn delivery_twice_realtime() {
+        let pubsub = Pubsub::new(CustomPubSub::new_instance(()));
 
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        assert_eq!(pubsub.active_subscribers(), 0);
-        Ok(Self(s.to_string()))
+
-    }
+        let mut subscriber = pubsub.subscribe(SubscriptionReq::Foo(2)).unwrap();
+
+        assert_eq!(pubsub.active_subscribers(), 1);
+
+        let _ = pubsub.publish_now(Message { foo: 2, bar: 1 });
+        let _ = pubsub.publish_now(Message { foo: 2, bar: 2 });
+
+        assert_eq!(subscriber.recv().await.map(|x| x.bar), Some(1));
+        assert_eq!(subscriber.recv().await.map(|x| x.bar), Some(2));
+        assert!(subscriber.try_recv().is_none());
+
+        drop(subscriber);
+
+        assert_eq!(pubsub.active_subscribers(), 0);
     }
 
-impl Deref for SubId {
+    #[tokio::test]
-    type Target = String;
+    async fn read_from_storage() {
+        let x = CustomPubSub::new_instance(());
+        let storage = x.storage.clone();
 
-    fn deref(&self) -> &Self::Target {
+        let pubsub = Pubsub::new(x);
-        &self.0
+
+        {
+            // set previous value
+            let mut s = storage.write().unwrap();
+            s.insert(IndexTest::Bar(2), Message { foo: 3, bar: 2 });
+        }
+
+        let mut subscriber = pubsub.subscribe(SubscriptionReq::Bar(2)).unwrap();
+
+        // Just should receive the latest
+        assert_eq!(subscriber.recv().await.map(|x| x.foo), Some(3));
+
+        // realtime delivery test
+        let _ = pubsub.publish_now(Message { foo: 1, bar: 2 });
+        assert_eq!(subscriber.recv().await.map(|x| x.foo), Some(1));
+
+        {
+            // set previous value
+            let mut s = storage.write().unwrap();
+            s.insert(IndexTest::Bar(2), Message { foo: 1, bar: 2 });
+        }
+
+        // new subscription should only get the latest state (it is up to the Topic trait)
+        let mut y = pubsub.subscribe(SubscriptionReq::Bar(2)).unwrap();
+        assert_eq!(y.recv().await.map(|x| x.foo), Some(1));
     }
 }

crates/cdk-common/src/pub_sub/pubsub.rs

@@ -0,0 +1,185 @@
+//! Pub-sub producer
+
+use std::cmp::Ordering;
+use std::collections::{BTreeMap, HashSet};
+use std::sync::atomic::AtomicUsize;
+use std::sync::Arc;
+
+use parking_lot::RwLock;
+use tokio::sync::mpsc;
+
+use super::subscriber::{ActiveSubscription, SubscriptionRequest};
+use super::{Error, Event, Spec, Subscriber};
+
+/// Default channel size for subscription buffering
+pub const DEFAULT_CHANNEL_SIZE: usize = 10_000;
+
+/// Subscriber Receiver
+pub type SubReceiver<S> = mpsc::Receiver<(Arc<<S as Spec>::SubscriptionId>, <S as Spec>::Event)>;
+
+/// Internal Index Tree
+pub type TopicTree<T> = Arc<
+    RwLock<
+        BTreeMap<
+            // Index with a subscription unique ID
+            (<T as Spec>::Topic, usize),
+            Subscriber<T>,
+        >,
+    >,
+>;
+
+/// Manager
+pub struct Pubsub<S>
+where
+    S: Spec + 'static,
+{
+    inner: Arc<S>,
+    listeners_topics: TopicTree<S>,
+    unique_subscription_counter: AtomicUsize,
+    active_subscribers: Arc<AtomicUsize>,
+}
+
+impl<S> Pubsub<S>
+where
+    S: Spec + 'static,
+{
+    /// Create a new instance
+    pub fn new(inner: Arc<S>) -> Self {
+        Self {
+            inner,
+            listeners_topics: Default::default(),
+            unique_subscription_counter: 0.into(),
+            active_subscribers: Arc::new(0.into()),
+        }
+    }
+
+    /// Total number of active subscribers, it is not the number of active topics being subscribed
+    pub fn active_subscribers(&self) -> usize {
+        self.active_subscribers
+            .load(std::sync::atomic::Ordering::Relaxed)
+    }
+
+    /// Publish an event to all listenrs
+    #[inline(always)]
+    fn publish_internal(event: S::Event, listeners_index: &TopicTree<S>) -> Result<(), Error> {
+        let index_storage = listeners_index.read();
+
+        let mut sent = HashSet::new();
+        for topic in event.get_topics() {
+            for ((subscription_index, unique_id), sender) in
+                index_storage.range((topic.clone(), 0)..)
+            {
+                if subscription_index.cmp(&topic) != Ordering::Equal {
+                    break;
+                }
+                if sent.contains(&unique_id) {
+                    continue;
+                }
+                sent.insert(unique_id);
+                sender.send(event.clone());
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Broadcast an event to all listeners
+    #[inline(always)]
+    pub fn publish<E>(&self, event: E)
+    where
+        E: Into<S::Event>,
+    {
+        let topics = self.listeners_topics.clone();
+        let event = event.into();
+
+        #[cfg(not(target_arch = "wasm32"))]
+        tokio::spawn(async move {
+            let _ = Self::publish_internal(event, &topics);
+        });
+
+        #[cfg(target_arch = "wasm32")]
+        wasm_bindgen_futures::spawn_local(async move {
+            let _ = Self::publish_internal(event, &topics);
+        });
+    }
+
+    /// Broadcast an event to all listeners right away, blocking the current thread
+    ///
+    /// This function takes an Arc to the storage struct, the event_id, the kind
+    /// and the vent to broadcast
+    #[inline(always)]
+    pub fn publish_now<E>(&self, event: E) -> Result<(), Error>
+    where
+        E: Into<S::Event>,
+    {
+        let event = event.into();
+        Self::publish_internal(event, &self.listeners_topics)
+    }
+
+    /// Subscribe proving custom sender/receiver mpsc
+    #[inline(always)]
+    pub fn subscribe_with<I>(
+        &self,
+        request: I,
+        sender: &mpsc::Sender<(Arc<I::SubscriptionId>, S::Event)>,
+        receiver: Option<SubReceiver<S>>,
+    ) -> Result<ActiveSubscription<S>, Error>
+    where
+        I: SubscriptionRequest<
+            Topic = <S::Event as Event>::Topic,
+            SubscriptionId = S::SubscriptionId,
+        >,
+    {
+        let subscription_name = request.subscription_name();
+        let sender = Subscriber::new(subscription_name.clone(), sender);
+        let mut index_storage = self.listeners_topics.write();
+        let subscription_internal_id = self
+            .unique_subscription_counter
+            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+
+        self.active_subscribers
+            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+
+        let subscribed_to = request.try_get_topics()?;
+
+        for index in subscribed_to.iter() {
+            index_storage.insert((index.clone(), subscription_internal_id), sender.clone());
+        }
+        drop(index_storage);
+
+        let inner = self.inner.clone();
+        let subscribed_to_for_spawn = subscribed_to.clone();
+
+        #[cfg(not(target_arch = "wasm32"))]
+        tokio::spawn(async move {
+            // TODO: Ignore topics broadcasted from fetch_events _if_ any real time has been broadcasted already.
+            inner.fetch_events(subscribed_to_for_spawn, sender).await;
+        });
+
+        #[cfg(target_arch = "wasm32")]
+        wasm_bindgen_futures::spawn_local(async move {
+            inner.fetch_events(subscribed_to_for_spawn, sender).await;
+        });
+
+        Ok(ActiveSubscription::new(
+            subscription_internal_id,
+            subscription_name,
+            self.active_subscribers.clone(),
+            self.listeners_topics.clone(),
+            subscribed_to,
+            receiver,
+        ))
+    }
+
+    /// Subscribe
+    pub fn subscribe<I>(&self, request: I) -> Result<ActiveSubscription<S>, Error>
+    where
+        I: SubscriptionRequest<
+            Topic = <S::Event as Event>::Topic,
+            SubscriptionId = S::SubscriptionId,
+        >,
+    {
+        let (sender, receiver) = mpsc::channel(DEFAULT_CHANNEL_SIZE);
+        self.subscribe_with(request, &sender, Some(receiver))
+    }
+}

