Revert "Add message queue for SSE messages POST endpoint (#459)" (#649)

src/mcp/server/fastmcp/server.py

@@ -44,7 +44,6 @@ from mcp.server.lowlevel.helper_types import ReadResourceContents
 from mcp.server.lowlevel.server import LifespanResultT
 from mcp.server.lowlevel.server import Server as MCPServer
 from mcp.server.lowlevel.server import lifespan as default_lifespan
-from mcp.server.message_queue import MessageDispatch
 from mcp.server.session import ServerSession, ServerSessionT
 from mcp.server.sse import SseServerTransport
 from mcp.server.stdio import stdio_server
@@ -92,11 +91,6 @@ class Settings(BaseSettings, Generic[LifespanResultT]):
     sse_path: str = "/sse"
     message_path: str = "/messages/"
 
-    # SSE message queue settings
-    message_dispatch: MessageDispatch | None = Field(
-        None, description="Custom message dispatch instance"
-    )
-
     # resource settings
     warn_on_duplicate_resources: bool = True
 
@@ -607,13 +601,6 @@ class FastMCP:
 
     def sse_app(self, mount_path: str | None = None) -> Starlette:
         """Return an instance of the SSE server app."""
-        message_dispatch = self.settings.message_dispatch
-        if message_dispatch is None:
-            from mcp.server.message_queue import InMemoryMessageDispatch
-
-            message_dispatch = InMemoryMessageDispatch()
-            logger.info("Using default in-memory message dispatch")
-
         from starlette.middleware import Middleware
         from starlette.routing import Mount, Route
 
@@ -625,12 +612,11 @@ class FastMCP:
         normalized_message_endpoint = self._normalize_path(
             self.settings.mount_path, self.settings.message_path
         )
-        
+
         # Set up auth context and dependencies
 
         sse = SseServerTransport(
-          normalized_message_endpoint,
-          message_dispatch=message_dispatch
+            normalized_message_endpoint,
         )
 
         async def handle_sse(scope: Scope, receive: Receive, send: Send):
@@ -646,14 +632,7 @@ class FastMCP:
                     streams[1],
                     self._mcp_server.create_initialization_options(),
                 )
-                return Response()
-
-        @asynccontextmanager
-        async def lifespan(app: Starlette):
-            try:
-                yield
-            finally:
-                await message_dispatch.close()
+            return Response()
 
         # Create routes
         routes: list[Route | Mount] = []
@@ -730,10 +709,7 @@ class FastMCP:
 
         # Create Starlette app with routes and middleware
         return Starlette(
-            debug=self.settings.debug,
-            routes=routes,
-            middleware=middleware,
-            lifespan=lifespan,
+            debug=self.settings.debug, routes=routes, middleware=middleware
         )
 
     async def list_prompts(self) -> list[MCPPrompt]: