refactor: provide http server as tower service (#228)

* refactor: streamable http server as tower service

Author: 4t145

crates/rmcp/Cargo.toml

@@ -39,7 +39,9 @@ reqwest = { version = "0.12", default-features = false, features = [
     "json",
     "stream",
 ], optional = true }
-sse-stream = { version = "0.2.0", optional = true }
+
+sse-stream = { version = "0.2", optional = true }
+
 http = { version = "1", optional = true }
 url = { version = "2.4", optional = true }
 
@@ -57,7 +59,9 @@ axum = { version = "0.8", features = [], optional = true }
 rand = { version = "0.9", optional = true }
 tokio-stream = { version = "0.1", optional = true }
 uuid = { version = "1", features = ["v4"], optional = true }
-
+http-body = { version = "1", optional = true }
+http-body-util = { version = "0.1", optional = true }
+bytes = { version = "1", optional = true }
 # macro
 rmcp-macros = { version = "0.1", workspace = true, optional = true }
 
@@ -74,7 +78,17 @@ reqwest = ["__reqwest", "reqwest?/rustls-tls"]
 
 reqwest-tls-no-provider = ["__reqwest", "reqwest?/rustls-tls-no-provider"]
 
-axum = ["dep:axum"]
+server-side-http = [
+    "uuid",
+    "dep:rand",
+    "dep:tokio-stream",
+    "dep:http",
+    "dep:http-body",
+    "dep:http-body-util",
+    "dep:bytes",
+    "dep:sse-stream",
+    "tower",
+]
 # SSE client
 client-side-sse = ["dep:sse-stream", "dep:http"]
 
@@ -97,15 +111,12 @@ transport-child-process = [
 transport-sse-server = [
     "transport-async-rw",
     "transport-worker",
-    "axum",
-    "dep:rand",
-    "dep:tokio-stream",
-    "uuid",
+    "server-side-http",
+    "dep:axum",
 ]
 transport-streamable-http-server = [
     "transport-streamable-http-server-session",
-    "axum",
-    "uuid",
+    "server-side-http",
 ]
 transport-streamable-http-server-session = [
     "transport-async-rw",

crates/rmcp/src/service.rs

@@ -488,7 +488,7 @@ pub struct RequestContext<R: ServiceRole> {
 }
 
 /// Use this function to skip initialization process
-pub async fn serve_directly<R, S, T, E, A>(
+pub fn serve_directly<R, S, T, E, A>(
     service: S,
     transport: T,
     peer_info: Option<R::PeerInfo>,
@@ -499,11 +499,11 @@ where
     T: IntoTransport<R, E, A>,
     E: std::error::Error + Send + Sync + 'static,
 {
-    serve_directly_with_ct(service, transport, peer_info, Default::default()).await
+    serve_directly_with_ct(service, transport, peer_info, Default::default())
 }
 
 /// Use this function to skip initialization process
-pub async fn serve_directly_with_ct<R, S, T, E, A>(
+pub fn serve_directly_with_ct<R, S, T, E, A>(
     service: S,
     transport: T,
     peer_info: Option<R::PeerInfo>,
@@ -516,11 +516,11 @@ where
     E: std::error::Error + Send + Sync + 'static,
 {
     let (peer, peer_rx) = Peer::new(Arc::new(AtomicU32RequestIdProvider::default()), peer_info);
-    serve_inner(service, transport, peer, peer_rx, ct).await
+    serve_inner(service, transport, peer, peer_rx, ct)
 }
 
 #[instrument(skip_all)]
-async fn serve_inner<R, S, T, E, A>(
+fn serve_inner<R, S, T, E, A>(
     service: S,
     transport: T,
     peer: Peer<R>,

crates/rmcp/src/service/client.rs

@@ -111,7 +111,7 @@ pub async fn serve_client<S, T, E, A>(
 where
     S: Service<RoleClient>,
     T: IntoTransport<RoleClient, E, A>,
-    E: std::error::Error + From<std::io::Error> + Send + Sync + 'static,
+    E: std::error::Error + Send + Sync + 'static,
 {
     serve_client_with_ct(service, transport, Default::default()).await
 }
@@ -124,7 +124,7 @@ pub async fn serve_client_with_ct<S, T, E, A>(
 where
     S: Service<RoleClient>,
     T: IntoTransport<RoleClient, E, A>,
-    E: std::error::Error + From<std::io::Error> + Send + Sync + 'static,
+    E: std::error::Error + Send + Sync + 'static,
 {
     let mut transport = transport.into_transport();
     let id_provider = <Arc<AtomicU32RequestIdProvider>>::default();
@@ -175,7 +175,7 @@ where
             context: "send initialized notification".into(),
         })?;
     let (peer, peer_rx) = Peer::new(id_provider, Some(initialize_result));
-    Ok(serve_inner(service, transport, peer, peer_rx, ct).await)
+    Ok(serve_inner(service, transport, peer, peer_rx, ct))
 }
 