crates/cdk-common/src/pub_sub/remote_consumer.rs

@@ -0,0 +1,885 @@
+//! Pub-sub consumer
+//!
+//! Consumers are designed to connect to a producer, through a transport, and subscribe to events.
+use std::collections::{HashMap, VecDeque};
+use std::sync::atomic::AtomicBool;
+use std::sync::Arc;
+use std::time::Duration;
+
+use parking_lot::RwLock;
+use tokio::sync::mpsc;
+use tokio::time::{sleep, Instant};
+
+use super::subscriber::{ActiveSubscription, SubscriptionRequest};
+use super::{Error, Event, Pubsub, Spec};
+
+const STREAM_CONNECTION_BACKOFF: Duration = Duration::from_millis(2_000);
+
+const STREAM_CONNECTION_MAX_BACKOFF: Duration = Duration::from_millis(30_000);
+
+const INTERNAL_POLL_SIZE: usize = 1_000;
+
+const POLL_SLEEP: Duration = Duration::from_millis(2_000);
+
+#[cfg(target_arch = "wasm32")]
+use wasm_bindgen_futures;
+
+struct UniqueSubscription<S>
+where
+    S: Spec,
+{
+    name: S::SubscriptionId,
+    total_subscribers: usize,
+}
+
+type UniqueSubscriptions<S> = RwLock<HashMap<<S as Spec>::Topic, UniqueSubscription<S>>>;
+
+type ActiveSubscriptions<S> =
+    RwLock<HashMap<Arc<<S as Spec>::SubscriptionId>, Vec<<S as Spec>::Topic>>>;
+
+type CacheEvent<S> = HashMap<<<S as Spec>::Event as Event>::Topic, <S as Spec>::Event>;
+
+/// Subscription consumer
+pub struct Consumer<T>
+where
+    T: Transport + 'static,
+{
+    transport: T,
+    inner_pubsub: Arc<Pubsub<T::Spec>>,
+    remote_subscriptions: UniqueSubscriptions<T::Spec>,
+    subscriptions: ActiveSubscriptions<T::Spec>,
+    stream_ctrl: RwLock<Option<mpsc::Sender<StreamCtrl<T::Spec>>>>,
+    still_running: AtomicBool,
+    prefer_polling: bool,
+    /// Cached events
+    ///
+    /// The cached events are useful to share events. The cache is automatically evicted it is
+    /// disconnected from the remote source, meaning the cache is only active while there is an
+    /// active subscription to the remote source, and it remembers the latest event.
+    cached_events: Arc<RwLock<CacheEvent<T::Spec>>>,
+}
+
+/// Remote consumer
+pub struct RemoteActiveConsumer<T>
+where
+    T: Transport + 'static,
+{
+    inner: ActiveSubscription<T::Spec>,
+    previous_messages: VecDeque<<T::Spec as Spec>::Event>,
+    consumer: Arc<Consumer<T>>,
+}
+
+impl<T> RemoteActiveConsumer<T>
+where
+    T: Transport + 'static,
+{
+    /// Receives the next event
+    pub async fn recv(&mut self) -> Option<<T::Spec as Spec>::Event> {
+        if let Some(event) = self.previous_messages.pop_front() {
+            Some(event)
+        } else {
+            self.inner.recv().await
+        }
+    }
+
+    /// Try receive an event or return Noen right away
+    pub fn try_recv(&mut self) -> Option<<T::Spec as Spec>::Event> {
+        if let Some(event) = self.previous_messages.pop_front() {
+            Some(event)
+        } else {
+            self.inner.try_recv()
+        }
+    }
+
+    /// Get the subscription name
+    pub fn name(&self) -> &<T::Spec as Spec>::SubscriptionId {
+        self.inner.name()
+    }
+}
+
+impl<T> Drop for RemoteActiveConsumer<T>
+where
+    T: Transport + 'static,
+{
+    fn drop(&mut self) {
+        let _ = self.consumer.unsubscribe(self.name().clone());
+    }
+}
+
+/// Struct to relay events from Poll and Streams from the external subscription to the local
+/// subscribers
+pub struct InternalRelay<S>
+where
+    S: Spec + 'static,
+{
+    inner: Arc<Pubsub<S>>,
+    cached_events: Arc<RwLock<CacheEvent<S>>>,
+}
+
+impl<S> InternalRelay<S>
+where
+    S: Spec + 'static,
+{
+    /// Relay a remote event locally
+    pub fn send<X>(&self, event: X)
+    where
+        X: Into<S::Event>,
+    {
+        let event = event.into();
+        let mut cached_events = self.cached_events.write();
+
+        for topic in event.get_topics() {
+            cached_events.insert(topic, event.clone());
+        }
+
+        self.inner.publish(event);
+    }
+}
+
+impl<T> Consumer<T>
+where
+    T: Transport + 'static,
+{
+    /// Creates a new instance
+    pub fn new(
+        transport: T,
+        prefer_polling: bool,
+        context: <T::Spec as Spec>::Context,
+    ) -> Arc<Self> {
+        let this = Arc::new(Self {
+            transport,
+            prefer_polling,
+            inner_pubsub: Arc::new(Pubsub::new(T::Spec::new_instance(context))),
+            subscriptions: Default::default(),
+            remote_subscriptions: Default::default(),
+            stream_ctrl: RwLock::new(None),
+            cached_events: Default::default(),
+            still_running: true.into(),
+        });
+
+        #[cfg(not(target_arch = "wasm32"))]
+        tokio::spawn(Self::stream(this.clone()));
+
+        #[cfg(target_arch = "wasm32")]
+        wasm_bindgen_futures::spawn_local(Self::stream(this.clone()));
+
+        this
+    }
+
+    async fn stream(instance: Arc<Self>) {
+        let mut stream_supported = true;
+        let mut poll_supported = true;
+
+        let mut backoff = STREAM_CONNECTION_BACKOFF;
+        let mut retry_at = None;
+
+        loop {
+            if (!stream_supported && !poll_supported)
+                || !instance
+                    .still_running
+                    .load(std::sync::atomic::Ordering::Relaxed)
+            {
+                break;
+            }
+
+            if instance.remote_subscriptions.read().is_empty() {
+                sleep(Duration::from_millis(100)).await;
+                continue;
+            }
+
+            if stream_supported
+                && !instance.prefer_polling
+                && retry_at
+                    .map(|retry_at| retry_at < Instant::now())
+                    .unwrap_or(true)
+            {
+                let (sender, receiver) = mpsc::channel(INTERNAL_POLL_SIZE);
+
+                {
+                    *instance.stream_ctrl.write() = Some(sender);
+                }
+
+                let current_subscriptions = {
+                    instance
+                        .remote_subscriptions
+                        .read()
+                        .iter()
+                        .map(|(key, name)| (name.name.clone(), key.clone()))
+                        .collect::<Vec<_>>()
+                };
+
+                if let Err(err) = instance
+                    .transport
+                    .stream(
+                        receiver,
+                        current_subscriptions,
+                        InternalRelay {
+                            inner: instance.inner_pubsub.clone(),
+                            cached_events: instance.cached_events.clone(),
+                        },
+                    )
+                    .await
+                {
+                    retry_at = Some(Instant::now() + backoff);
+                    backoff =
+                        (backoff + STREAM_CONNECTION_BACKOFF).min(STREAM_CONNECTION_MAX_BACKOFF);
+
+                    if matches!(err, Error::NotSupported) {
+                        stream_supported = false;
+                    }
+                    tracing::error!("Long connection failed with error {:?}", err);
+                } else {
+                    backoff = STREAM_CONNECTION_BACKOFF;
+                }
+
+                // remove sender to stream, as there is no stream
+                let _ = instance.stream_ctrl.write().take();
+            }
+
+            if poll_supported {
+                let current_subscriptions = {
+                    instance
+                        .remote_subscriptions
+                        .read()
+                        .iter()
+                        .map(|(key, name)| (name.name.clone(), key.clone()))
+                        .collect::<Vec<_>>()
+                };
+
+                if let Err(err) = instance
+                    .transport
+                    .poll(
+                        current_subscriptions,
+                        InternalRelay {
+                            inner: instance.inner_pubsub.clone(),
+                            cached_events: instance.cached_events.clone(),
+                        },
+                    )
+                    .await
+                {
+                    if matches!(err, Error::NotSupported) {
+                        poll_supported = false;
+                    }
+                    tracing::error!("Polling failed with error {:?}", err);
+                }
+
+                sleep(POLL_SLEEP).await;
+            }
+        }
+    }
+
+    /// Unsubscribe from a topic, this is called automatically when RemoteActiveSubscription<T> goes
+    /// out of scope
+    fn unsubscribe(
+        self: &Arc<Self>,
+        subscription_name: <T::Spec as Spec>::SubscriptionId,
+    ) -> Result<(), Error> {
+        let topics = self
+            .subscriptions
+            .write()
+            .remove(&subscription_name)
+            .ok_or(Error::NoSubscription)?;
+
+        let mut remote_subscriptions = self.remote_subscriptions.write();
+
+        for topic in topics {
+            let mut remote_subscription =
+                if let Some(remote_subscription) = remote_subscriptions.remove(&topic) {
+                    remote_subscription
+                } else {
+                    continue;
+                };
+
+            remote_subscription.total_subscribers = remote_subscription
+                .total_subscribers
+                .checked_sub(1)
+                .unwrap_or_default();
+
+            if remote_subscription.total_subscribers == 0 {
+                let mut cached_events = self.cached_events.write();
+
+                cached_events.remove(&topic);
+
+                self.message_to_stream(StreamCtrl::Unsubscribe(remote_subscription.name.clone()))?;
+            } else {
+                remote_subscriptions.insert(topic, remote_subscription);
+            }
+        }
+
+        if remote_subscriptions.is_empty() {
+            self.message_to_stream(StreamCtrl::Stop)?;
+        }
+
+        Ok(())
+    }
+
+    #[inline(always)]
+    fn message_to_stream(&self, message: StreamCtrl<T::Spec>) -> Result<(), Error> {
+        let to_stream = self.stream_ctrl.read();
+
+        if let Some(to_stream) = to_stream.as_ref() {
+            Ok(to_stream.try_send(message)?)
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Creates a subscription
+    ///
+    /// The subscriptions have two parts:
+    ///
+    /// 1. Will create the subscription to the remote Pubsub service, Any events will be moved to
+    ///    the internal pubsub
+    ///
+    /// 2. The internal subscription to the inner Pubsub. Because all subscriptions are going the
+    ///    transport, once events matches subscriptions, the inner_pubsub will receive the message and
+    ///    broadcasat the event.
+    pub fn subscribe<I>(self: &Arc<Self>, request: I) -> Result<RemoteActiveConsumer<T>, Error>
+    where
+        I: SubscriptionRequest<
+            Topic = <T::Spec as Spec>::Topic,
+            SubscriptionId = <T::Spec as Spec>::SubscriptionId,
+        >,
+    {
+        let subscription_name = request.subscription_name();
+        let topics = request.try_get_topics()?;
+
+        let mut remote_subscriptions = self.remote_subscriptions.write();
+        let mut subscriptions = self.subscriptions.write();
+
+        if subscriptions.get(&subscription_name).is_some() {
+            return Err(Error::NoSubscription);
+        }
+
+        let mut previous_messages = Vec::new();
+        let cached_events = self.cached_events.read();
+
+        for topic in topics.iter() {
+            if let Some(subscription) = remote_subscriptions.get_mut(topic) {
+                subscription.total_subscribers += 1;
+
+                if let Some(v) = cached_events.get(topic).cloned() {
+                    previous_messages.push(v);
+                }
+            } else {
+                let internal_sub_name = self.transport.new_name();
+                remote_subscriptions.insert(
+                    topic.clone(),
+                    UniqueSubscription {
+                        total_subscribers: 1,
+                        name: internal_sub_name.clone(),
+                    },
+                );
+
+                // new subscription is created, so the connection worker should be notified
+                self.message_to_stream(StreamCtrl::Subscribe((internal_sub_name, topic.clone())))?;
+            }
+        }
+
+        subscriptions.insert(subscription_name, topics);
+        drop(subscriptions);
+
+        Ok(RemoteActiveConsumer {
+            inner: self.inner_pubsub.subscribe(request)?,
+            previous_messages: previous_messages.into(),
+            consumer: self.clone(),
+        })
+    }
+}
+
+impl<T> Drop for Consumer<T>
+where
+    T: Transport + 'static,
+{
+    fn drop(&mut self) {
+        self.still_running
+            .store(false, std::sync::atomic::Ordering::Release);
+        if let Some(to_stream) = self.stream_ctrl.read().as_ref() {
+            let _ = to_stream.try_send(StreamCtrl::Stop).inspect_err(|err| {
+                tracing::error!("Failed to send message LongPoll::Stop due to {err:?}")
+            });
+        }
+    }
+}
+
+/// Subscribe Message
+pub type SubscribeMessage<S> = (<S as Spec>::SubscriptionId, <S as Spec>::Topic);
+
+/// Messages sent from the [`Consumer`] to the [`Transport`] background loop.
+pub enum StreamCtrl<S>
+where
+    S: Spec + 'static,
+{
+    /// Add a subscription
+    Subscribe(SubscribeMessage<S>),
+    /// Desuscribe
+    Unsubscribe(S::SubscriptionId),
+    /// Exit the loop
+    Stop,
+}
+
+impl<S> Clone for StreamCtrl<S>
+where
+    S: Spec + 'static,
+{
+    fn clone(&self) -> Self {
+        match self {
+            Self::Subscribe(s) => Self::Subscribe(s.clone()),
+            Self::Unsubscribe(u) => Self::Unsubscribe(u.clone()),
+            Self::Stop => Self::Stop,
+        }
+    }
+}
+
+/// Transport abstracts how the consumer talks to the remote pubsub.
+///
+/// Implement this on your HTTP/WebSocket client. The transport is responsible for:
+/// - creating unique subscription names,
+/// - keeping a long connection via `stream` **or** performing on-demand `poll`,
+/// - forwarding remote events to `InternalRelay`.
+///
+/// ```ignore
+/// struct WsTransport { /* ... */ }
+/// #[async_trait::async_trait]
+/// impl Transport for WsTransport {
+///     type Topic = MyTopic;
+///     fn new_name(&self) -> <Self::Topic as Topic>::SubscriptionName { 0 }
+///     async fn stream(/* ... */) -> Result<(), Error> { Ok(()) }
+///     async fn poll(/* ... */) -> Result<(), Error> { Ok(()) }
+/// }
+/// ```
+#[cfg_attr(target_arch = "wasm32", async_trait::async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait::async_trait)]
+pub trait Transport: Send + Sync {
+    /// Spec
+    type Spec: Spec;
+
+    /// Create a new subscription name
+    fn new_name(&self) -> <Self::Spec as Spec>::SubscriptionId;
+
+    /// Opens a persistent connection and continuously streams events.
+    /// For protocols that support server push (e.g. WebSocket, SSE).
+    async fn stream(
+        &self,
+        subscribe_changes: mpsc::Receiver<StreamCtrl<Self::Spec>>,
+        topics: Vec<SubscribeMessage<Self::Spec>>,
+        reply_to: InternalRelay<Self::Spec>,
+    ) -> Result<(), Error>;
+
+    /// Performs a one-shot fetch of any currently available events.
+    /// Called repeatedly by the consumer when streaming is not available.
+    async fn poll(
+        &self,
+        topics: Vec<SubscribeMessage<Self::Spec>>,
+        reply_to: InternalRelay<Self::Spec>,
+    ) -> Result<(), Error>;
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    use std::sync::Arc;
+
+    use tokio::sync::{mpsc, Mutex};
+    use tokio::time::{timeout, Duration};
+
+    use super::{
+        InternalRelay, RemoteActiveConsumer, StreamCtrl, SubscribeMessage, Transport,
+        INTERNAL_POLL_SIZE,
+    };
+    use crate::pub_sub::remote_consumer::Consumer;
+    use crate::pub_sub::test::{CustomPubSub, IndexTest, Message};
+    use crate::pub_sub::{Error, Spec, SubscriptionRequest};
+
+    // ===== Test Event/Topic types =====
+
+    #[derive(Clone, Debug)]
+    enum SubscriptionReq {
+        Foo(String, u64),
+        Bar(String, u64),
+    }
+
+    impl SubscriptionRequest for SubscriptionReq {
+        type Topic = IndexTest;
+
+        type SubscriptionId = String;
+
+        fn try_get_topics(&self) -> Result<Vec<Self::Topic>, Error> {
+            Ok(vec![match self {
+                SubscriptionReq::Foo(_, n) => IndexTest::Foo(*n),
+                SubscriptionReq::Bar(_, n) => IndexTest::Bar(*n),
+            }])
+        }
+
+        fn subscription_name(&self) -> Arc<Self::SubscriptionId> {
+            Arc::new(match self {
+                SubscriptionReq::Foo(n, _) => n.to_string(),
+                SubscriptionReq::Bar(n, _) => n.to_string(),
+            })
+        }
+    }
+
+    // ===== A controllable in-memory Transport used by tests =====
+
+    /// TestTransport relays messages from a broadcast channel to the Consumer via `InternalRelay`.
+    /// It also forwards Subscribe/Unsubscribe/Stop signals to an observer channel so tests can assert them.
+    struct TestTransport {
+        name_ctr: AtomicUsize,
+        // We forward all transport-loop control messages here so tests can observe them.
+        observe_ctrl_tx: mpsc::Sender<StreamCtrl<CustomPubSub>>,
+        // Whether stream / poll are supported.
+        support_long: bool,
+        support_poll: bool,
+        rx: Mutex<mpsc::Receiver<Message>>,
+    }
+
+    impl TestTransport {
+        fn new(
+            support_long: bool,
+            support_poll: bool,
+        ) -> (
+            Self,
+            mpsc::Sender<Message>,
+            mpsc::Receiver<StreamCtrl<CustomPubSub>>,
+        ) {
+            let (events_tx, rx) = mpsc::channel::<Message>(INTERNAL_POLL_SIZE);
+            let (observe_ctrl_tx, observe_ctrl_rx) =
+                mpsc::channel::<StreamCtrl<_>>(INTERNAL_POLL_SIZE);
+
+            let t = TestTransport {
+                name_ctr: AtomicUsize::new(1),
+                rx: Mutex::new(rx),
+                observe_ctrl_tx,
+                support_long,
+                support_poll,
+            };
+
+            (t, events_tx, observe_ctrl_rx)
+        }
+    }
+
+    #[async_trait::async_trait]
+    impl Transport for TestTransport {
+        type Spec = CustomPubSub;
+
+        fn new_name(&self) -> <Self::Spec as Spec>::SubscriptionId {
+            format!("sub-{}", self.name_ctr.fetch_add(1, Ordering::Relaxed))
+        }
+
+        async fn stream(
+            &self,
+            mut subscribe_changes: mpsc::Receiver<StreamCtrl<Self::Spec>>,
+            topics: Vec<SubscribeMessage<Self::Spec>>,
+            reply_to: InternalRelay<Self::Spec>,
+        ) -> Result<(), Error> {
+            if !self.support_long {
+                return Err(Error::NotSupported);
+            }
+
+            // Each invocation creates a fresh broadcast receiver
+            let mut rx = self.rx.lock().await;
+            let observe = self.observe_ctrl_tx.clone();
+
+            for topic in topics {
+                observe.try_send(StreamCtrl::Subscribe(topic)).unwrap();
+            }
+
+            loop {
+                tokio::select! {
+                    // Forward any control (Subscribe/Unsubscribe/Stop) messages so the test can assert them.
+                    Some(ctrl) = subscribe_changes.recv() => {
+                        observe.try_send(ctrl.clone()).unwrap();
+                        if matches!(ctrl, StreamCtrl::Stop) {
+                            break;
+                        }
+                    }
+                    // Relay external events into the inner pubsub
+                    Some(msg) = rx.recv() => {
+                        reply_to.send(msg);
+                    }
+                }
+            }
+
+            Ok(())
+        }
+
+        async fn poll(
+            &self,
+            _topics: Vec<SubscribeMessage<Self::Spec>>,
+            reply_to: InternalRelay<Self::Spec>,
+        ) -> Result<(), Error> {
+            if !self.support_poll {
+                return Err(Error::NotSupported);
+            }
+
+            // On each poll call, drain anything currently pending and return.
+            // (The Consumer calls this repeatedly; first call happens immediately.)
+            let mut rx = self.rx.lock().await;
+            // Non-blocking drain pass: try a few times without sleeping to keep tests snappy
+            for _ in 0..32 {
+                match rx.try_recv() {
+                    Ok(msg) => reply_to.send(msg),
+                    Err(mpsc::error::TryRecvError::Empty) => continue,
+                    Err(mpsc::error::TryRecvError::Disconnected) => break,
+                }
+            }
+            Ok(())
+        }
+    }
+
+    // ===== Helpers =====
+
+    async fn recv_next<T: Transport>(
+        sub: &mut RemoteActiveConsumer<T>,
+        dur_ms: u64,
+    ) -> Option<<T::Spec as Spec>::Event> {
+        timeout(Duration::from_millis(dur_ms), sub.recv())
+            .await
+            .ok()
+            .flatten()
+    }
+
+    async fn expect_ctrl(
+        rx: &mut mpsc::Receiver<StreamCtrl<CustomPubSub>>,
+        dur_ms: u64,
+        pred: impl Fn(&StreamCtrl<CustomPubSub>) -> bool,
+    ) -> StreamCtrl<CustomPubSub> {
+        timeout(Duration::from_millis(dur_ms), async {
+            loop {
+                if let Some(msg) = rx.recv().await {
+                    if pred(&msg) {
+                        break msg;
+                    }
+                }
+            }
+        })
+        .await
+        .expect("timed out waiting for control message")
+    }
+
+    // ===== Tests =====
+
+    #[tokio::test]
+    async fn stream_delivery_and_unsubscribe_on_drop() {
+        // stream supported, poll supported (doesn't matter; prefer long)
+        let (transport, events_tx, mut ctrl_rx) = TestTransport::new(true, true);
+
+        // prefer_polling = false so connection loop will try stream first.
+        let consumer = Consumer::new(transport, false, ());
+
+        // Subscribe to Foo(7)
+        let mut sub = consumer
+            .subscribe(SubscriptionReq::Foo("t".to_owned(), 7))
+            .expect("subscribe ok");
+
+        // We should see a Subscribe(name, topic) forwarded to transport
+        let ctrl = expect_ctrl(
+            &mut ctrl_rx,
+            1000,
+            |m| matches!(m, StreamCtrl::Subscribe((_, idx)) if *idx == IndexTest::Foo(7)),
+        )
+        .await;
+        match ctrl {
+            StreamCtrl::Subscribe((name, idx)) => {
+                assert_ne!(name, "t".to_owned());
+                assert_eq!(idx, IndexTest::Foo(7));
+            }
+            _ => unreachable!(),
+        }
+
+        // Send an event that matches Foo(7)
+        events_tx.send(Message { foo: 7, bar: 1 }).await.unwrap();
+        let got = recv_next::<TestTransport>(&mut sub, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 1 });
+
+        // Dropping the RemoteActiveConsumer should trigger an Unsubscribe(name)
+        drop(sub);
+        let _ctrl = expect_ctrl(&mut ctrl_rx, 1000, |m| {
+            matches!(m, StreamCtrl::Unsubscribe(_))
+        })
+        .await;
+
+        // Drop the Consumer -> Stop is sent so the transport loop exits cleanly
+        drop(consumer);
+        let _ = expect_ctrl(&mut ctrl_rx, 1000, |m| matches!(m, StreamCtrl::Stop)).await;
+    }
+
+    #[tokio::test]
+    async fn test_cache_and_invalation() {
+        // stream supported, poll supported (doesn't matter; prefer long)
+        let (transport, events_tx, mut ctrl_rx) = TestTransport::new(true, true);
+
+        // prefer_polling = false so connection loop will try stream first.
+        let consumer = Consumer::new(transport, false, ());
+
+        // Subscribe to Foo(7)
+        let mut sub_1 = consumer
+            .subscribe(SubscriptionReq::Foo("t".to_owned(), 7))
+            .expect("subscribe ok");
+
+        // We should see a Subscribe(name, topic) forwarded to transport
+        let ctrl = expect_ctrl(
+            &mut ctrl_rx,
+            1000,
+            |m| matches!(m, StreamCtrl::Subscribe((_, idx)) if *idx == IndexTest::Foo(7)),
+        )
+        .await;
+        match ctrl {
+            StreamCtrl::Subscribe((name, idx)) => {
+                assert_ne!(name, "t1".to_owned());
+                assert_eq!(idx, IndexTest::Foo(7));
+            }
+            _ => unreachable!(),
+        }
+
+        // Send an event that matches Foo(7)
+        events_tx.send(Message { foo: 7, bar: 1 }).await.unwrap();
+        let got = recv_next::<TestTransport>(&mut sub_1, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 1 });
+
+        // Subscribe to Foo(7), should receive the latest message and future messages
+        let mut sub_2 = consumer
+            .subscribe(SubscriptionReq::Foo("t2".to_owned(), 7))
+            .expect("subscribe ok");
+
+        let got = recv_next::<TestTransport>(&mut sub_2, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 1 });
+
+        // Dropping the RemoteActiveConsumer but not unsubscribe, since sub_2 is still active
+        drop(sub_1);
+
+        // Subscribe to Foo(7), should receive the latest message and future messages
+        let mut sub_3 = consumer
+            .subscribe(SubscriptionReq::Foo("t3".to_owned(), 7))
+            .expect("subscribe ok");
+
+        // receive cache message
+        let got = recv_next::<TestTransport>(&mut sub_3, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 1 });
+
+        // Send an event that matches Foo(7)
+        events_tx.send(Message { foo: 7, bar: 2 }).await.unwrap();
+
+        // receive new message
+        let got = recv_next::<TestTransport>(&mut sub_2, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 2 });
+
+        let got = recv_next::<TestTransport>(&mut sub_3, 1000)
+            .await
+            .expect("got event");
+        assert_eq!(got, Message { foo: 7, bar: 2 });
+
+        drop(sub_2);
+        drop(sub_3);
+
+        let _ctrl = expect_ctrl(&mut ctrl_rx, 1000, |m| {
+            matches!(m, StreamCtrl::Unsubscribe(_))
+        })
+        .await;
+
+        // The cache should be dropped, so no new messages
+        let mut sub_4 = consumer
+            .subscribe(SubscriptionReq::Foo("t4".to_owned(), 7))
+            .expect("subscribe ok");
+
+        assert!(
+            recv_next::<TestTransport>(&mut sub_4, 1000).await.is_none(),
+            "Should have not receive any update"
+        );
+
+        drop(sub_4);
+
+        // Drop the Consumer -> Stop is sent so the transport loop exits cleanly
+        let _ = expect_ctrl(&mut ctrl_rx, 2000, |m| matches!(m, StreamCtrl::Stop)).await;
+    }
+
+    #[tokio::test]
+    async fn falls_back_to_poll_when_stream_not_supported() {
+        // stream NOT supported, poll supported
+        let (transport, events_tx, _) = TestTransport::new(false, true);
+        // prefer_polling = true nudges the connection loop to poll first, but even if it
+        // tried stream, our transport returns NotSupported and the loop will use poll.
+        let consumer = Consumer::new(transport, true, ());
+
+        // Subscribe to Bar(5)
+        let mut sub = consumer
+            .subscribe(SubscriptionReq::Bar("t".to_owned(), 5))
+            .expect("subscribe ok");
+
+        // Inject an event; the poll path should relay it on the first poll iteration
+        events_tx.send(Message { foo: 9, bar: 5 }).await.unwrap();
+        let got = recv_next::<TestTransport>(&mut sub, 1500)
+            .await
+            .expect("event relayed via polling");
+        assert_eq!(got, Message { foo: 9, bar: 5 });
+    }
+
+    #[tokio::test]
+    async fn multiple_subscribers_share_single_remote_subscription() {
+        // This validates the "coalescing" behavior in Consumer::subscribe where multiple local
+        // subscribers to the same Topic should only create one remote subscription.
+        let (transport, events_tx, mut ctrl_rx) = TestTransport::new(true, true);
+        let consumer = Consumer::new(transport, false, ());
+
+        // Two local subscriptions to the SAME topic/name pair (different names)
+        let mut a = consumer
+            .subscribe(SubscriptionReq::Foo("t".to_owned(), 1))
+            .expect("subscribe A");
+        let _ = expect_ctrl(
+            &mut ctrl_rx,
+            1000,
+            |m| matches!(m, StreamCtrl::Subscribe((_, idx)) if  *idx == IndexTest::Foo(1)),
+        )
+        .await;
+
+        let mut b = consumer
+            .subscribe(SubscriptionReq::Foo("b".to_owned(), 1))
+            .expect("subscribe B");
+
+        // No second Subscribe should be forwarded for the same topic (coalesced).
+        // Give a little time; if one appears, we'll fail explicitly.
+        if let Ok(Some(StreamCtrl::Subscribe((_, idx)))) =
+            timeout(Duration::from_millis(400), ctrl_rx.recv()).await
+        {
+            assert_ne!(idx, IndexTest::Foo(1), "should not resubscribe same topic");
+        }
+
+        // Send one event and ensure BOTH local subscribers receive it.
+        events_tx.send(Message { foo: 1, bar: 42 }).await.unwrap();
+        let got_a = recv_next::<TestTransport>(&mut a, 1000)
+            .await
+            .expect("A got");
+        let got_b = recv_next::<TestTransport>(&mut b, 1000)
+            .await
+            .expect("B got");
+        assert_eq!(got_a, Message { foo: 1, bar: 42 });
+        assert_eq!(got_b, Message { foo: 1, bar: 42 });
+
+        // Drop B: no Unsubscribe should be sent yet (still one local subscriber).
+        drop(b);
+        if let Ok(Some(StreamCtrl::Unsubscribe(_))) =
+            timeout(Duration::from_millis(400), ctrl_rx.recv()).await
+        {
+            panic!("Should NOT unsubscribe while another local subscriber exists");
+        }
+
+        // Drop A: now remote unsubscribe should occur.
+        drop(a);
+        let _ = expect_ctrl(&mut ctrl_rx, 1000, |m| {
+            matches!(m, StreamCtrl::Unsubscribe(_))
+        })
+        .await;
+
+        let _ = expect_ctrl(&mut ctrl_rx, 1000, |m| matches!(m, StreamCtrl::Stop)).await;
+    }
+}

