Struct MessageDispatcher

pub struct MessageDispatcher<R> { /* private fields */ }

Provides a dispatcher for sending MCP messages and handling responses.

MessageDispatcher facilitates MCP communication by managing message sending, request tracking, and response handling. It supports both client-to-server and server-to-client message flows through implementations of the McpDispatch trait. The dispatcher uses a transport mechanism (e.g., stdin/stdout) to serialize and send messages, and it tracks pending requests with a configurable timeout mechanism for asynchronous responses.

Implementations

impl<R> MessageDispatcher<R>

pub fn new( pending_requests: Arc<Mutex<HashMap<RequestId, Sender<R>>>>, writable_std: Mutex<Pin<Box<dyn AsyncWrite + Send + Sync>>>, message_id_counter: Arc<AtomicI64>, request_timeout: Duration, ) -> MessageDispatcher<R>

Creates a new MessageDispatcher instance with the given configuration.

Arguments

• pending_requests - A thread-safe map for storing pending request IDs and their response channels.
• writable_std - A mutex-protected, pinned writer (e.g., stdout) for sending serialized messages.
• message_id_counter - An atomic counter for generating unique request IDs.
• request_timeout - The timeout duration in milliseconds for awaiting responses.

Returns

A new MessageDispatcher instance configured for MCP message handling.

Trait Implementations

impl McpDispatch<ClientMessage, MessageFromServer> for MessageDispatcher<ClientMessage>

fn send<'life0, 'async_trait>( &'life0 self, message: MessageFromServer, request_id: Option<RequestId>, request_timeout: Option<Duration>, ) -> Pin<Box<dyn Future<Output = Result<Option<ClientMessage>, TransportError>> + Send + 'async_trait>>

where 'life0: 'async_trait, MessageDispatcher<ClientMessage>: 'async_trait,

Sends a message from the server to the client and awaits a response if applicable.

Serializes the MessageFromServer to JSON, writes it to the transport, and waits for a ClientMessage response if the message is a request. Notifications and responses return Ok(None).

Arguments

• message - The server message to send.
• request_id - An optional request ID (used for responses/errors, None for requests).

Returns

A TransportResult containing Some(ClientMessage) for requests with a response, or None for notifications/responses, or an error if the operation fails.

Errors

Returns a TransportError if serialization, writing, or timeout occurs.

impl McpDispatch<ServerMessage, MessageFromClient> for MessageDispatcher<ServerMessage>

fn send<'life0, 'async_trait>( &'life0 self, message: MessageFromClient, request_id: Option<RequestId>, request_timeout: Option<Duration>, ) -> Pin<Box<dyn Future<Output = Result<Option<ServerMessage>, TransportError>> + Send + 'async_trait>>

where 'life0: 'async_trait, MessageDispatcher<ServerMessage>: 'async_trait,

Sends a message from the client to the server and awaits a response if applicable.

Serializes the MessageFromClient to JSON, writes it to the transport, and waits for a ServerMessage response if the message is a request. Notifications and responses return Ok(None).

Arguments

• message - The client message to send.
• request_id - An optional request ID (used for responses/errors, None for requests).

Returns

A TransportResult containing Some(ServerMessage) for requests with a response, or None for notifications/responses, or an error if the operation fails.

Errors

Returns a TransportError if serialization, writing, or timeout occurs.