 macro_rules! method {

crates/rmcp/src/service/server.rs

@@ -70,7 +70,7 @@ impl<S: Service<RoleServer>> ServiceExt<RoleServer> for S {
     ) -> impl Future<Output = Result<RunningService<RoleServer, Self>, ServerInitializeError<E>>> + Send
     where
         T: IntoTransport<RoleServer, E, A>,
-        E: std::error::Error + From<std::io::Error> + Send + Sync + 'static,
+        E: std::error::Error + Send + Sync + 'static,
         Self: Sized,
     {
         serve_server_with_ct(self, transport, ct)
@@ -84,7 +84,7 @@ pub async fn serve_server<S, T, E, A>(
 where
     S: Service<RoleServer>,
     T: IntoTransport<RoleServer, E, A>,
-    E: std::error::Error + From<std::io::Error> + Send + Sync + 'static,
+    E: std::error::Error + Send + Sync + 'static,
 {
     serve_server_with_ct(service, transport, CancellationToken::new()).await
 }
@@ -143,7 +143,7 @@ pub async fn serve_server_with_ct<S, T, E, A>(
 where
     S: Service<RoleServer>,
     T: IntoTransport<RoleServer, E, A>,
-    E: std::error::Error + From<std::io::Error> + Send + Sync + 'static,
+    E: std::error::Error + Send + Sync + 'static,
 {
     let mut transport = transport.into_transport();
     let id_provider = <Arc<AtomicU32RequestIdProvider>>::default();
@@ -212,7 +212,7 @@ where
     };
     let _ = service.handle_notification(notification).await;
     // Continue processing service
-    Ok(serve_inner(service, transport, peer, peer_rx, ct).await)
+    Ok(serve_inner(service, transport, peer, peer_rx, ct))
 }
 
 macro_rules! method {

crates/rmcp/src/transport.rs

@@ -7,7 +7,7 @@
 //! | transport         | client                                                    | server                                                |
 //! |:-:                |:-:                                                        |:-:                                                    |
 //! | std IO            | [`child_process::TokioChildProcess`]                      | [`io::stdio`]                                         |
-//! | streamable http   | [`streamable_http_client::StreamableHttpClientTransport`] | [`streamable_http_server::session::create_session`]   |
+//! | streamable http   | [`streamable_http_client::StreamableHttpClientTransport`] | [`streamable_http_server::StreamableHttpService`]     |
 //! | sse               | [`sse_client::SseClientTransport`]                        | [`sse_server::SseServer`]                             |
 //!
 //！## Helper Transport Types
@@ -64,6 +64,8 @@
 //! }
 //! ```
 
+use std::sync::Arc;
+
 use crate::service::{RxJsonRpcMessage, ServiceRole, TxJsonRpcMessage};
 
 pub mod sink_stream;
@@ -122,7 +124,7 @@ pub use auth::{AuthError, AuthorizationManager, AuthorizationSession, Authorized
 pub mod streamable_http_server;
 #[cfg(feature = "transport-streamable-http-server")]
 #[cfg_attr(docsrs, doc(cfg(feature = "transport-streamable-http-server")))]
-pub use streamable_http_server::axum::StreamableHttpServer;
+pub use streamable_http_server::tower::{StreamableHttpServerConfig, StreamableHttpService};
 
 #[cfg(feature = "transport-streamable-http-client")]
 #[cfg_attr(docsrs, doc(cfg(feature = "transport-streamable-http-client")))]
@@ -138,7 +140,7 @@ pub trait Transport<R>: Send
 where
     R: ServiceRole,
 {
-    type Error;
+    type Error: std::error::Error + Send + Sync + 'static;
     /// Send a message to the transport
     ///
     /// Notice that the future returned by this function should be `Send` and `'static`.
@@ -169,9 +171,73 @@ impl<R, T, E> IntoTransport<R, E, TransportAdapterIdentity> for T
 where
     T: Transport<R, Error = E> + Send + 'static,
     R: ServiceRole,
-    E: std::error::Error + Send + 'static,
+    E: std::error::Error + Send + Sync + 'static,
 {
     fn into_transport(self) -> impl Transport<R, Error = E> + 'static {
         self
     }
 }
+
+/// A transport that can send a single message and then close itself
+pub struct OneshotTransport<R>
+where
+    R: ServiceRole,
+{
+    message: Option<RxJsonRpcMessage<R>>,
+    sender: tokio::sync::mpsc::Sender<TxJsonRpcMessage<R>>,
+    finished_signal: Arc<tokio::sync::Notify>,
+}
+
+impl<R> OneshotTransport<R>
+where
+    R: ServiceRole,
+{
+    pub fn new(
+        message: RxJsonRpcMessage<R>,
+    ) -> (Self, tokio::sync::mpsc::Receiver<TxJsonRpcMessage<R>>) {
+        let (sender, receiver) = tokio::sync::mpsc::channel(16);
+        (
+            Self {
+                message: Some(message),
+                sender,
+                finished_signal: Arc::new(tokio::sync::Notify::new()),
+            },
+            receiver,
+        )
+    }
+}
+
+impl<R> Transport<R> for OneshotTransport<R>
+where
+    R: ServiceRole,
+{
+    type Error = tokio::sync::mpsc::error::SendError<TxJsonRpcMessage<R>>;
+
+    fn send(
+        &mut self,
+        item: TxJsonRpcMessage<R>,
+    ) -> impl Future<Output = Result<(), Self::Error>> + Send + 'static {
+        let sender = self.sender.clone();
+        let terminate = matches!(item, TxJsonRpcMessage::<R>::Response(_));
+        let signal = self.finished_signal.clone();
+        async move {
+            sender.send(item).await?;
+            if terminate {
+                signal.notify_waiters();
+            }
+            Ok(())
+        }
+    }
+
+    async fn receive(&mut self) -> Option<RxJsonRpcMessage<R>> {
+        if self.message.is_none() {
+            self.finished_signal.notified().await;
+        }
+        self.message.take()
+    }
+
+    fn close(&mut self) -> impl Future<Output = Result<(), Self::Error>> + Send {
+        self.message.take();
+        std::future::ready(Ok(()))
+    }
+}

crates/rmcp/src/transport/common.rs

@@ -2,7 +2,7 @@
     feature = "transport-streamable-http-server",
     feature = "transport-sse-server"
 ))]
-pub mod axum;
+pub mod server_side_http;
 
 pub mod http_header;