crates/cdk-common/src/pub_sub/subscriber.rs

@@ -0,0 +1,159 @@
+//! Active subscription
+use std::fmt::Debug;
+use std::sync::atomic::AtomicUsize;
+use std::sync::{Arc, Mutex};
+
+use tokio::sync::mpsc;
+
+use super::pubsub::{SubReceiver, TopicTree};
+use super::{Error, Spec};
+
+/// Subscription request
+pub trait SubscriptionRequest {
+    /// Topics
+    type Topic;
+
+    /// Subscription Id
+    type SubscriptionId;
+
+    /// Try to get topics from the request
+    fn try_get_topics(&self) -> Result<Vec<Self::Topic>, Error>;
+
+    /// Get the subscription name
+    fn subscription_name(&self) -> Arc<Self::SubscriptionId>;
+}
+
+/// Active Subscription
+pub struct ActiveSubscription<S>
+where
+    S: Spec + 'static,
+{
+    id: usize,
+    name: Arc<S::SubscriptionId>,
+    active_subscribers: Arc<AtomicUsize>,
+    topics: TopicTree<S>,
+    subscribed_to: Vec<S::Topic>,
+    receiver: Option<SubReceiver<S>>,
+}
+
+impl<S> ActiveSubscription<S>
+where
+    S: Spec + 'static,
+{
+    /// Creates a new instance
+    pub fn new(
+        id: usize,
+        name: Arc<S::SubscriptionId>,
+        active_subscribers: Arc<AtomicUsize>,
+        topics: TopicTree<S>,
+        subscribed_to: Vec<S::Topic>,
+        receiver: Option<SubReceiver<S>>,
+    ) -> Self {
+        Self {
+            id,
+            name,
+            active_subscribers,
+            subscribed_to,
+            topics,
+            receiver,
+        }
+    }
+
+    /// Receives the next event
+    pub async fn recv(&mut self) -> Option<S::Event> {
+        self.receiver.as_mut()?.recv().await.map(|(_, event)| event)
+    }
+
+    /// Try receive an event or return Noen right away
+    pub fn try_recv(&mut self) -> Option<S::Event> {
+        self.receiver
+            .as_mut()?
+            .try_recv()
+            .ok()
+            .map(|(_, event)| event)
+    }
+
+    /// Get the subscription name
+    pub fn name(&self) -> &S::SubscriptionId {
+        &self.name
+    }
+}
+
+impl<S> Drop for ActiveSubscription<S>
+where
+    S: Spec + 'static,
+{
+    fn drop(&mut self) {
+        // remove the listener
+        let mut topics = self.topics.write();
+        for index in self.subscribed_to.drain(..) {
+            topics.remove(&(index, self.id));
+        }
+
+        // decrement the number of active subscribers
+        self.active_subscribers
+            .fetch_sub(1, std::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+/// Lightweight sink used by producers to send events to subscribers.
+///
+/// You usually do not construct a `Subscriber` directly — it is provided to you in
+/// the [`Spec::fetch_events`] callback so you can backfill a new subscription.
+#[derive(Debug)]
+pub struct Subscriber<S>
+where
+    S: Spec + 'static,
+{
+    subscription: Arc<S::SubscriptionId>,
+    inner: mpsc::Sender<(Arc<S::SubscriptionId>, S::Event)>,
+    latest: Arc<Mutex<Option<S::Event>>>,
+}
+
+impl<S> Clone for Subscriber<S>
+where
+    S: Spec + 'static,
+{
+    fn clone(&self) -> Self {
+        Self {
+            subscription: self.subscription.clone(),
+            inner: self.inner.clone(),
+            latest: self.latest.clone(),
+        }
+    }
+}
+
+impl<S> Subscriber<S>
+where
+    S: Spec + 'static,
+{
+    /// Create a new instance
+    pub fn new(
+        subscription: Arc<S::SubscriptionId>,
+        inner: &mpsc::Sender<(Arc<S::SubscriptionId>, S::Event)>,
+    ) -> Self {
+        Self {
+            inner: inner.clone(),
+            subscription,
+            latest: Arc::new(Mutex::new(None)),
+        }
+    }
+
+    /// Send a message
+    pub fn send(&self, event: S::Event) {
+        let mut latest = if let Ok(reader) = self.latest.lock() {
+            reader
+        } else {
+            let _ = self.inner.try_send((self.subscription.to_owned(), event));
+            return;
+        };
+
+        if let Some(last_event) = latest.replace(event.clone()) {
+            if last_event == event {
+                return;
+            }
+        }
+
+        let _ = self.inner.try_send((self.subscription.to_owned(), event));
+    }
+}

crates/cdk-common/src/pub_sub/types.rs

@@ -0,0 +1,80 @@
+//! Pubsub Event definition
+//!
+//! The Pubsub Event defines the Topic struct and how an event can be converted to Topics.
+
+use std::hash::Hash;
+use std::sync::Arc;
+
+use serde::de::DeserializeOwned;
+use serde::Serialize;
+
+use super::Subscriber;
+
+/// Pubsub settings
+#[async_trait::async_trait]
+pub trait Spec: Send + Sync {
+    /// Topic
+    type Topic: Send
+        + Sync
+        + Clone
+        + Eq
+        + PartialEq
+        + Ord
+        + PartialOrd
+        + Hash
+        + Send
+        + Sync
+        + DeserializeOwned
+        + Serialize;
+
+    /// Event
+    type Event: Event<Topic = Self::Topic>
+        + Send
+        + Sync
+        + Eq
+        + PartialEq
+        + DeserializeOwned
+        + Serialize;
+
+    /// Subscription Id
+    type SubscriptionId: Clone
+        + Default
+        + Eq
+        + PartialEq
+        + Ord
+        + PartialOrd
+        + Hash
+        + Send
+        + Sync
+        + DeserializeOwned
+        + Serialize;
+
+    /// Create a new context
+    type Context;
+
+    /// Create a new instance from a given context
+    fn new_instance(context: Self::Context) -> Arc<Self>
+    where
+        Self: Sized;
+
+    /// Callback function that is called on new subscriptions, to back-fill optionally the previous
+    /// events
+    async fn fetch_events(
+        self: &Arc<Self>,
+        topics: Vec<<Self::Event as Event>::Topic>,
+        reply_to: Subscriber<Self>,
+    ) where
+        Self: Sized;
+}
+
+/// Event trait
+pub trait Event: Clone + Send + Sync + Eq + PartialEq + DeserializeOwned + Serialize {
+    /// Generic Topic
+    ///
+    /// It should be serializable/deserializable to be stored in the database layer and it should
+    /// also be sorted in a BTree for in-memory matching
+    type Topic;
+
+    /// To topics
+    fn get_topics(&self) -> Vec<Self::Topic>;
+}

crates/cdk-common/src/subscription.rs

@@ -1,98 +1,115 @@
 //! Subscription types and traits
-#[cfg(feature = "mint")]
+use std::ops::Deref;
 use std::str::FromStr;
+use std::sync::Arc;
 
-use cashu::nut17::{self};
+use cashu::nut17::{self, Kind, NotificationId};
-#[cfg(feature = "mint")]
-use cashu::nut17::{Error, Kind, Notification};
-#[cfg(feature = "mint")]
 use cashu::quote_id::QuoteId;
-#[cfg(feature = "mint")]
+use cashu::PublicKey;
-use cashu::{NotificationPayload, PublicKey};
-#[cfg(feature = "mint")]
 use serde::{Deserialize, Serialize};
 
-#[cfg(feature = "mint")]
+use crate::pub_sub::{Error, SubscriptionRequest};
-use crate::pub_sub::index::{Index, Indexable, SubscriptionGlobalId};
-use crate::pub_sub::SubId;
 
-/// Subscription parameters.
+/// CDK/Mint Subscription parameters.
 ///
 /// This is a concrete type alias for `nut17::Params<SubId>`.
-pub type Params = nut17::Params<SubId>;
+pub type Params = nut17::Params<Arc<SubId>>;
 
-/// Wrapper around `nut17::Params` to implement `Indexable` for `Notification`.
+impl SubscriptionRequest for Params {
-#[cfg(feature = "mint")]
+    type Topic = NotificationId<QuoteId>;
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct IndexableParams(Params);
 
-#[cfg(feature = "mint")]
+    type SubscriptionId = SubId;
-impl From<Params> for IndexableParams {
+
-    fn from(params: Params) -> Self {
+    fn subscription_name(&self) -> Arc<Self::SubscriptionId> {
-        Self(params)
+        self.id.clone()
-    }
     }
 
-#[cfg(feature = "mint")]
+    fn try_get_topics(&self) -> Result<Vec<Self::Topic>, Error> {
-impl TryFrom<IndexableParams> for Vec<Index<Notification>> {
+        self.filters
-    type Error = Error;
+            .iter()
-    fn try_from(params: IndexableParams) -> Result<Self, Self::Error> {
+            .map(|filter| match self.kind {
-        let sub_id: SubscriptionGlobalId = Default::default();
+                Kind::Bolt11MeltQuote => QuoteId::from_str(filter)
-        let params = params.0;
+                    .map(NotificationId::MeltQuoteBolt11)
-        params
+                    .map_err(|_| Error::ParsingError(filter.to_owned())),
-            .filters
+                Kind::Bolt11MintQuote => QuoteId::from_str(filter)
-            .into_iter()
+                    .map(NotificationId::MintQuoteBolt11)
-            .map(|filter| {
+                    .map_err(|_| Error::ParsingError(filter.to_owned())),
-                let idx = match params.kind {
+                Kind::ProofState => PublicKey::from_str(filter)
-                    Kind::Bolt11MeltQuote => {
+                    .map(NotificationId::ProofState)
-                        Notification::MeltQuoteBolt11(QuoteId::from_str(&filter)?)
+                    .map_err(|_| Error::ParsingError(filter.to_owned())),
-                    }
-                    Kind::Bolt11MintQuote => {
-                        Notification::MintQuoteBolt11(QuoteId::from_str(&filter)?)
-                    }
-                    Kind::ProofState => Notification::ProofState(PublicKey::from_str(&filter)?),
-                    Kind::Bolt12MintQuote => {
-                        Notification::MintQuoteBolt12(QuoteId::from_str(&filter)?)
-                    }
-                };
 
-                Ok(Index::from((idx, params.id.clone(), sub_id)))
+                Kind::Bolt12MintQuote => QuoteId::from_str(filter)
+                    .map(NotificationId::MintQuoteBolt12)
+                    .map_err(|_| Error::ParsingError(filter.to_owned())),
             })
-            .collect::<Result<_, _>>()
+            .collect::<Result<Vec<_>, _>>()
     }
 }
 
-#[cfg(feature = "mint")]
+/// Subscriptions parameters for the wallet
-impl AsRef<SubId> for IndexableParams {
+///
-    fn as_ref(&self) -> &SubId {
+/// This is because the Wallet can subscribe to non CDK quotes, where IDs are not constraint to
-        &self.0.id
+/// QuoteId
+pub type WalletParams = nut17::Params<Arc<String>>;
+
+impl SubscriptionRequest for WalletParams {
+    type Topic = NotificationId<String>;
+
+    type SubscriptionId = String;
+
+    fn subscription_name(&self) -> Arc<Self::SubscriptionId> {
+        self.id.clone()
+    }
+
+    fn try_get_topics(&self) -> Result<Vec<Self::Topic>, Error> {
+        self.filters
+            .iter()
+            .map(|filter| {
+                Ok(match self.kind {
+                    Kind::Bolt11MeltQuote => NotificationId::MeltQuoteBolt11(filter.to_owned()),
+                    Kind::Bolt11MintQuote => NotificationId::MintQuoteBolt11(filter.to_owned()),
+                    Kind::ProofState => PublicKey::from_str(filter)
+                        .map(NotificationId::ProofState)
+                        .map_err(|_| Error::ParsingError(filter.to_owned()))?,
+
+                    Kind::Bolt12MintQuote => NotificationId::MintQuoteBolt12(filter.to_owned()),
+                })
+            })
+            .collect::<Result<Vec<_>, _>>()
     }
 }
 
-#[cfg(feature = "mint")]
+/// Subscription Id wrapper
-impl Indexable for NotificationPayload<QuoteId> {
+///
-    type Type = Notification;
+/// This is the place to add some sane default (like a max length) to the
+/// subscription ID
+#[derive(Debug, Clone, Default, Eq, PartialEq, Ord, PartialOrd, Hash, Serialize, Deserialize)]
+pub struct SubId(String);
 
-    fn to_indexes(&self) -> Vec<Index<Self::Type>> {
+impl From<&str> for SubId {
-        match self {
+    fn from(s: &str) -> Self {
-            NotificationPayload::ProofState(proof_state) => {
+        Self(s.to_string())
-                vec![Index::from(Notification::ProofState(proof_state.y))]
-            }
-            NotificationPayload::MeltQuoteBolt11Response(melt_quote) => {
-                vec![Index::from(Notification::MeltQuoteBolt11(
-                    melt_quote.quote.clone(),
-                ))]
-            }
-            NotificationPayload::MintQuoteBolt11Response(mint_quote) => {
-                vec![Index::from(Notification::MintQuoteBolt11(
-                    mint_quote.quote.clone(),
-                ))]
-            }
-            NotificationPayload::MintQuoteBolt12Response(mint_quote) => {
-                vec![Index::from(Notification::MintQuoteBolt12(
-                    mint_quote.quote.clone(),
-                ))]
     }
 }
+
+impl From<String> for SubId {
+    fn from(s: String) -> Self {
+        Self(s)
+    }
+}
+
+impl FromStr for SubId {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(Self(s.to_string()))
+    }
+}
+
+impl Deref for SubId {
+    type Target = String;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
     }
 }

crates/cdk-common/src/ws.rs

@@ -2,6 +2,8 @@
 //!
 //! This module extends the `cashu` crate with types and functions for the CDK, using the correct
 //! expected ID types.
+use std::sync::Arc;
+
 #[cfg(feature = "mint")]
 use cashu::nut17::ws::JSON_RPC_VERSION;
 use cashu::nut17::{self};
@@ -10,7 +12,7 @@ use cashu::quote_id::QuoteId;
 #[cfg(feature = "mint")]
 use cashu::NotificationPayload;
 
-use crate::pub_sub::SubId;
+type SubId = Arc<crate::subscription::SubId>;
 
 /// Request to unsubscribe from a websocket subscription
 pub type WsUnsubscribeRequest = nut17::ws::WsUnsubscribeRequest<SubId>;

crates/cdk-ffi/Cargo.toml

@@ -22,7 +22,7 @@ ctor = "0.2"
 futures = { workspace = true }
 once_cell = { workspace = true }
 rand = { workspace = true }
-serde = { workspace = true, features = ["derive"] }
+serde = { workspace = true, features = ["derive", "rc"] }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true, features = ["sync", "rt", "rt-multi-thread"] }
@@ -41,4 +41,3 @@ postgres = ["cdk-postgres"]
 [[bin]]
 name = "uniffi-bindgen"
 path = "src/bin/uniffi-bindgen.rs"
-

crates/cdk-ffi/src/types/subscription.rs

@@ -1,6 +1,7 @@
 //! Subscription-related FFI types
+use std::sync::Arc;
 
-use cdk::pub_sub::SubId;
+use cdk::event::MintEvent;
 use serde::{Deserialize, Serialize};
 
 use super::proof::ProofStateUpdate;
@@ -53,21 +54,17 @@ pub struct SubscribeParams {
     pub id: Option<String>,
 }
 
