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

Author: ihrpr

README.md

@@ -449,30 +449,6 @@ if __name__ == "__main__":
 
 For more information on mounting applications in Starlette, see the [Starlette documentation](https://www.starlette.io/routing/#submounting-routes).
 
-#### Message Dispatch Options
-
-By default, the SSE server uses an in-memory message dispatch system for incoming POST messages. For production deployments or distributed scenarios, you can use Redis or implement your own message dispatch system that conforms to the `MessageDispatch` protocol:
-
-```python
-# Using the built-in Redis message dispatch
-from mcp.server.fastmcp import FastMCP
-from mcp.server.message_queue import RedisMessageDispatch
-
-# Create a Redis message dispatch
-redis_dispatch = RedisMessageDispatch(
-    redis_url="redis://localhost:6379/0", prefix="mcp:pubsub:"
-)
-
-# Pass the message dispatch instance to the server
-mcp = FastMCP("My App", message_queue=redis_dispatch)
-```
-
-To use Redis, add the Redis dependency:
-
-```bash
-uv add "mcp[redis]"
-```
-
 ## Examples
 
 ### Echo Server

examples/servers/simple-prompt/mcp_simple_prompt/server.py

@@ -88,15 +88,12 @@ async def get_prompt(
         )
 
     if transport == "sse":
-        from mcp.server.message_queue.redis import RedisMessageDispatch
         from mcp.server.sse import SseServerTransport
         from starlette.applications import Starlette
         from starlette.responses import Response
         from starlette.routing import Mount, Route
 
-        message_dispatch = RedisMessageDispatch("redis://localhost:6379/0")
-
-        sse = SseServerTransport("/messages/", message_dispatch=message_dispatch)
+        sse = SseServerTransport("/messages/")
 
         async def handle_sse(request):
             async with sse.connect_sse(

pyproject.toml

@@ -37,7 +37,6 @@ dependencies = [
 rich = ["rich>=13.9.4"]
 cli = ["typer>=0.12.4", "python-dotenv>=1.0.0"]
 ws = ["websockets>=15.0.1"]
-redis = ["redis>=5.2.1", "types-redis>=4.6.0.20241004"]
 
 [project.scripts]
 mcp = "mcp.cli:app [cli]"
@@ -56,7 +55,6 @@ dev = [
     "pytest-xdist>=3.6.1",
     "pytest-examples>=0.0.14",
     "pytest-pretty>=1.2.0",
-    "fakeredis==2.28.1",
 ]
 docs = [
     "mkdocs>=1.6.1",

src/mcp/client/sse.py

@@ -98,9 +98,7 @@ async def sse_reader(
                                             await read_stream_writer.send(exc)
                                             continue
 
-                                        session_message = SessionMessage(
-                                            message=message
-                                        )
+                                        session_message = SessionMessage(message)
                                         await read_stream_writer.send(session_message)
                                     case _:
                                         logger.warning(
@@ -150,5 +148,3 @@ async def post_writer(endpoint_url: str):
         finally:
             await read_stream_writer.aclose()
             await write_stream.aclose()
-            await read_stream.aclose()
-            await write_stream_reader.aclose()

src/mcp/client/stdio/__init__.py

@@ -144,7 +144,7 @@ async def stdout_reader():
                             await read_stream_writer.send(exc)
                             continue
 
-                        session_message = SessionMessage(message=message)
+                        session_message = SessionMessage(message)
                         await read_stream_writer.send(session_message)
         except anyio.ClosedResourceError:
             await anyio.lowlevel.checkpoint()

src/mcp/client/streamable_http.py

@@ -153,7 +153,7 @@ async def _handle_sse_event(
                 ):
                     message.root.id = original_request_id
 
-                session_message = SessionMessage(message=message)
+                session_message = SessionMessage(message)
                 await read_stream_writer.send(session_message)
 
                 # Call resumption token callback if we have an ID
@@ -286,7 +286,7 @@ async def _handle_json_response(
         try:
             content = await response.aread()
             message = JSONRPCMessage.model_validate_json(content)
-            session_message = SessionMessage(message=message)
+            session_message = SessionMessage(message)
             await read_stream_writer.send(session_message)
         except Exception as exc:
             logger.error(f"Error parsing JSON response: {exc}")
@@ -333,7 +333,7 @@ async def _send_session_terminated_error(
             id=request_id,
             error=ErrorData(code=32600, message="Session terminated"),
         )
-        session_message = SessionMessage(message=JSONRPCMessage(jsonrpc_error))
+        session_message = SessionMessage(JSONRPCMessage(jsonrpc_error))
         await read_stream_writer.send(session_message)
 
     async def post_writer(

src/mcp/client/websocket.py

@@ -60,7 +60,7 @@ async def ws_reader():
                 async for raw_text in ws:
                     try:
                         message = types.JSONRPCMessage.model_validate_json(raw_text)
-                        session_message = SessionMessage(message=message)
+                        session_message = SessionMessage(message)
                         await read_stream_writer.send(session_message)
                     except ValidationError as exc:
                         # If JSON parse or model validation fails, send the exception

src/mcp/server/fastmcp/server.py

@@ -44,7 +44,6 @@
 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 @@ def _normalize_path(self, mount_path: str, endpoint: str) -> str:
 
     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 @@ def sse_app(self, mount_path: str | None = None) -> Starlette:
         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 @@ async def handle_sse(scope: Scope, receive: Receive, send: Send):
                     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 @@ async def sse_endpoint(request: Request) -> None:
 
         # 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]: