diff --git a/bindings/javascript/sync/src/js_protocol_io.rs b/bindings/javascript/sync/src/js_protocol_io.rs
index 9208e4636..bbe68b66d 100644
--- a/bindings/javascript/sync/src/js_protocol_io.rs
+++ b/bindings/javascript/sync/src/js_protocol_io.rs
@@ -241,6 +241,10 @@ impl ProtocolIO for JsProtocolIo {
                 .collect(),
         }))
     }
+
+    fn register(&self, callback: Box<dyn FnMut() -> bool>) {
+        tracing::info!("register callback in the ProtocolIo");
+    }
 }
 
 #[napi]
diff --git a/bindings/javascript/sync/src/lib.rs b/bindings/javascript/sync/src/lib.rs
index f2e5b0e23..64be75f1a 100644
--- a/bindings/javascript/sync/src/lib.rs
+++ b/bindings/javascript/sync/src/lib.rs
@@ -119,6 +119,7 @@ pub struct SyncEngineOpts {
     pub protocol_version: Option<SyncEngineProtocolVersion>,
     pub bootstrap_if_empty: bool,
     pub remote_encryption: Option<String>,
+    pub partial: Option<bool>,
 }
 
 struct SyncEngineOptsFilled {
@@ -131,6 +132,7 @@ struct SyncEngineOptsFilled {
     pub protocol_version: DatabaseSyncEngineProtocolVersion,
     pub bootstrap_if_empty: bool,
     pub remote_encryption: Option<CipherMode>,
+    pub partial: bool,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -224,6 +226,7 @@ impl SyncEngine {
                     ))
                 }
             },
+            partial: opts.partial.unwrap_or(false),
         };
         Ok(SyncEngine {
             opts: opts_filled,
@@ -251,6 +254,7 @@ impl SyncEngine {
                 .remote_encryption
                 .map(|x| x.required_metadata_size())
                 .unwrap_or(0),
+            partial: self.opts.partial,
         };
 
         let io = self.io()?;
diff --git a/sync/engine/src/protocol_io.rs b/sync/engine/src/protocol_io.rs
index 19933b993..369b82112 100644
--- a/sync/engine/src/protocol_io.rs
+++ b/sync/engine/src/protocol_io.rs
@@ -12,7 +12,6 @@ pub trait DataCompletion<T> {
     fn status(&self) -> Result<Option<u16>>;
     fn poll_data(&self) -> Result<Option<Self::DataPollResult>>;
     fn is_done(&self) -> Result<bool>;
-    fn set_callback(&self, callback: Box<dyn FnMut() -> ()>);
 }
 
 pub trait ProtocolIO: Send + Sync + 'static {