-impl From<SubscribeParams> for cdk::nuts::nut17::Params<cdk::pub_sub::SubId> {
+impl From<SubscribeParams> for cdk::nuts::nut17::Params<Arc<String>> {
     fn from(params: SubscribeParams) -> Self {
-        let sub_id = params
+        let sub_id = params.id.unwrap_or_else(|| {
-            .id
-            .map(|id| SubId::from(id.as_str()))
-            .unwrap_or_else(|| {
             // Generate a random ID
-                let uuid = uuid::Uuid::new_v4();
+            uuid::Uuid::new_v4().to_string()
-                SubId::from(uuid.to_string().as_str())
         });
 
         cdk::nuts::nut17::Params {
             kind: params.kind.into(),
             filters: params.filters,
-            id: sub_id,
+            id: Arc::new(sub_id),
         }
     }
 }
@@ -132,12 +129,7 @@ impl ActiveSubscription {
     /// Try to receive a notification without blocking
     pub async fn try_recv(&self) -> Result<Option<NotificationPayload>, FfiError> {
         let mut guard = self.inner.lock().await;
-        guard
+        Ok(guard.try_recv().map(Into::into))
-            .try_recv()
-            .map(|opt| opt.map(Into::into))
-            .map_err(|e| FfiError::Generic {
-                msg: format!("Failed to receive notification: {}", e),
-            })
     }
 }
 
@@ -156,9 +148,9 @@ pub enum NotificationPayload {
     },
 }
 
-impl From<cdk::nuts::NotificationPayload<String>> for NotificationPayload {
+impl From<MintEvent<String>> for NotificationPayload {
-    fn from(payload: cdk::nuts::NotificationPayload<String>) -> Self {
+    fn from(payload: MintEvent<String>) -> Self {
-        match payload {
+        match payload.into() {
             cdk::nuts::NotificationPayload::ProofState(states) => NotificationPayload::ProofState {
                 proof_states: vec![states.into()],
             },

crates/cdk-ffi/src/wallet.rs

@@ -349,7 +349,7 @@ impl Wallet {
         &self,
         params: SubscribeParams,
     ) -> Result<std::sync::Arc<ActiveSubscription>, FfiError> {
-        let cdk_params: cdk::nuts::nut17::Params<cdk::pub_sub::SubId> = params.clone().into();
+        let cdk_params: cdk::nuts::nut17::Params<Arc<String>> = params.clone().into();
         let sub_id = cdk_params.id.to_string();
         let active_sub = self.inner.subscribe(cdk_params).await;
         Ok(std::sync::Arc::new(ActiveSubscription::new(

crates/cdk-integration-tests/tests/integration_tests_pure.rs

@@ -13,6 +13,7 @@ use std::assert_eq;
 use std::collections::{HashMap, HashSet};
 use std::hash::RandomState;
 use std::str::FromStr;
+use std::sync::Arc;
 use std::time::Duration;
 
 use cashu::amount::SplitTarget;
@@ -24,7 +25,7 @@ use cashu::{
 };
 use cdk::mint::Mint;
 use cdk::nuts::nut00::ProofsMethods;
-use cdk::subscription::{IndexableParams, Params};
+use cdk::subscription::Params;
 use cdk::wallet::types::{TransactionDirection, TransactionId};
 use cdk::wallet::{ReceiveOptions, SendMemo, SendOptions};
 use cdk::Amount;
@@ -485,15 +486,11 @@ pub async fn test_p2pk_swap() {
 
     let mut listener = mint_bob
         .pubsub_manager()
-        .try_subscribe::<IndexableParams>(
+        .subscribe(Params {
-            Params {
             kind: cdk::nuts::nut17::Kind::ProofState,
             filters: public_keys_to_listen.clone(),
-                id: "test".into(),
+            id: Arc::new("test".into()),
-            }
+        })
-            .into(),
-        )
-        .await
         .expect("valid subscription");
 
     match mint_bob.process_swap_request(swap_request).await {
@@ -520,9 +517,8 @@ pub async fn test_p2pk_swap() {
     sleep(Duration::from_secs(1)).await;
 
     let mut msgs = HashMap::new();
-    while let Ok((sub_id, msg)) = listener.try_recv() {
+    while let Some(msg) = listener.try_recv() {
-        assert_eq!(sub_id, "test".into());
+        match msg.into_inner() {
-        match msg {
             NotificationPayload::ProofState(ProofState { y, state, .. }) => {
                 msgs.entry(y.to_string())
                     .or_insert_with(Vec::new)
@@ -544,7 +540,7 @@ pub async fn test_p2pk_swap() {
         );
     }
 
-    assert!(listener.try_recv().is_err(), "no other event is happening");
+    assert!(listener.try_recv().is_none(), "no other event is happening");
     assert!(msgs.is_empty(), "Only expected key events are received");
 }
 

crates/cdk-integration-tests/tests/regtest.rs

@@ -165,7 +165,7 @@ async fn test_websocket_connection() {
         .expect("timeout waiting for unpaid notification")
         .expect("No paid notification received");
 
-    match msg {
+    match msg.into_inner() {
         NotificationPayload::MintQuoteBolt11Response(response) => {
             assert_eq!(response.quote.to_string(), mint_quote.id);
             assert_eq!(response.state, MintQuoteState::Unpaid);
@@ -185,7 +185,7 @@ async fn test_websocket_connection() {
         .expect("timeout waiting for paid notification")
         .expect("No paid notification received");
 
-    match msg {
+    match msg.into_inner() {
         NotificationPayload::MintQuoteBolt11Response(response) => {
             assert_eq!(response.quote.to_string(), mint_quote.id);
             assert_eq!(response.state, MintQuoteState::Paid);

crates/cdk/Cargo.toml

@@ -100,8 +100,6 @@ ring = { version = "0.17.14", features = ["wasm32_unknown_unknown_js"] }
 rustls = { workspace = true, optional = true }
 
 uuid = { workspace = true, features = ["js"] }
-wasm-bindgen = "0.2"
-wasm-bindgen-futures = "0.4"
 gloo-timers = { version = "0.3", features = ["futures"] }
 
 [[example]]

crates/cdk/src/event.rs

@@ -0,0 +1,127 @@
+//! Mint event types
+use std::fmt::Debug;
+use std::hash::Hash;
+use std::ops::Deref;
+
+use cdk_common::nut17::NotificationId;
+use cdk_common::pub_sub::Event;
+use cdk_common::{
+    MeltQuoteBolt11Response, MintQuoteBolt11Response, MintQuoteBolt12Response, NotificationPayload,
+    ProofState,
+};
+use serde::de::DeserializeOwned;
+use serde::{Deserialize, Serialize};
+
+/// Simple wrapper over `NotificationPayload<QuoteId>` which is a foreign type
+#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
+#[serde(bound = "T: Serialize + DeserializeOwned")]
+pub struct MintEvent<T>(NotificationPayload<T>)
+where
+    T: Clone + Eq + PartialEq;
+
+impl<T> From<MintEvent<T>> for NotificationPayload<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: MintEvent<T>) -> Self {
+        value.0
+    }
+}
+
+impl<T> Deref for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    type Target = NotificationPayload<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T> From<ProofState> for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: ProofState) -> Self {
+        Self(NotificationPayload::ProofState(value))
+    }
+}
+
+impl<T> MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    /// New instance
+    pub fn new(t: NotificationPayload<T>) -> Self {
+        Self(t)
+    }
+
+    /// Get inner
+    pub fn inner(&self) -> &NotificationPayload<T> {
+        &self.0
+    }
+
+    /// Into inner
+    pub fn into_inner(self) -> NotificationPayload<T> {
+        self.0
+    }
+}
+
+impl<T> From<NotificationPayload<T>> for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: NotificationPayload<T>) -> Self {
+        Self(value)
+    }
+}
+
+impl<T> From<MintQuoteBolt11Response<T>> for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: MintQuoteBolt11Response<T>) -> Self {
+        Self(NotificationPayload::MintQuoteBolt11Response(value))
+    }
+}
+
+impl<T> From<MeltQuoteBolt11Response<T>> for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: MeltQuoteBolt11Response<T>) -> Self {
+        Self(NotificationPayload::MeltQuoteBolt11Response(value))
+    }
+}
+
+impl<T> From<MintQuoteBolt12Response<T>> for MintEvent<T>
+where
+    T: Clone + Eq + PartialEq,
+{
+    fn from(value: MintQuoteBolt12Response<T>) -> Self {
+        Self(NotificationPayload::MintQuoteBolt12Response(value))
+    }
+}
+
+impl<T> Event for MintEvent<T>
+where
+    T: Clone + Serialize + DeserializeOwned + Debug + Ord + Hash + Send + Sync + Eq + PartialEq,
+{
+    type Topic = NotificationId<T>;
+
+    fn get_topics(&self) -> Vec<Self::Topic> {
+        vec![match &self.0 {
+            NotificationPayload::MeltQuoteBolt11Response(r) => {
+                NotificationId::MeltQuoteBolt11(r.quote.to_owned())
+            }
+            NotificationPayload::MintQuoteBolt11Response(r) => {
+                NotificationId::MintQuoteBolt11(r.quote.to_owned())
+            }
+            NotificationPayload::MintQuoteBolt12Response(r) => {
+                NotificationId::MintQuoteBolt12(r.quote.to_owned())
+            }
+            NotificationPayload::ProofState(p) => NotificationId::ProofState(p.y.to_owned()),
+        }]
+    }
+}

crates/cdk/src/lib.rs

@@ -32,11 +32,9 @@ mod bip353;
 #[cfg(all(any(feature = "wallet", feature = "mint"), feature = "auth"))]
 mod oidc_client;
 
-#[cfg(all(any(feature = "wallet", feature = "mint"), feature = "auth"))]
+#[cfg(feature = "mint")]
-pub use oidc_client::OidcClient;
+#[doc(hidden)]
-
+pub use cdk_common::payment as cdk_payment;
-pub mod pub_sub;
-
 /// Re-export amount type
 #[doc(hidden)]
 pub use cdk_common::{
@@ -44,10 +42,11 @@ pub use cdk_common::{
     error::{self, Error},
     lightning_invoice, mint_url, nuts, secret, util, ws, Amount, Bolt11Invoice,
 };
-#[cfg(feature = "mint")]
+#[cfg(all(any(feature = "wallet", feature = "mint"), feature = "auth"))]
-#[doc(hidden)]
+pub use oidc_client::OidcClient;
-pub use cdk_common::{payment as cdk_payment, subscription};
 
+#[cfg(any(feature = "wallet", feature = "mint"))]
+pub mod event;
 pub mod fees;
 
 #[doc(hidden)]
@@ -69,6 +68,8 @@ pub use self::wallet::HttpClient;
 #[doc(hidden)]
 pub type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
 
+/// Re-export subscription
+pub use cdk_common::subscription;
 /// Re-export futures::Stream
 #[cfg(any(feature = "wallet", feature = "mint"))]
 pub use futures::{Stream, StreamExt};

crates/cdk/src/mint/issue/mod.rs

@@ -322,12 +322,12 @@ impl Mint {
                 PaymentMethod::Bolt11 => {
                     let res: MintQuoteBolt11Response<QuoteId> = quote.clone().into();
                     self.pubsub_manager
-                        .broadcast(NotificationPayload::MintQuoteBolt11Response(res));
+                        .publish(NotificationPayload::MintQuoteBolt11Response(res));
                 }
                 PaymentMethod::Bolt12 => {
                     let res: MintQuoteBolt12Response<QuoteId> = quote.clone().try_into()?;
                     self.pubsub_manager
-                        .broadcast(NotificationPayload::MintQuoteBolt12Response(res));
+                        .publish(NotificationPayload::MintQuoteBolt12Response(res));
                 }
                 PaymentMethod::Custom(_) => {}
             }

crates/cdk/src/mint/mod.rs

@@ -43,7 +43,7 @@ mod ln;
 mod melt;
 mod proof_writer;
 mod start_up_check;
-pub mod subscription;
+mod subscription;
 mod swap;
 mod verification;
 
@@ -206,7 +206,7 @@ impl Mint {
 
         Ok(Self {
             signatory,
-            pubsub_manager: Arc::new(localstore.clone().into()),
+            pubsub_manager: PubSubManager::new(localstore.clone()),
             localstore,
             #[cfg(feature = "auth")]
             oidc_client: computed_info.nuts.nut21.as_ref().map(|nut21| {

crates/cdk/src/mint/subscription.rs

@@ -0,0 +1,244 @@
+//! Specific Subscription for the cdk crate
+
+use std::ops::Deref;
+use std::sync::Arc;
+
+use cdk_common::database::DynMintDatabase;
+use cdk_common::mint::MintQuote;
+use cdk_common::nut17::NotificationId;
+use cdk_common::pub_sub::{Pubsub, Spec, Subscriber};
+use cdk_common::subscription::SubId;
+use cdk_common::{
+    Amount, BlindSignature, MeltQuoteBolt11Response, MeltQuoteState, MintQuoteBolt11Response,
+    MintQuoteBolt12Response, MintQuoteState, PaymentMethod, ProofState, PublicKey, QuoteId,
+};
+
+use crate::event::MintEvent;
+
+/// Mint subtopics
+#[derive(Clone)]
+pub struct MintPubSubSpec {
+    db: DynMintDatabase,
+}
+
+impl MintPubSubSpec {
+    async fn get_events_from_db(
+        &self,
+        request: &[NotificationId<QuoteId>],
+    ) -> Result<Vec<MintEvent<QuoteId>>, String> {
+        let mut to_return = vec![];
+        let mut public_keys: Vec<PublicKey> = Vec::new();
+        let mut melt_queries = Vec::new();
+        let mut mint_queries = Vec::new();
+
+        for idx in request.iter() {
+            match idx {
+                NotificationId::ProofState(pk) => public_keys.push(*pk),
+                NotificationId::MeltQuoteBolt11(uuid) => {
+                    melt_queries.push(self.db.get_melt_quote(uuid))
+                }
+                NotificationId::MintQuoteBolt11(uuid) => {
+                    mint_queries.push(self.db.get_mint_quote(uuid))
+                }
+                NotificationId::MintQuoteBolt12(uuid) => {
+                    mint_queries.push(self.db.get_mint_quote(uuid))
+                }
+                NotificationId::MeltQuoteBolt12(uuid) => {
+                    melt_queries.push(self.db.get_melt_quote(uuid))
+                }
+            }
+        }
+
+        if !melt_queries.is_empty() {
+            to_return.extend(
+                futures::future::try_join_all(melt_queries)
+                    .await
+                    .map(|quotes| {
+                        quotes
+                            .into_iter()
+                            .filter_map(|quote| quote.map(|x| x.into()))
+                            .map(|x: MeltQuoteBolt11Response<QuoteId>| x.into())
+                            .collect::<Vec<_>>()
+                    })
+                    .map_err(|e| e.to_string())?,
+            );
+        }
+
+        if !mint_queries.is_empty() {
+            to_return.extend(
+                futures::future::try_join_all(mint_queries)
+                    .await
+                    .map(|quotes| {
+                        quotes
+                            .into_iter()
+                            .filter_map(|quote| {
+                                quote.and_then(|x| match x.payment_method {
+                                    PaymentMethod::Bolt11 => {
+                                        let response: MintQuoteBolt11Response<QuoteId> = x.into();
+                                        Some(response.into())
+                                    }
+                                    PaymentMethod::Bolt12 => match x.try_into() {
+                                        Ok(response) => {
+                                            let response: MintQuoteBolt12Response<QuoteId> =
+                                                response;
+                                            Some(response.into())
+                                        }
+                                        Err(_) => None,
+                                    },
+                                    PaymentMethod::Custom(_) => None,
+                                })
+                            })
+                            .collect::<Vec<_>>()
+                    })
+                    .map_err(|e| e.to_string())?,
+            );
+        }
+
+        if !public_keys.is_empty() {
+            to_return.extend(
+                self.db
+                    .get_proofs_states(public_keys.as_slice())
+                    .await
+                    .map_err(|e| e.to_string())?
+                    .into_iter()
+                    .enumerate()
+                    .filter_map(|(idx, state)| state.map(|state| (public_keys[idx], state).into()))
+                    .map(|state: ProofState| state.into()),
+            );
+        }
+
+        Ok(to_return)
+    }
+}
+
+#[async_trait::async_trait]
+impl Spec for MintPubSubSpec {
+    type SubscriptionId = SubId;
+
+    type Topic = NotificationId<QuoteId>;
+
+    type Event = MintEvent<QuoteId>;
+
+    type Context = DynMintDatabase;
+
+    fn new_instance(context: Self::Context) -> Arc<Self> {
+        Arc::new(Self { db: context })
+    }
+
+    async fn fetch_events(self: &Arc<Self>, topics: Vec<Self::Topic>, reply_to: Subscriber<Self>) {
+        for event in self
+            .get_events_from_db(&topics)
+            .await
+            .inspect_err(|err| tracing::error!("Error reading events from db {err:?}"))
+            .unwrap_or_default()
+        {
+            let _ = reply_to.send(event);
+        }
+    }
+}
+
+/// PubsubManager
+pub struct PubSubManager(Pubsub<MintPubSubSpec>);
+
+impl PubSubManager {
+    /// Create a new instance
+    pub fn new(db: DynMintDatabase) -> Arc<Self> {
+        Arc::new(Self(Pubsub::new(MintPubSubSpec::new_instance(db))))
+    }
+
+    /// Helper function to emit a ProofState status
+    pub fn proof_state<E: Into<ProofState>>(&self, event: E) {
+        self.publish(event.into());
+    }
+
+    /// Helper function to publish even of a mint quote being paid
+    pub fn mint_quote_issue(&self, mint_quote: &MintQuote, total_issued: Amount) {
+        match mint_quote.payment_method {
+            PaymentMethod::Bolt11 => {
+                self.mint_quote_bolt11_status(mint_quote.clone(), MintQuoteState::Issued);
+            }
+            PaymentMethod::Bolt12 => {
+                self.mint_quote_bolt12_status(
+                    mint_quote.clone(),
+                    mint_quote.amount_paid(),
+                    total_issued,
+                );
+            }
+            _ => {
+                // We don't send ws updates for unknown methods
+            }
+        }
+    }
+
+    /// Helper function to publish even of a mint quote being paid
+    pub fn mint_quote_payment(&self, mint_quote: &MintQuote, total_paid: Amount) {
+        match mint_quote.payment_method {
+            PaymentMethod::Bolt11 => {
+                self.mint_quote_bolt11_status(mint_quote.clone(), MintQuoteState::Paid);
+            }
+            PaymentMethod::Bolt12 => {
+                self.mint_quote_bolt12_status(
+                    mint_quote.clone(),
+                    total_paid,
+                    mint_quote.amount_issued(),
+                );
+            }
+            _ => {
+                // We don't send ws updates for unknown methods
+            }
+        }
+    }
+
+    /// Helper function to emit a MintQuoteBolt11Response status
+    pub fn mint_quote_bolt11_status<E: Into<MintQuoteBolt11Response<QuoteId>>>(
+        &self,
+        quote: E,
+        new_state: MintQuoteState,
+    ) {
+        let mut event = quote.into();
+        event.state = new_state;
+
+        self.publish(event);
+    }
+
+    /// Helper function to emit a MintQuoteBolt11Response status
+    pub fn mint_quote_bolt12_status<E: TryInto<MintQuoteBolt12Response<QuoteId>>>(
+        &self,
+        quote: E,
+        amount_paid: Amount,
+        amount_issued: Amount,
+    ) {
+        if let Ok(mut event) = quote.try_into() {
+            event.amount_paid = amount_paid;
+            event.amount_issued = amount_issued;
+
+            self.publish(event);
+        } else {
+            tracing::warn!("Could not convert quote to MintQuoteResponse");
+        }
+    }
+
+    /// Helper function to emit a MeltQuoteBolt11Response status
+    pub fn melt_quote_status<E: Into<MeltQuoteBolt11Response<QuoteId>>>(
+        &self,
+        quote: E,
+        payment_preimage: Option<String>,
+        change: Option<Vec<BlindSignature>>,
+        new_state: MeltQuoteState,
+    ) {
+        let mut quote = quote.into();
+        quote.state = new_state;
+        quote.paid = Some(new_state == MeltQuoteState::Paid);
+        quote.payment_preimage = payment_preimage;
+        quote.change = change;
+        self.publish(quote);
+    }
+}
+
+impl Deref for PubSubManager {
+    type Target = Pubsub<MintPubSubSpec>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}

crates/cdk/src/mint/subscription/manager.rs

@@ -1,292 +0,0 @@
-//! Specific Subscription for the cdk crate
-use std::ops::Deref;
-
-use cdk_common::database::DynMintDatabase;
-use cdk_common::mint::MintQuote;
-use cdk_common::nut17::Notification;
-use cdk_common::quote_id::QuoteId;
-use cdk_common::{Amount, MintQuoteBolt12Response, NotificationPayload, PaymentMethod};
-
-use super::OnSubscription;
-use crate::nuts::{
-    BlindSignature, MeltQuoteBolt11Response, MeltQuoteState, MintQuoteBolt11Response,
-    MintQuoteState, ProofState,
-};
-use crate::pub_sub;
-
-/// Manager
-/// Publish–subscribe manager
-///
-/// Nut-17 implementation is system-wide and not only through the WebSocket, so
-/// it is possible for another part of the system to subscribe to events.
-pub struct PubSubManager(
-    pub_sub::Manager<NotificationPayload<QuoteId>, Notification, OnSubscription>,
-);
-
-#[allow(clippy::default_constructed_unit_structs)]
-impl Default for PubSubManager {
-    fn default() -> Self {
-        PubSubManager(OnSubscription::default().into())
-    }
-}
-
-impl From<DynMintDatabase> for PubSubManager {
-    fn from(val: DynMintDatabase) -> Self {
-        PubSubManager(OnSubscription(Some(val)).into())
-    }
-}
-
-impl Deref for PubSubManager {
-    type Target = pub_sub::Manager<NotificationPayload<QuoteId>, Notification, OnSubscription>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl PubSubManager {
-    /// Helper function to emit a ProofState status
-    pub fn proof_state<E: Into<ProofState>>(&self, event: E) {
-        self.broadcast(event.into().into());
-    }
-
-    /// Helper function to publish even of a mint quote being paid
-    pub fn mint_quote_issue(&self, mint_quote: &MintQuote, total_issued: Amount) {
-        match mint_quote.payment_method {
-            PaymentMethod::Bolt11 => {
-                self.mint_quote_bolt11_status(mint_quote.clone(), MintQuoteState::Issued);
-            }
-            PaymentMethod::Bolt12 => {
-                self.mint_quote_bolt12_status(
-                    mint_quote.clone(),
-                    mint_quote.amount_paid(),
-                    total_issued,
-                );
-            }
-            _ => {
-                // We don't send ws updates for unknown methods
-            }
-        }
-    }
-
-    /// Helper function to publish even of a mint quote being paid
-    pub fn mint_quote_payment(&self, mint_quote: &MintQuote, total_paid: Amount) {
-        match mint_quote.payment_method {
-            PaymentMethod::Bolt11 => {
-                self.mint_quote_bolt11_status(mint_quote.clone(), MintQuoteState::Paid);
-            }
-            PaymentMethod::Bolt12 => {
-                self.mint_quote_bolt12_status(
-                    mint_quote.clone(),
-                    total_paid,
-                    mint_quote.amount_issued(),
-                );
-            }
-            _ => {
-                // We don't send ws updates for unknown methods
-            }
-        }
-    }
-
-    /// Helper function to emit a MintQuoteBolt11Response status
-    pub fn mint_quote_bolt11_status<E: Into<MintQuoteBolt11Response<QuoteId>>>(
-        &self,
-        quote: E,
-        new_state: MintQuoteState,
-    ) {
-        let mut event = quote.into();
-        event.state = new_state;
-
-        self.broadcast(event.into());
-    }
-
-    /// Helper function to emit a MintQuoteBolt11Response status
-    pub fn mint_quote_bolt12_status<E: TryInto<MintQuoteBolt12Response<QuoteId>>>(
-        &self,
-        quote: E,
-        amount_paid: Amount,
-        amount_issued: Amount,
-    ) {
-        if let Ok(mut event) = quote.try_into() {
-            event.amount_paid = amount_paid;
-            event.amount_issued = amount_issued;
-
-            self.broadcast(event.into());
-        } else {
-            tracing::warn!("Could not convert quote to MintQuoteResponse");
-        }
-    }
-
-    /// Helper function to emit a MeltQuoteBolt11Response status
-    pub fn melt_quote_status<E: Into<MeltQuoteBolt11Response<QuoteId>>>(
-        &self,
-        quote: E,
-        payment_preimage: Option<String>,
-        change: Option<Vec<BlindSignature>>,
-        new_state: MeltQuoteState,
-    ) {
-        let mut quote = quote.into();
-        quote.state = new_state;
-        quote.paid = Some(new_state == MeltQuoteState::Paid);
-        quote.payment_preimage = payment_preimage;
-        quote.change = change;
-        self.broadcast(quote.into());
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use std::time::Duration;
-
-    use tokio::time::sleep;
-
-    use super::*;
-    use crate::nuts::nut17::Kind;
-    use crate::nuts::{PublicKey, State};
-    use crate::subscription::{IndexableParams, Params};
-
-    #[tokio::test]
-    async fn active_and_drop() {
-        let manager = PubSubManager::default();
-        let params: IndexableParams = Params {
-            kind: Kind::ProofState,
-            filters: vec![
-                "02a9acc1e48c25eeeb9289b5031cc57da9fe72f3fe2861d264bdc074209b107ba2".to_owned(),
-            ],
-            id: "uno".into(),
-        }
-        .into();
-
-        // Although the same param is used, two subscriptions are created, that
-        // is because each index is unique, thanks to `Unique`, it is the
-        // responsibility of the implementor to make sure that SubId are unique
-        // either globally or per client
-        let subscriptions = vec![
-            manager
-                .try_subscribe(params.clone())
-                .await
-                .expect("valid subscription"),
-            manager
-                .try_subscribe(params)
-                .await
-                .expect("valid subscription"),
-        ];
-        assert_eq!(2, manager.active_subscriptions());
-        drop(subscriptions);
-
-        sleep(Duration::from_millis(10)).await;
-
-        assert_eq!(0, manager.active_subscriptions());
-    }
-
-    #[tokio::test]
-    async fn broadcast() {
-        let manager = PubSubManager::default();
-        let mut subscriptions = [
-            manager
-                .try_subscribe::<IndexableParams>(
-                    Params {
-                        kind: Kind::ProofState,
-                        filters: vec![
-                            "02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104"
-                                .to_string(),
-                        ],
-                        id: "uno".into(),
-                    }
-                    .into(),
-                )
-                .await
-                .expect("valid subscription"),
-            manager
-                .try_subscribe::<IndexableParams>(
-                    Params {
-                        kind: Kind::ProofState,
-                        filters: vec![
-                            "02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104"
-                                .to_string(),
-                        ],
-                        id: "dos".into(),
-                    }
-                    .into(),
-                )
-                .await
-                .expect("valid subscription"),
-        ];
-
-        let event = ProofState {
-            y: PublicKey::from_hex(
-                "02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104",
-            )
-            .expect("valid pk"),
-            state: State::Pending,
-            witness: None,
-        };
-
-        manager.broadcast(event.into());
-
-        sleep(Duration::from_millis(10)).await;
-
-        let (sub1, _) = subscriptions[0].try_recv().expect("valid message");
-        assert_eq!("uno", *sub1);
-
-        let (sub1, _) = subscriptions[1].try_recv().expect("valid message");
-        assert_eq!("dos", *sub1);
-
-        assert!(subscriptions[0].try_recv().is_err());
-        assert!(subscriptions[1].try_recv().is_err());
-    }
-
-    #[test]
-    fn parsing_request() {
-        let json = r#"{"kind":"proof_state","filters":["x"],"subId":"uno"}"#;
-        let params: Params = serde_json::from_str(json).expect("valid json");
-        assert_eq!(params.kind, Kind::ProofState);
-        assert_eq!(params.filters, vec!["x"]);
-        assert_eq!(*params.id, "uno");
-    }
-
-    #[tokio::test]
-    async fn json_test() {
-        let manager = PubSubManager::default();
-        let mut subscription = manager
-            .try_subscribe::<IndexableParams>(
-                serde_json::from_str(r#"{"kind":"proof_state","filters":["02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104"],"subId":"uno"}"#)
-                    .expect("valid json"),
-            )
-            .await.expect("valid subscription");
-
-        manager.broadcast(
-            ProofState {
-                y: PublicKey::from_hex(
-                    "02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104",
-                )
-                .expect("valid pk"),
-                state: State::Pending,
-                witness: None,
-            }
-            .into(),
-        );
-
-        // no one is listening for this event
-        manager.broadcast(
-            ProofState {
-                y: PublicKey::from_hex(
-                    "020000000000000000000000000000000000000000000000000000000000000001",
-                )
-                .expect("valid pk"),
-                state: State::Pending,
-                witness: None,
-            }
-            .into(),
-        );
-
-        sleep(Duration::from_millis(10)).await;
-        let (sub1, msg) = subscription.try_recv().expect("valid message");
-        assert_eq!("uno", *sub1);
-        assert_eq!(
-            r#"{"Y":"02194603ffa36356f4a56b7df9371fc3192472351453ec7398b8da8117e7c3e104","state":"PENDING","witness":null}"#,
-            serde_json::to_string(&msg).expect("valid json")
-        );
-        assert!(subscription.try_recv().is_err());
-    }
-}

crates/cdk/src/mint/subscription/mod.rs

@@ -1,12 +0,0 @@
-//! Specific Subscription for the cdk crate
-
-#[cfg(feature = "mint")]
-mod manager;
-#[cfg(feature = "mint")]
-mod on_subscription;
-#[cfg(feature = "mint")]
-pub use manager::PubSubManager;
-#[cfg(feature = "mint")]
-pub use on_subscription::OnSubscription;
-
-pub use crate::pub_sub::SubId;

crates/cdk/src/mint/subscription/on_subscription.rs

@@ -1,119 +0,0 @@
-//! On Subscription
-//!
-//! This module contains the code that is triggered when a new subscription is created.
-
-use cdk_common::database::DynMintDatabase;
-use cdk_common::nut17::Notification;
-use cdk_common::pub_sub::OnNewSubscription;
-use cdk_common::quote_id::QuoteId;
-use cdk_common::{MintQuoteBolt12Response, NotificationPayload, PaymentMethod};
-
-use crate::nuts::{MeltQuoteBolt11Response, MintQuoteBolt11Response, ProofState, PublicKey};
-
-#[derive(Default)]
-/// Subscription Init
-///
-/// This struct triggers code when a new subscription is created.
-///
-/// It is used to send the initial state of the subscription to the client.
-pub struct OnSubscription(pub(crate) Option<DynMintDatabase>);
-
-#[async_trait::async_trait]
-impl OnNewSubscription for OnSubscription {
-    type Event = NotificationPayload<QuoteId>;
-    type Index = Notification;
-
-    async fn on_new_subscription(
-        &self,
-        request: &[&Self::Index],
-    ) -> Result<Vec<Self::Event>, String> {
-        let datastore = if let Some(localstore) = self.0.as_ref() {
-            localstore
-        } else {
-            return Ok(vec![]);
-        };
-
-        let mut to_return = vec![];
-        let mut public_keys: Vec<PublicKey> = Vec::new();
-        let mut melt_queries = Vec::new();
-        let mut mint_queries = Vec::new();
-
-        for idx in request.iter() {
-            match idx {
-                Notification::ProofState(pk) => public_keys.push(*pk),
-                Notification::MeltQuoteBolt11(uuid) => {
-                    melt_queries.push(datastore.get_melt_quote(uuid))
-                }
-                Notification::MintQuoteBolt11(uuid) => {
-                    mint_queries.push(datastore.get_mint_quote(uuid))
-                }
-                Notification::MintQuoteBolt12(uuid) => {
-                    mint_queries.push(datastore.get_mint_quote(uuid))
-                }
-                Notification::MeltQuoteBolt12(uuid) => {
-                    melt_queries.push(datastore.get_melt_quote(uuid))
-                }
-            }
-        }
-
-        if !melt_queries.is_empty() {
-            to_return.extend(
-                futures::future::try_join_all(melt_queries)
-                    .await
-                    .map(|quotes| {
-                        quotes
-                            .into_iter()
-                            .filter_map(|quote| quote.map(|x| x.into()))
-                            .map(|x: MeltQuoteBolt11Response<QuoteId>| x.into())
-                            .collect::<Vec<_>>()
-                    })
-                    .map_err(|e| e.to_string())?,
-            );
-        }
-
-        if !mint_queries.is_empty() {
-            to_return.extend(
-                futures::future::try_join_all(mint_queries)
-                    .await
-                    .map(|quotes| {
-                        quotes
-                            .into_iter()
-                            .filter_map(|quote| {
-                                quote.and_then(|x| match x.payment_method {
-                                    PaymentMethod::Bolt11 => {
-                                        let response: MintQuoteBolt11Response<QuoteId> = x.into();
-                                        Some(response.into())
-                                    }
-                                    PaymentMethod::Bolt12 => match x.try_into() {
-                                        Ok(response) => {
-                                            let response: MintQuoteBolt12Response<QuoteId> =
-                                                response;
-                                            Some(response.into())
-                                        }
-                                        Err(_) => None,
-                                    },
-                                    PaymentMethod::Custom(_) => None,
-                                })
-                            })
-                            .collect::<Vec<_>>()
-                    })
-                    .map_err(|e| e.to_string())?,
-            );
-        }
-
-        if !public_keys.is_empty() {
-            to_return.extend(
-                datastore
-                    .get_proofs_states(public_keys.as_slice())
-                    .await
-                    .map_err(|e| e.to_string())?
-                    .into_iter()
-                    .enumerate()
-                    .filter_map(|(idx, state)| state.map(|state| (public_keys[idx], state).into()))
-                    .map(|state: ProofState| state.into()),
-            );
-        }
-
-        Ok(to_return)
-    }
-}

crates/cdk/src/pub_sub.rs

@@ -1,339 +0,0 @@
-//! Publish–subscribe pattern.
-//!
-//! This is a generic implementation for
-//! [NUT-17](<https://github.com/cashubtc/nuts/blob/main/17.md>) with a type
-//! agnostic Publish-subscribe manager.
-//!
-//! The manager has a method for subscribers to subscribe to events with a
-//! generic type that must be converted to a vector of indexes.
-//!
-//! Events are also generic that should implement the `Indexable` trait.
-use std::cmp::Ordering;
-use std::collections::{BTreeMap, HashSet};
-use std::fmt::Debug;
-use std::ops::{Deref, DerefMut};
-use std::sync::atomic::{self, AtomicUsize};
-use std::sync::Arc;
-
-pub use cdk_common::pub_sub::index::{Index, Indexable, SubscriptionGlobalId};
-use cdk_common::pub_sub::OnNewSubscription;
-pub use cdk_common::pub_sub::SubId;
-use tokio::sync::{mpsc, RwLock};
-use tokio::task::JoinHandle;
-
-type IndexTree<T, I> = Arc<RwLock<BTreeMap<Index<I>, mpsc::Sender<(SubId, T)>>>>;
-
-/// Default size of the remove channel
-pub const DEFAULT_REMOVE_SIZE: usize = 10_000;
-
-/// Default channel size for subscription buffering
-pub const DEFAULT_CHANNEL_SIZE: usize = 10;
-
-/// Subscription manager
-///
-/// This object keep track of all subscription listener and it is also
-/// responsible for broadcasting events to all listeners
-///
-/// The content of the notification is not relevant to this scope and it is up
-/// to the application, therefore the generic T is used instead of a specific
-/// type
-pub struct Manager<T, I, F>
-where
-    T: Indexable<Type = I> + Clone + Send + Sync + 'static,
-    I: PartialOrd + Clone + Debug + Ord + Send + Sync + 'static,
-    F: OnNewSubscription<Index = I, Event = T> + Send + Sync + 'static,
-{
-    indexes: IndexTree<T, I>,
-    on_new_subscription: Option<Arc<F>>,
-    unsubscription_sender: mpsc::Sender<(SubId, Vec<Index<I>>)>,
-    active_subscriptions: Arc<AtomicUsize>,
-    background_subscription_remover: Option<JoinHandle<()>>,
-}
-
-impl<T, I, F> Default for Manager<T, I, F>
-where
-    T: Indexable<Type = I> + Clone + Send + Sync + 'static,
-    I: PartialOrd + Clone + Debug + Ord + Send + Sync + 'static,
-    F: OnNewSubscription<Index = I, Event = T> + Send + Sync + 'static,
-{
-    fn default() -> Self {
-        let (sender, receiver) = mpsc::channel(DEFAULT_REMOVE_SIZE);
-        let active_subscriptions: Arc<AtomicUsize> = Default::default();
-        let storage: IndexTree<T, I> = Arc::new(Default::default());
-
-        Self {
-            background_subscription_remover: Some(tokio::spawn(Self::remove_subscription(
-                receiver,
-                storage.clone(),
-                active_subscriptions.clone(),
-            ))),
-            on_new_subscription: None,
-            unsubscription_sender: sender,
-            active_subscriptions,
-            indexes: storage,
-        }
-    }
-}
-
-impl<T, I, F> From<F> for Manager<T, I, F>
-where
-    T: Indexable<Type = I> + Clone + Send + Sync + 'static,
-    I: PartialOrd + Clone + Debug + Ord + Send + Sync + 'static,
-    F: OnNewSubscription<Index = I, Event = T> + Send + Sync + 'static,
-{
-    fn from(value: F) -> Self {
-        let mut manager: Self = Default::default();
-        manager.on_new_subscription = Some(Arc::new(value));
-        manager
-    }
-}
-
-impl<T, I, F> Manager<T, I, F>
-where
-    T: Indexable<Type = I> + Clone + Send + Sync + 'static,
-    I: PartialOrd + Clone + Debug + Ord + Send + Sync + 'static,
-    F: OnNewSubscription<Index = I, Event = T> + Send + Sync + 'static,
-{
-    #[inline]
-    /// Broadcast an event to all listeners
-    ///
-    /// This function takes an Arc to the storage struct, the event_id, the kind
-    /// and the vent to broadcast
-    async fn broadcast_impl(storage: &IndexTree<T, I>, event: T) {
-        let index_storage = storage.read().await;
-        let mut sent = HashSet::new();
-        for index in event.to_indexes() {
-            for (key, sender) in index_storage.range(index.clone()..) {
-                if index.cmp_prefix(key) != Ordering::Equal {
-                    break;
-                }
-                let sub_id = key.unique_id();
-                if sent.contains(&sub_id) {
-                    continue;
-                }
-                sent.insert(sub_id);
-                let _ = sender.try_send((key.into(), event.clone()));
-            }
-        }
-    }
-
-    /// Broadcasts an event to all listeners
-    ///
-    /// This public method will not block the caller, it will spawn a new task
-    /// instead
-    pub fn broadcast(&self, event: T) {
-        let storage = self.indexes.clone();
-        tokio::spawn(async move {
-            Self::broadcast_impl(&storage, event).await;
-        });
-    }
-
-    /// Broadcasts an event to all listeners
-    ///
-    /// This method is async and will await for the broadcast to be completed
-    pub async fn broadcast_async(&self, event: T) {
-        Self::broadcast_impl(&self.indexes, event).await;
-    }
-
-    /// Specific of the subscription, this is the abstraction between `subscribe` and `try_subscribe`
-    #[inline(always)]
-    async fn subscribe_inner(
-        &self,
-        sub_id: SubId,
-        indexes: Vec<Index<I>>,
-    ) -> ActiveSubscription<T, I> {
-        let (sender, receiver) = mpsc::channel(10);
-
-        let mut index_storage = self.indexes.write().await;
-        // Subscribe to events as soon as possible
-        for index in indexes.clone() {
-            index_storage.insert(index, sender.clone());
-        }
-        drop(index_storage);
-
-        if let Some(on_new_subscription) = self.on_new_subscription.clone() {
-            // After we're subscribed already, fetch the current status of matching events. It is
-            // down in another thread to return right away
-            let indexes_for_worker = indexes.clone();
-            let sub_id_for_worker = sub_id.clone();
-            tokio::spawn(async move {
-                match on_new_subscription
-                    .on_new_subscription(
-                        &indexes_for_worker
-                            .iter()
-                            .map(|x| x.deref())
-                            .collect::<Vec<_>>(),
-                    )
-                    .await
-                {
-                    Ok(events) => {
-                        for event in events {
-                            let _ = sender.try_send((sub_id_for_worker.clone(), event));
-                        }
-                    }
-                    Err(err) => {
-                        tracing::info!(
-                            "Failed to get initial state for subscription: {:?}, {}",
-                            sub_id_for_worker,
-                            err
-                        );
-                    }
-                }
-            });
-        }
-
-        self.active_subscriptions
-            .fetch_add(1, atomic::Ordering::Relaxed);
-
-        ActiveSubscription {
-            sub_id,
-            receiver,
-            indexes,
-            drop: self.unsubscription_sender.clone(),
-        }
-    }
-
-    /// Try to subscribe to a specific event
-    pub async fn try_subscribe<P>(&self, params: P) -> Result<ActiveSubscription<T, I>, P::Error>
-    where
-        P: AsRef<SubId> + TryInto<Vec<Index<I>>>,
-    {
-        Ok(self
-            .subscribe_inner(params.as_ref().clone(), params.try_into()?)
-            .await)
-    }
-
-    /// Subscribe to a specific event
-    pub async fn subscribe<P>(&self, params: P) -> ActiveSubscription<T, I>
-    where
-        P: AsRef<SubId> + Into<Vec<Index<I>>>,
-    {
-        self.subscribe_inner(params.as_ref().clone(), params.into())
-            .await
-    }
-
-    /// Return number of active subscriptions
-    pub fn active_subscriptions(&self) -> usize {
-        self.active_subscriptions.load(atomic::Ordering::SeqCst)
-    }
-
-    /// Task to remove dropped subscriptions from the storage struct
-    ///
-    /// This task will run in the background (and will be dropped when the [`Manager`]
-    /// is) and will remove subscriptions from the storage struct it is dropped.
-    async fn remove_subscription(
-        mut receiver: mpsc::Receiver<(SubId, Vec<Index<I>>)>,
-        storage: IndexTree<T, I>,
-        active_subscriptions: Arc<AtomicUsize>,
-    ) {
-        while let Some((sub_id, indexes)) = receiver.recv().await {
-            tracing::info!("Removing subscription: {}", *sub_id);
-
-            active_subscriptions.fetch_sub(1, atomic::Ordering::AcqRel);
-
-            let mut index_storage = storage.write().await;
-            for key in indexes {
-                index_storage.remove(&key);
-            }
-            drop(index_storage);
-        }
-    }
-}
-
-/// Manager goes out of scope, stop all background tasks
-impl<T, I, F> Drop for Manager<T, I, F>
-where
-    T: Indexable<Type = I> + Clone + Send + Sync + 'static,
-    I: Clone + Debug + PartialOrd + Ord + Send + Sync + 'static,
-    F: OnNewSubscription<Index = I, Event = T> + Send + Sync + 'static,
-{
-    fn drop(&mut self) {
-        if let Some(handler) = self.background_subscription_remover.take() {
-            handler.abort();
-        }
-    }
-}
-
-/// Active Subscription
-///
-/// This struct is a wrapper around the `mpsc::Receiver<Event>` and it also used
-/// to keep track of the subscription itself. When this struct goes out of
-/// scope, it will notify the Manager about it, so it can be removed from the
-/// list of active listeners
-pub struct ActiveSubscription<T, I>
-where
-    T: Send + Sync,
-    I: Clone + Debug + PartialOrd + Ord + Send + Sync + 'static,
-{
-    /// The subscription ID
-    pub sub_id: SubId,
-    indexes: Vec<Index<I>>,
-    receiver: mpsc::Receiver<(SubId, T)>,
-    drop: mpsc::Sender<(SubId, Vec<Index<I>>)>,
-}
-
-impl<T, I> Deref for ActiveSubscription<T, I>
-where
-    T: Send + Sync,
-    I: Clone + Debug + PartialOrd + Ord + Send + Sync + 'static,
-{
-    type Target = mpsc::Receiver<(SubId, T)>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.receiver
-    }
-}
-
-impl<T, I> DerefMut for ActiveSubscription<T, I>
-where
-    T: Indexable + Clone + Send + Sync + 'static,
-    I: Clone + Debug + PartialOrd + Ord + Send + Sync + 'static,
-{
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.receiver
-    }
-}
-
-/// The ActiveSubscription is Drop out of scope, notify the Manager about it, so
-/// it can be removed from the list of active listeners
-///
-/// Having this in place, we can avoid memory leaks and also makes it super
-/// simple to implement the Unsubscribe method
-impl<T, I> Drop for ActiveSubscription<T, I>
-where
-    T: Send + Sync,
-    I: Clone + Debug + PartialOrd + Ord + Send + Sync + 'static,
-{
-    fn drop(&mut self) {
-        let _ = self
-            .drop
-            .try_send((self.sub_id.clone(), self.indexes.drain(..).collect()));
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use tokio::sync::mpsc;
-
-    use super::*;
-
-    #[test]
-    fn test_active_subscription_drop() {
-        let (tx, rx) = mpsc::channel::<(SubId, ())>(10);
-        let sub_id = SubId::from("test_sub_id");
-        let indexes: Vec<Index<String>> = vec![Index::from(("test".to_string(), sub_id.clone()))];
-        let (drop_tx, mut drop_rx) = mpsc::channel(10);
-
-        {
-            let _active_subscription = ActiveSubscription {
-                sub_id: sub_id.clone(),
-                indexes,
-                receiver: rx,
-                drop: drop_tx,
-            };
-            // When it goes out of scope, it should notify
-        }
-        assert_eq!(drop_rx.try_recv().unwrap().0, sub_id); // it should have notified
-        assert!(tx.try_send(("foo".into(), ())).is_err()); // subscriber is dropped
-    }
-}

crates/cdk/src/wallet/mod.rs

@@ -6,7 +6,7 @@ use std::sync::Arc;
 
 use cdk_common::amount::FeeAndAmounts;
 use cdk_common::database::{self, WalletDatabase};
-use cdk_common::subscription::Params;
+use cdk_common::subscription::WalletParams;
 use getrandom::getrandom;
 use subscription::{ActiveSubscription, SubscriptionManager};
 #[cfg(feature = "auth")]
@@ -108,40 +108,42 @@ pub enum WalletSubscription {
     Bolt12MintQuoteState(Vec<String>),
 }
 
-impl From<WalletSubscription> for Params {
+impl From<WalletSubscription> for WalletParams {
     fn from(val: WalletSubscription) -> Self {
         let mut buffer = vec![0u8; 10];
 
         getrandom(&mut buffer).expect("Failed to generate random bytes");
 
-        let id = buffer
+        let id = Arc::new(
+            buffer
                 .iter()
                 .map(|&byte| {
                     let index = byte as usize % ALPHANUMERIC.len(); // 62 alphanumeric characters (A-Z, a-z, 0-9)
                     ALPHANUMERIC[index] as char
                 })
-            .collect::<String>();
+                .collect::<String>(),
+        );
 
         match val {
-            WalletSubscription::ProofState(filters) => Params {
+            WalletSubscription::ProofState(filters) => WalletParams {
                 filters,
                 kind: Kind::ProofState,
-                id: id.into(),
+                id,
             },
-            WalletSubscription::Bolt11MintQuoteState(filters) => Params {
+            WalletSubscription::Bolt11MintQuoteState(filters) => WalletParams {
                 filters,
                 kind: Kind::Bolt11MintQuote,
-                id: id.into(),
+                id,
             },
-            WalletSubscription::Bolt11MeltQuoteState(filters) => Params {
+            WalletSubscription::Bolt11MeltQuoteState(filters) => WalletParams {
                 filters,
                 kind: Kind::Bolt11MeltQuote,
-                id: id.into(),
+                id,
             },
-            WalletSubscription::Bolt12MintQuoteState(filters) => Params {
+            WalletSubscription::Bolt12MintQuoteState(filters) => WalletParams {
                 filters,
                 kind: Kind::Bolt12MintQuote,
-                id: id.into(),
+                id,
             },
         }
     }
@@ -193,10 +195,10 @@ impl Wallet {
     }
 
     /// Subscribe to events
-    pub async fn subscribe<T: Into<Params>>(&self, query: T) -> ActiveSubscription {
+    pub async fn subscribe<T: Into<WalletParams>>(&self, query: T) -> ActiveSubscription {
         self.subscription
-            .subscribe(self.mint_url.clone(), query.into(), Arc::new(self.clone()))
+            .subscribe(self.mint_url.clone(), query.into())
-            .await
+            .expect("FIXME")
     }
 
     /// Fee required for proof set

crates/cdk/src/wallet/multi_mint_wallet.rs

@@ -4,6 +4,7 @@
 //! pairs
 
 use std::collections::BTreeMap;
+use std::ops::Deref;
 use std::str::FromStr;
 use std::sync::Arc;
 
@@ -675,7 +676,7 @@ impl MultiMintWallet {
                     // Check if this is a mint quote response with paid state
                     if let crate::nuts::nut17::NotificationPayload::MintQuoteBolt11Response(
                         quote_response,
-                    ) = notification
+                    ) = notification.deref()
                     {
                         if quote_response.state == QuoteState::Paid {
                             // Quote is paid, now mint the tokens

crates/cdk/src/wallet/streams/payment.rs

@@ -13,10 +13,11 @@ use futures::{FutureExt, Stream, StreamExt};
 use tokio_util::sync::CancellationToken;
 
 use super::RecvFuture;
+use crate::event::MintEvent;
 use crate::wallet::subscription::ActiveSubscription;
 use crate::{Wallet, WalletSubscription};
 
-type SubscribeReceived = (Option<NotificationPayload<String>>, Vec<ActiveSubscription>);
+type SubscribeReceived = (Option<MintEvent<String>>, Vec<ActiveSubscription>);
 type PaymentValue = (String, Option<Amount>);
 
 /// PaymentWaiter
@@ -145,7 +146,7 @@ impl<'a> PaymentStream<'a> {
                         Poll::Ready(None)
                     }
                     Some(info) => {
-                        match info {
+                        match info.into_inner() {
                             NotificationPayload::MintQuoteBolt11Response(info) => {
                                 if info.state == MintQuoteState::Paid {
                                     self.is_finalized = true;

crates/cdk/src/wallet/subscription/http.rs

@@ -1,238 +0,0 @@
-use std::collections::HashMap;
-use std::sync::Arc;
-
-use cdk_common::MintQuoteBolt12Response;
-use tokio::sync::{mpsc, RwLock};
-#[cfg(not(target_arch = "wasm32"))]
-use tokio::time;
-use web_time::Duration;
-
-use super::WsSubscriptionBody;
-use crate::nuts::nut17::Kind;
-use crate::nuts::{nut01, nut05, nut07, nut23, CheckStateRequest, NotificationPayload};
-use crate::pub_sub::SubId;
-use crate::wallet::MintConnector;
-use crate::Wallet;
-
-#[derive(Debug, Hash, PartialEq, Eq)]
-enum UrlType {
-    Mint(String),
-    MintBolt12(String),
-    Melt(String),
-    PublicKey(nut01::PublicKey),
-}
-
-#[derive(Debug, Eq, PartialEq)]
-enum AnyState {
-    MintQuoteState(nut23::QuoteState),
-    MintBolt12QuoteState(MintQuoteBolt12Response<String>),
-    MeltQuoteState(nut05::QuoteState),
-    PublicKey(nut07::State),
-    Empty,
-}
-
-type SubscribedTo = HashMap<UrlType, (mpsc::Sender<NotificationPayload<String>>, SubId, AnyState)>;
-
-async fn convert_subscription(
-    sub_id: SubId,
-    subscriptions: &Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
-    subscribed_to: &mut SubscribedTo,
-) -> Option<()> {
-    let subscription = subscriptions.read().await;
-    let sub = subscription.get(&sub_id)?;
-    tracing::debug!("New subscription: {:?}", sub);
-    match sub.1.kind {
-        Kind::Bolt11MintQuote => {
-            for id in sub.1.filters.iter().map(|id| UrlType::Mint(id.clone())) {
-                subscribed_to.insert(id, (sub.0.clone(), sub.1.id.clone(), AnyState::Empty));
-            }
-        }
-        Kind::Bolt11MeltQuote => {
-            for id in sub.1.filters.iter().map(|id| UrlType::Melt(id.clone())) {
-                subscribed_to.insert(id, (sub.0.clone(), sub.1.id.clone(), AnyState::Empty));
-            }
-        }
-        Kind::ProofState => {
-            for id in sub
-                .1
-                .filters
-                .iter()
-                .map(|id| nut01::PublicKey::from_hex(id).map(UrlType::PublicKey))
-            {
-                match id {
-                    Ok(id) => {
-                        subscribed_to
-                            .insert(id, (sub.0.clone(), sub.1.id.clone(), AnyState::Empty));
-                    }
-                    Err(err) => {
-                        tracing::error!("Error parsing public key: {:?}. Subscription ignored, will never yield any result", err);
-                    }
-                }
-            }
-        }
-        Kind::Bolt12MintQuote => {
-            for id in sub
-                .1
-                .filters
-                .iter()
-                .map(|id| UrlType::MintBolt12(id.clone()))
-            {
-                subscribed_to.insert(id, (sub.0.clone(), sub.1.id.clone(), AnyState::Empty));
-            }
-        }
-    }
-
-    Some(())
-}
-
-#[cfg(not(target_arch = "wasm32"))]
-#[inline]
-pub async fn http_main<S: IntoIterator<Item = SubId>>(
-    initial_state: S,
-    http_client: Arc<dyn MintConnector + Send + Sync>,
-    subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
-    mut new_subscription_recv: mpsc::Receiver<SubId>,
-    mut on_drop: mpsc::Receiver<SubId>,
-    _wallet: Arc<Wallet>,
-) {
-    let mut interval = time::interval(Duration::from_secs(2));
-    let mut subscribed_to = SubscribedTo::new();
-
-    for sub_id in initial_state {
-        convert_subscription(sub_id, &subscriptions, &mut subscribed_to).await;
-    }
-
-    loop {
-        tokio::select! {
-            _ = interval.tick() => {
-                poll_subscriptions(&http_client, &mut subscribed_to).await;
-            }
-            Some(subid) = new_subscription_recv.recv() => {
-                convert_subscription(subid, &subscriptions, &mut subscribed_to).await;
-            }
-            Some(id) = on_drop.recv() => {
-                subscribed_to.retain(|_, (_, sub_id, _)| *sub_id != id);
-            }
-        }
-    }
-}
-
-#[cfg(target_arch = "wasm32")]
-#[inline]
-pub async fn http_main<S: IntoIterator<Item = SubId>>(
-    initial_state: S,
-    http_client: Arc<dyn MintConnector + Send + Sync>,
-    subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
-    mut new_subscription_recv: mpsc::Receiver<SubId>,
-    mut on_drop: mpsc::Receiver<SubId>,
-    _wallet: Arc<Wallet>,
-) {
-    let mut subscribed_to = SubscribedTo::new();
-
-    for sub_id in initial_state {
-        convert_subscription(sub_id, &subscriptions, &mut subscribed_to).await;
-    }
-
-    loop {
-        tokio::select! {
-            _ = gloo_timers::future::sleep(Duration::from_secs(2)) => {
-                poll_subscriptions(&http_client, &mut subscribed_to).await;
-            }
-            subid = new_subscription_recv.recv() => {
-                match subid {
-                    Some(subid) => {
-                        convert_subscription(subid, &subscriptions, &mut subscribed_to).await;
-                    }
-                    None => {
-                        // New subscription channel closed - SubscriptionClient was dropped, terminate worker
-                        break;
-                    }
-                }
-            }
-            id = on_drop.recv() => {
-                match id {
-                    Some(id) => {
-                        subscribed_to.retain(|_, (_, sub_id, _)| *sub_id != id);
-                    }
-                    None => {
-                        // Drop notification channel closed - SubscriptionClient was dropped, terminate worker
-                        break;
-                    }
-                }
-            }
-        }
-    }
-}
-
-async fn poll_subscriptions(
-    http_client: &Arc<dyn MintConnector + Send + Sync>,
-    subscribed_to: &mut SubscribedTo,
-) {
-    for (url, (sender, _, last_state)) in subscribed_to.iter_mut() {
-        tracing::debug!("Polling: {:?}", url);
-        match url {
-            UrlType::MintBolt12(id) => {
-                let response = http_client.get_mint_quote_bolt12_status(id).await;
-                if let Ok(response) = response {
-                    if *last_state == AnyState::MintBolt12QuoteState(response.clone()) {
-                        continue;
-                    }
-                    *last_state = AnyState::MintBolt12QuoteState(response.clone());
-                    if let Err(err) =
-                        sender.try_send(NotificationPayload::MintQuoteBolt12Response(response))
-                    {
-                        tracing::error!("Error sending mint quote response: {:?}", err);
-                    }
-                }
-            }
-            UrlType::Mint(id) => {
-                let response = http_client.get_mint_quote_status(id).await;
-                if let Ok(response) = response {
-                    if *last_state == AnyState::MintQuoteState(response.state) {
-                        continue;
-                    }
-                    *last_state = AnyState::MintQuoteState(response.state);
-                    if let Err(err) =
-                        sender.try_send(NotificationPayload::MintQuoteBolt11Response(response))
-                    {
-                        tracing::error!("Error sending mint quote response: {:?}", err);
-                    }
-                }
-            }
-            UrlType::Melt(id) => {
-                let response = http_client.get_melt_quote_status(id).await;
-                if let Ok(response) = response {
-                    if *last_state == AnyState::MeltQuoteState(response.state) {
-                        continue;
-                    }
-                    *last_state = AnyState::MeltQuoteState(response.state);
-                    if let Err(err) =
-                        sender.try_send(NotificationPayload::MeltQuoteBolt11Response(response))
-                    {
-                        tracing::error!("Error sending melt quote response: {:?}", err);
-                    }
-                }
-            }
-            UrlType::PublicKey(id) => {
-                let responses = http_client
-                    .post_check_state(CheckStateRequest { ys: vec![*id] })
-                    .await;
-                if let Ok(mut responses) = responses {
-                    let response = if let Some(state) = responses.states.pop() {
-                        state
-                    } else {
-                        continue;
-                    };
-
-                    if *last_state == AnyState::PublicKey(response.state) {
-                        continue;
-                    }
-                    *last_state = AnyState::PublicKey(response.state);
-                    if let Err(err) = sender.try_send(NotificationPayload::ProofState(response)) {
-                        tracing::error!("Error sending proof state response: {:?}", err);
-                    }
-                }
-            }
-        }
-    }
-}

crates/cdk/src/wallet/subscription/mod.rs

@@ -7,28 +7,33 @@
 //! the HTTP client.
 use std::collections::HashMap;
 use std::fmt::Debug;
+use std::sync::atomic::AtomicUsize;
 use std::sync::Arc;
 
-use cdk_common::subscription::Params;
+use cdk_common::nut17::ws::{WsMethodRequest, WsRequest, WsUnsubscribeRequest};
-use tokio::sync::{mpsc, RwLock};
+use cdk_common::nut17::{Kind, NotificationId};
-use tokio::task::JoinHandle;
+use cdk_common::parking_lot::RwLock;
-#[cfg(target_arch = "wasm32")]
+use cdk_common::pub_sub::remote_consumer::{
-use wasm_bindgen_futures;
+    Consumer, InternalRelay, RemoteActiveConsumer, StreamCtrl, SubscribeMessage, Transport,
+};
+use cdk_common::pub_sub::{Error as PubsubError, Spec, Subscriber};
+use cdk_common::subscription::WalletParams;
+use cdk_common::CheckStateRequest;
+use tokio::sync::mpsc;
+use uuid::Uuid;
 
-use super::Wallet;
+use crate::event::MintEvent;
 use crate::mint_url::MintUrl;
-use crate::pub_sub::SubId;
 use crate::wallet::MintConnector;
 
-mod http;
+#[cfg(not(target_arch = "wasm32"))]
-#[cfg(all(
-    not(feature = "http_subscription"),
-    feature = "mint",
-    not(target_arch = "wasm32")
-))]
 mod ws;
 
-type WsSubscriptionBody = (mpsc::Sender<NotificationPayload>, Params);
+/// Notification Payload
+pub type NotificationPayload = crate::nuts::NotificationPayload<String>;
+
+/// Type alias
+pub type ActiveSubscription = RemoteActiveConsumer<SubscriptionClient>;
 
 /// Subscription manager
 ///
@@ -45,13 +50,27 @@ type WsSubscriptionBody = (mpsc::Sender<NotificationPayload>, Params);
 /// The subscribers have a simple-to-use interface, receiving an
 /// ActiveSubscription struct, which can be used to receive updates and to
 /// unsubscribe from updates automatically on the drop.
-#[derive(Debug, Clone)]
+#[derive(Clone)]
 pub struct SubscriptionManager {
-    all_connections: Arc<RwLock<HashMap<MintUrl, SubscriptionClient>>>,
+    all_connections: Arc<RwLock<HashMap<MintUrl, Arc<Consumer<SubscriptionClient>>>>>,
     http_client: Arc<dyn MintConnector + Send + Sync>,
     prefer_http: bool,
 }
 
+impl Debug for SubscriptionManager {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Subscription Manager connected to {:?}",
+            self.all_connections
+                .write()
+                .keys()
+                .cloned()
+                .collect::<Vec<_>>()
+        )
+    }
+}
+
 impl SubscriptionManager {
     /// Create a new subscription manager
     pub fn new(http_client: Arc<dyn MintConnector + Send + Sync>, prefer_http: bool) -> Self {
@@ -63,64 +82,55 @@ impl SubscriptionManager {
     }
 
     /// Subscribe to updates from a mint server with a given filter
-    pub async fn subscribe(
+    pub fn subscribe(
         &self,
         mint_url: MintUrl,
-        filter: Params,
+        filter: WalletParams,
-        wallet: Arc<Wallet>,
+    ) -> Result<RemoteActiveConsumer<SubscriptionClient>, PubsubError> {
-    ) -> ActiveSubscription {
+        self.all_connections
-        let subscription_clients = self.all_connections.read().await;
+            .write()
-        let id = filter.id.clone();
+            .entry(mint_url.clone())
-        if let Some(subscription_client) = subscription_clients.get(&mint_url) {
+            .or_insert_with(|| {
-            let (on_drop_notif, receiver) = subscription_client.subscribe(filter).await;
+                Consumer::new(
-            ActiveSubscription::new(receiver, id, on_drop_notif)
+                    SubscriptionClient {
-        } else {
-            drop(subscription_clients);
-
-            #[cfg(all(
-                not(feature = "http_subscription"),
-                feature = "mint",
-                not(target_arch = "wasm32")
-            ))]
-            let is_ws_support = self
-                .http_client
-                .get_mint_info()
-                .await
-                .map(|info| !info.nuts.nut17.supported.is_empty())
-                .unwrap_or_default();
-
-            #[cfg(any(
-                feature = "http_subscription",
-                not(feature = "mint"),
-                target_arch = "wasm32"
-            ))]
-            let is_ws_support = false;
-
-            let is_ws_support = if self.prefer_http {
-                false
-            } else {
-                is_ws_support
-            };
-
-            tracing::debug!(
-                "Connect to {:?} to subscribe. WebSocket is supported ({})",
                         mint_url,
-                is_ws_support
+                        http_client: self.http_client.clone(),
-            );
+                        req_id: 0.into(),
-
+                    },
-            let mut subscription_clients = self.all_connections.write().await;
+                    self.prefer_http,
-            let subscription_client = SubscriptionClient::new(
+                    (),
-                mint_url.clone(),
+                )
-                self.http_client.clone(),
+            })
-                is_ws_support,
+            .subscribe(filter)
-                wallet,
-            );
-            let (on_drop_notif, receiver) = subscription_client.subscribe(filter).await;
-            subscription_clients.insert(mint_url, subscription_client);
-
-            ActiveSubscription::new(receiver, id, on_drop_notif)
     }
 }
+
+/// MintSubTopics
+#[derive(Clone, Default)]
+pub struct MintSubTopics {}
+
+#[async_trait::async_trait]
+impl Spec for MintSubTopics {
+    type SubscriptionId = String;
+
+    type Event = MintEvent<String>;
+
+    type Topic = NotificationId<String>;
+
+    type Context = ();
+
+    fn new_instance(_context: Self::Context) -> Arc<Self>
+    where
+        Self: Sized,
+    {
+        Arc::new(Self {})
+    }
+
+    async fn fetch_events(self: &Arc<Self>, _topics: Vec<Self::Topic>, _reply_to: Subscriber<Self>)
+    where
+        Self: Sized,
+    {
+    }
 }
 
 /// Subscription client
@@ -129,225 +139,178 @@ impl SubscriptionManager {
 /// otherwise the HTTP pool and pause will be used (which is the less efficient
 /// method).
 #[derive(Debug)]
+#[allow(dead_code)]
 pub struct SubscriptionClient {
-    new_subscription_notif: mpsc::Sender<SubId>,
+    http_client: Arc<dyn MintConnector + Send + Sync>,
-    on_drop_notif: mpsc::Sender<SubId>,
+    mint_url: MintUrl,
-    subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
+    req_id: AtomicUsize,
-    worker: Option<JoinHandle<()>>,
-}
-
-type NotificationPayload = crate::nuts::NotificationPayload<String>;
-
-/// Active Subscription
-pub struct ActiveSubscription {
-    sub_id: Option<SubId>,
-    on_drop_notif: mpsc::Sender<SubId>,
-    receiver: mpsc::Receiver<NotificationPayload>,
-}
-
-impl ActiveSubscription {
-    fn new(
-        receiver: mpsc::Receiver<NotificationPayload>,
-        sub_id: SubId,
-        on_drop_notif: mpsc::Sender<SubId>,
-    ) -> Self {
-        Self {
-            sub_id: Some(sub_id),
-            on_drop_notif,
-            receiver,
-        }
-    }
-
-    /// Try to receive a notification
-    pub fn try_recv(&mut self) -> Result<Option<NotificationPayload>, Error> {
-        match self.receiver.try_recv() {
-            Ok(payload) => Ok(Some(payload)),
-            Err(mpsc::error::TryRecvError::Empty) => Ok(None),
-            Err(mpsc::error::TryRecvError::Disconnected) => Err(Error::Disconnected),
-        }
-    }
-
-    /// Receive a notification asynchronously
-    pub async fn recv(&mut self) -> Option<NotificationPayload> {
-        self.receiver.recv().await
-    }
-}
-
-impl Drop for ActiveSubscription {
-    fn drop(&mut self) {
-        if let Some(sub_id) = self.sub_id.take() {
-            let _ = self.on_drop_notif.try_send(sub_id);
-        }
-    }
-}
-
-/// Subscription client error
-#[derive(thiserror::Error, Debug)]
-pub enum Error {
-    /// Url error
-    #[error("Could not join paths: {0}")]
-    Url(#[from] crate::mint_url::Error),
-    /// Disconnected from the notification channel
-    #[error("Disconnected from the notification channel")]
-    Disconnected,
 }
 
+#[allow(dead_code)]
 impl SubscriptionClient {
-    /// Create new [`SubscriptionClient`]
+    fn get_sub_request(
-    pub fn new(
-        url: MintUrl,
-        http_client: Arc<dyn MintConnector + Send + Sync>,
-        prefer_ws_method: bool,
-        wallet: Arc<Wallet>,
-    ) -> Self {
-        let subscriptions = Arc::new(RwLock::new(HashMap::new()));
-        let (new_subscription_notif, new_subscription_recv) = mpsc::channel(100);
-        let (on_drop_notif, on_drop_recv) = mpsc::channel(1000);
-
-        Self {
-            new_subscription_notif,
-            on_drop_notif,
-            subscriptions: subscriptions.clone(),
-            worker: Self::start_worker(
-                prefer_ws_method,
-                http_client,
-                url,
-                subscriptions,
-                new_subscription_recv,
-                on_drop_recv,
-                wallet,
-            ),
-        }
-    }
-
-    #[allow(unused_variables)]
-    fn start_worker(
-        prefer_ws_method: bool,
-        http_client: Arc<dyn MintConnector + Send + Sync>,
-        url: MintUrl,
-        subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
-        new_subscription_recv: mpsc::Receiver<SubId>,
-        on_drop_recv: mpsc::Receiver<SubId>,
-        wallet: Arc<Wallet>,
-    ) -> Option<JoinHandle<()>> {
-        #[cfg(any(
-            feature = "http_subscription",
-            not(feature = "mint"),
-            target_arch = "wasm32"
-        ))]
-        return Self::http_worker(
-            http_client,
-            subscriptions,
-            new_subscription_recv,
-            on_drop_recv,
-            wallet,
-        );
-
-        #[cfg(all(
-            not(feature = "http_subscription"),
-            feature = "mint",
-            not(target_arch = "wasm32")
-        ))]
-        if prefer_ws_method {
-            Self::ws_worker(
-                http_client,
-                url,
-                subscriptions,
-                new_subscription_recv,
-                on_drop_recv,
-                wallet,
-            )
-        } else {
-            Self::http_worker(
-                http_client,
-                subscriptions,
-                new_subscription_recv,
-                on_drop_recv,
-                wallet,
-            )
-        }
-    }
-
-    /// Subscribe to a WebSocket channel
-    pub async fn subscribe(
         &self,
-        filter: Params,
+        id: String,
-    ) -> (mpsc::Sender<SubId>, mpsc::Receiver<NotificationPayload>) {
+        params: NotificationId<String>,
-        let mut subscriptions = self.subscriptions.write().await;
+    ) -> Option<(usize, String)> {
-        let id = filter.id.clone();
+        let (kind, filter) = match params {
+            NotificationId::ProofState(x) => (Kind::ProofState, x.to_string()),
+            NotificationId::MeltQuoteBolt11(q) | NotificationId::MeltQuoteBolt12(q) => {
+                (Kind::Bolt11MeltQuote, q)
+            }
+            NotificationId::MintQuoteBolt11(q) => (Kind::Bolt11MintQuote, q),
+            NotificationId::MintQuoteBolt12(q) => (Kind::Bolt12MintQuote, q),
+        };
 
-        let (sender, receiver) = mpsc::channel(10_000);
+        let request: WsRequest<_> = (
-        subscriptions.insert(id.clone(), (sender, filter));
+            WsMethodRequest::Subscribe(WalletParams {
-        drop(subscriptions);
+                kind,
+                filters: vec![filter],
+                id: id.into(),
+            }),
+            self.req_id
+                .fetch_add(1, std::sync::atomic::Ordering::Relaxed),
+        )
+            .into();
 
-        let _ = self.new_subscription_notif.send(id).await;
+        serde_json::to_string(&request)
-        (self.on_drop_notif.clone(), receiver)
+            .inspect_err(|err| {
+                tracing::error!("Could not serialize subscribe message: {:?}", err);
+            })
+            .map(|json| (request.id, json))
+            .ok()
     }
 
-    /// HTTP subscription client
+    fn get_unsub_request(&self, sub_id: String) -> Option<String> {
-    ///
+        let request: WsRequest<_> = (
-    /// This is a poll based subscription, where the client will poll the server
+            WsMethodRequest::Unsubscribe(WsUnsubscribeRequest { sub_id }),
-    /// from time to time to get updates, notifying the subscribers on changes
+            self.req_id
-    fn http_worker(
+                .fetch_add(1, std::sync::atomic::Ordering::Relaxed),
-        http_client: Arc<dyn MintConnector + Send + Sync>,
+        )
-        subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
+            .into();
-        new_subscription_recv: mpsc::Receiver<SubId>,
-        on_drop: mpsc::Receiver<SubId>,
-        wallet: Arc<Wallet>,
-    ) -> Option<JoinHandle<()>> {
-        let http_worker = http::http_main(
-            vec![],
-            http_client,
-            subscriptions,
-            new_subscription_recv,
-            on_drop,
-            wallet,
-        );
 
-        #[cfg(target_arch = "wasm32")]
+        match serde_json::to_string(&request) {
-        {
+            Ok(json) => Some(json),
-            wasm_bindgen_futures::spawn_local(http_worker);
+            Err(err) => {
+                tracing::error!("Could not serialize unsubscribe message: {:?}", err);
                 None
             }
+        }
+    }
+}
 
+#[cfg_attr(target_arch = "wasm32", async_trait::async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait::async_trait)]
+impl Transport for SubscriptionClient {
+    type Spec = MintSubTopics;
+
+    fn new_name(&self) -> <Self::Spec as Spec>::SubscriptionId {
+        Uuid::new_v4().to_string()
+    }
+
+    async fn stream(
+        &self,
+        _ctrls: mpsc::Receiver<StreamCtrl<Self::Spec>>,
+        _topics: Vec<SubscribeMessage<Self::Spec>>,
+        _reply_to: InternalRelay<Self::Spec>,
+    ) -> Result<(), PubsubError> {
         #[cfg(not(target_arch = "wasm32"))]
+        let r = ws::stream_client(self, _ctrls, _topics, _reply_to).await;
+
+        #[cfg(target_arch = "wasm32")]
+        let r = Err(PubsubError::NotSupported);
+
+        r
+    }
+
+    /// Poll on demand
+    async fn poll(
+        &self,
+        topics: Vec<SubscribeMessage<Self::Spec>>,
+        reply_to: InternalRelay<Self::Spec>,
+    ) -> Result<(), PubsubError> {
+        let proofs = topics
+            .iter()
+            .filter_map(|(_, x)| match &x {
+                NotificationId::ProofState(p) => Some(*p),
+                _ => None,
+            })
+            .collect::<Vec<_>>();
+
+        if !proofs.is_empty() {
+            for state in self
+                .http_client
+                .post_check_state(CheckStateRequest { ys: proofs })
+                .await
+                .map_err(|e| PubsubError::Internal(Box::new(e)))?
+                .states
             {
-            Some(tokio::spawn(http_worker))
+                reply_to.send(MintEvent::new(NotificationPayload::ProofState(state)));
             }
         }
 
-    /// WebSocket subscription client
+        for topic in topics
-    ///
+            .into_iter()
-    /// This is a WebSocket based subscription, where the client will connect to
+            .map(|(_, x)| x)
-    /// the server and stay there idle waiting for server-side notifications
+            .filter(|x| !matches!(x, NotificationId::ProofState(_)))
-    #[cfg(all(
+        {
-        not(feature = "http_subscription"),
+            match topic {
-        feature = "mint",
+                NotificationId::MintQuoteBolt11(id) => {
-        not(target_arch = "wasm32")
+                    let response = match self.http_client.get_mint_quote_status(&id).await {
-    ))]
+                        Ok(success) => success,
-    fn ws_worker(
+                        Err(err) => {
-        http_client: Arc<dyn MintConnector + Send + Sync>,
+                            tracing::error!("Error with MintBolt11 {} with {:?}", id, err);
-        url: MintUrl,
+                            continue;
-        subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
+                        }
-        new_subscription_recv: mpsc::Receiver<SubId>,
+                    };
-        on_drop: mpsc::Receiver<SubId>,
+
-        wallet: Arc<Wallet>,
+                    reply_to.send(MintEvent::new(
-    ) -> Option<JoinHandle<()>> {
+                        NotificationPayload::MintQuoteBolt11Response(response.clone()),
-        Some(tokio::spawn(ws::ws_main(
+                    ));
-            http_client,
+                }
-            url,
+                NotificationId::MeltQuoteBolt11(id) => {
-            subscriptions,
+                    let response = match self.http_client.get_melt_quote_status(&id).await {
-            new_subscription_recv,
+                        Ok(success) => success,
-            on_drop,
+                        Err(err) => {
-            wallet,
+                            tracing::error!("Error with MeltBolt11 {} with {:?}", id, err);
-        )))
+                            continue;
+                        }
+                    };
+
+                    reply_to.send(MintEvent::new(
+                        NotificationPayload::MeltQuoteBolt11Response(response),
+                    ));
+                }
+                NotificationId::MintQuoteBolt12(id) => {
+                    let response = match self.http_client.get_mint_quote_bolt12_status(&id).await {
+                        Ok(success) => success,
+                        Err(err) => {
+                            tracing::error!("Error with MintBolt12 {} with {:?}", id, err);
+                            continue;
+                        }
+                    };
+
+                    reply_to.send(MintEvent::new(
+                        NotificationPayload::MintQuoteBolt12Response(response),
+                    ));
+                }
+                NotificationId::MeltQuoteBolt12(id) => {
+                    let response = match self.http_client.get_melt_bolt12_quote_status(&id).await {
+                        Ok(success) => success,
+                        Err(err) => {
+                            tracing::error!("Error with MeltBolt12 {} with {:?}", id, err);
+                            continue;
+                        }
+                    };
+
+                    reply_to.send(MintEvent::new(
+                        NotificationPayload::MeltQuoteBolt11Response(response),
+                    ));
+                }
+                _ => {}
             }
         }
 
-impl Drop for SubscriptionClient {
+        Ok(())
-    fn drop(&mut self) {
-        if let Some(handle) = self.worker.take() {
-            handle.abort();
-        }
     }
 }

crates/cdk/src/wallet/subscription/ws.rs

@@ -1,38 +1,25 @@
-use std::collections::{HashMap, HashSet};
+use cdk_common::nut17::ws::WsMessageOrResponse;
-use std::sync::atomic::AtomicUsize;
+use cdk_common::pub_sub::remote_consumer::{InternalRelay, StreamCtrl, SubscribeMessage};
-use std::sync::Arc;
+use cdk_common::pub_sub::Error as PubsubError;
-use std::time::Duration;
-
-use cdk_common::subscription::Params;
-use cdk_common::ws::{WsMessageOrResponse, WsMethodRequest, WsRequest, WsUnsubscribeRequest};
 #[cfg(feature = "auth")]
 use cdk_common::{Method, RoutePath};
 use futures::{SinkExt, StreamExt};
-use tokio::sync::{mpsc, RwLock};
+use tokio::sync::mpsc;
-use tokio::time::sleep;
 use tokio_tungstenite::connect_async;
 use tokio_tungstenite::tungstenite::client::IntoClientRequest;
 use tokio_tungstenite::tungstenite::Message;
 
-use super::http::http_main;
+use super::{MintSubTopics, SubscriptionClient};
-use super::WsSubscriptionBody;
-use crate::mint_url::MintUrl;
-use crate::pub_sub::SubId;
-use crate::wallet::MintConnector;
-use crate::Wallet;
 
-const MAX_ATTEMPT_FALLBACK_HTTP: usize = 10;
+#[inline(always)]
-
+pub(crate) async fn stream_client(
-#[inline]
+    client: &SubscriptionClient,
-pub async fn ws_main(
+    mut ctrl: mpsc::Receiver<StreamCtrl<MintSubTopics>>,
-    http_client: Arc<dyn MintConnector + Send + Sync>,
+    topics: Vec<SubscribeMessage<MintSubTopics>>,
-    mint_url: MintUrl,
+    reply_to: InternalRelay<MintSubTopics>,
-    subscriptions: Arc<RwLock<HashMap<SubId, WsSubscriptionBody>>>,
+) -> Result<(), PubsubError> {
-    mut new_subscription_recv: mpsc::Receiver<SubId>,
+    let mut url = client
-    mut on_drop: mpsc::Receiver<SubId>,
+        .mint_url
-    wallet: Arc<Wallet>,
-) {
-    let mut url = mint_url
         .join_paths(&["v1", "ws"])
         .expect("Could not join paths");
 
@@ -42,37 +29,23 @@ pub async fn ws_main(
         url.set_scheme("ws").expect("Could not set scheme");
     }
 
-    let request = match url.to_string().into_client_request() {
+    #[cfg(not(feature = "auth"))]
-        Ok(req) => req,
+    let request = url.to_string().into_client_request().map_err(|err| {
-        Err(err) => {
         tracing::error!("Failed to create client request: {:?}", err);
         // Fallback to HTTP client if we can't create the WebSocket request
-            return http_main(
+        cdk_common::pub_sub::Error::NotSupported
-                std::iter::empty(),
+    })?;
-                http_client,
-                subscriptions,
-                new_subscription_recv,
-                on_drop,
-                wallet,
-            )
-            .await;
-        }
-    };
 
-    let mut active_subscriptions = HashMap::<SubId, mpsc::Sender<_>>::new();
+    #[cfg(feature = "auth")]
-    let mut failure_count = 0;
+    let mut request = url.to_string().into_client_request().map_err(|err| {
+        tracing::error!("Failed to create client request: {:?}", err);
+        // Fallback to HTTP client if we can't create the WebSocket request
+        cdk_common::pub_sub::Error::NotSupported
+    })?;
 
-    loop {
-        if subscriptions.read().await.is_empty() {
-            // No active subscription
-            sleep(Duration::from_millis(100)).await;
-            continue;
-        }
-
-        let mut request_clone = request.clone();
     #[cfg(feature = "auth")]
     {
-            let auth_wallet = http_client.get_auth_wallet().await;
+        let auth_wallet = client.http_client.get_auth_wallet().await;
         let token = match auth_wallet.as_ref() {
             Some(auth_wallet) => {
                 let endpoint = cdk_common::ProtectedEndpoint::new(Method::Get, RoutePath::Ws);
@@ -95,7 +68,7 @@ pub async fn ws_main(
 
             match auth_token.to_string().parse() {
                 Ok(header_value) => {
-                        request_clone.headers_mut().insert(header_key, header_value);
+                    request.headers_mut().insert(header_key, header_value);
                 }
                 Err(err) => {
                     tracing::warn!("Failed to parse auth token as header value: {:?}", err);
@@ -105,83 +78,56 @@ pub async fn ws_main(
     }
 
     tracing::debug!("Connecting to {}", url);
-        let ws_stream = match connect_async(request_clone.clone()).await {
+    let ws_stream = connect_async(request)
-            Ok((ws_stream, _)) => ws_stream,
+        .await
-            Err(err) => {
+        .map(|(ws_stream, _)| ws_stream)
-                failure_count += 1;
+        .map_err(|err| {
-                tracing::error!("Could not connect to server: {:?}", err);
+            tracing::error!("Error connecting: {err:?}");
-                if failure_count > MAX_ATTEMPT_FALLBACK_HTTP {
+
-                    tracing::error!(
+            cdk_common::pub_sub::Error::Internal(Box::new(err))
-                        "Could not connect to server after {MAX_ATTEMPT_FALLBACK_HTTP} attempts, falling back to HTTP-subscription client"
+        })?;
-                    );
 
-                    return http_main(
-                        active_subscriptions.into_keys(),
-                        http_client,
-                        subscriptions,
-                        new_subscription_recv,
-                        on_drop,
-                        wallet,
-                    )
-                    .await;
-                }
-                continue;
-            }
-        };
     tracing::debug!("Connected to {}", url);
-
     let (mut write, mut read) = ws_stream.split();
-        let req_id = AtomicUsize::new(0);
 
-        let get_sub_request = |params: Params| -> Option<(usize, String)> {
+    for (name, index) in topics {
-            let request: WsRequest = (
+        let (_, req) = if let Some(req) = client.get_sub_request(name, index) {
-                WsMethodRequest::Subscribe(params),
+            req
-                req_id.fetch_add(1, std::sync::atomic::Ordering::Relaxed),
+        } else {
-            )
+            continue;
-                .into();
-
-            match serde_json::to_string(&request) {
-                Ok(json) => Some((request.id, json)),
-                Err(err) => {
-                    tracing::error!("Could not serialize subscribe message: {:?}", err);
-                    None
-                }
-            }
         };
 
-        let get_unsub_request = |sub_id: SubId| -> Option<String> {
-            let request: WsRequest = (
-                WsMethodRequest::Unsubscribe(WsUnsubscribeRequest { sub_id }),
-                req_id.fetch_add(1, std::sync::atomic::Ordering::Relaxed),
-            )
-                .into();
-
-            match serde_json::to_string(&request) {
-                Ok(json) => Some(json),
-                Err(err) => {
-                    tracing::error!("Could not serialize unsubscribe message: {:?}", err);
-                    None
-                }
-            }
-        };
-
-        // Websocket reconnected, restore all subscriptions
-        let mut subscription_requests = HashSet::new();
-
-        let read_subscriptions = subscriptions.read().await;
-        for (sub_id, _) in active_subscriptions.iter() {
-            if let Some(Some((req_id, req))) = read_subscriptions
-                .get(sub_id)
-                .map(|(_, params)| get_sub_request(params.clone()))
-            {
         let _ = write.send(Message::Text(req.into())).await;
-                subscription_requests.insert(req_id);
     }
-        }
-        drop(read_subscriptions);
 
     loop {
         tokio::select! {
+            Some(msg) = ctrl.recv() => {
+                match msg {
+                    StreamCtrl::Subscribe(msg) => {
+                        let (_, req) = if let Some(req) = client.get_sub_request(msg.0, msg.1) {
+                            req
+                        } else {
+                            continue;
+                        };
+                        let _ = write.send(Message::Text(req.into())).await;
+                    }
+                    StreamCtrl::Unsubscribe(msg) => {
+                        let req = if let Some(req) = client.get_unsub_request(msg) {
+                            req
+                        } else {
+                            continue;
+                        };
+                        let _ = write.send(Message::Text(req.into())).await;
+                    }
+                    StreamCtrl::Stop => {
+                        if let Err(err) = write.send(Message::Close(None)).await {
+                            tracing::error!("Closing error {err:?}");
+                        }
+                        break;
+                    }
+                };
+            }
             Some(msg) = read.next() => {
                 let msg = match msg {
                     Ok(msg) => msg,
@@ -189,94 +135,34 @@ pub async fn ws_main(
                         if let Err(err) = write.send(Message::Close(None)).await {
                             tracing::error!("Closing error {err:?}");
                         }
-                            break
+                        break;
-                        },
+                    }
                 };
                 let msg = match msg {
                     Message::Text(msg) => msg,
                     _ => continue,
                 };
-                    let msg = match serde_json::from_str::<WsMessageOrResponse>(&msg) {
+                let msg = match serde_json::from_str::<WsMessageOrResponse<String>>(&msg) {
                     Ok(msg) => msg,
                     Err(_) => continue,
                 };
 
                 match msg {
                     WsMessageOrResponse::Notification(payload) => {
-                            tracing::debug!("Received notification from server: {:?}", payload);
+                        reply_to.send(payload.params.payload);
-                            let _ = active_subscriptions.get(&payload.params.sub_id).map(|sender| {
-                                let _ = sender.try_send(payload.params.payload);
-                            });
                     }
                     WsMessageOrResponse::Response(response) => {
                         tracing::debug!("Received response from server: {:?}", response);
-                            subscription_requests.remove(&response.id);
-                            // reset connection failure after a successful response from the serer
-                            failure_count = 0;
                     }
                     WsMessageOrResponse::ErrorResponse(error) => {
-                            tracing::error!("Received error from server: {:?}", error);
+                        tracing::debug!("Received an error from server: {:?}", error);
-
+                        return Err(PubsubError::InternalStr(error.error.message));
-                            if subscription_requests.contains(&error.id) {
-                                failure_count += 1;
-                                if failure_count > MAX_ATTEMPT_FALLBACK_HTTP {
-                                    tracing::error!(
-                                        "Falling back to HTTP client"
-                                    );
-
-                                    return http_main(
-                                        active_subscriptions.into_keys(),
-                                        http_client,
-                                        subscriptions,
-                                        new_subscription_recv,
-                                        on_drop,
-                                        wallet,
-                                    )
-                                    .await;
-                                }
-
-                                if let Err(err) = write.send(Message::Close(None)).await {
-                                    tracing::error!("Closing error {err:?}");
-                                }
-
-                                break; // break connection to force a reconnection, to attempt to recover form this error
-                            }
                     }
                 }
 
             }
-                Some(subid) = new_subscription_recv.recv() => {
-                    let subscription = subscriptions.read().await;
-                    let sub = if let Some(subscription) = subscription.get(&subid) {
-                        subscription
-                    } else {
-                        continue
-                    };
-                    tracing::debug!("Subscribing to {:?}", sub.1);
-                    active_subscriptions.insert(subid, sub.0.clone());
-                    if let Some((req_id, json)) = get_sub_request(sub.1.clone()) {
-                        let _ = write.send(Message::Text(json.into())).await;
-                        subscription_requests.insert(req_id);
         }
-                },
-                Some(subid) = on_drop.recv() => {
-                    let mut subscription = subscriptions.write().await;
-                    if let Some(sub) = subscription.remove(&subid) {
-                        drop(sub);
-                    }
-                    tracing::debug!("Unsubscribing from {:?}", subid);
-                    if let Some(json) = get_unsub_request(subid) {
-                        let _ = write.send(Message::Text(json.into())).await;
     }
 
-                    if subscription.is_empty() {
+    Ok(())
-                        if let Err(err) = write.send(Message::Close(None)).await {
-                            tracing::error!("Closing error {err:?}");
-                        }
-                        break;
-                    }
-                }
-            }
-        }
-    }
 }

justfile

@@ -66,14 +66,14 @@ test:
 
   
 # run doc tests
-test-pure db="memory": build
+test-pure db="memory":
   #!/usr/bin/env bash
   set -euo pipefail
   if [ ! -f Cargo.toml ]; then
     cd {{invocation_directory()}}
   fi
 
-  # Run pure integration tests
+  # Run pure integration tests (cargo test will only build what's needed for the test)
   CDK_TEST_DB_TYPE={{db}} cargo test -p cdk-integration-tests --test integration_tests_pure -- --test-threads 1
 
 test-all db="memory":