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introduce onsessioninitialized to avoid race conditions

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ihrpr 2025-04-16 11:09:47 +01:00
commit 585dc06708
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1 changed files with 45 additions and 46 deletions
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23
src/server/streamableHttp.ts
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@ -1,6 +1,6 @@
import { IncomingMessage, ServerResponse } from "node:http";
import { Transport } from "../shared/transport.js";
import { isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema, RequestId } from "../types.js";
import { isInitializeRequest, isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema, RequestId } from "../types.js";
import getRawBody from "raw-body";
import contentType from "content-type";
import { randomUUID } from "node:crypto";
@ -39,6 +39,15 @@ export interface StreamableHTTPServerTransportOptions {
*/
sessionIdGenerator: () => string | undefined;
/**
* A callback for session initialization events
* This is called when the server initializes a new session.
* Usefult in cases when you need to register multiple mcp sessions
* and need to keep track of them.
* @param sessionId The generated session ID
*/
onsessioninitialized?: (sessionId: string) => void;
/**
* If true, the server will return JSON responses instead of starting an SSE stream.
* This can be useful for simple request/response scenarios without streaming.
@ -98,6 +107,7 @@ export class StreamableHTTPServerTransport implements Transport {
private _enableJsonResponse: boolean = false;
private _standaloneSseStreamId: string = '_GET_stream';
private _eventStore?: EventStore;
private _onsessioninitialized?: (sessionId: string) => void;
sessionId?: string | undefined;
onclose?: () => void;
@ -108,6 +118,7 @@ export class StreamableHTTPServerTransport implements Transport {
this.sessionIdGenerator = options.sessionIdGenerator;
this._enableJsonResponse = options.enableJsonResponse ?? false;
this._eventStore = options.eventStore;
this._onsessioninitialized = options.onsessioninitialized;
}
/**
@ -328,9 +339,7 @@ export class StreamableHTTPServerTransport implements Transport {
// Check if this is an initialization request
// https://spec.modelcontextprotocol.io/specification/2025-03-26/basic/lifecycle/
const isInitializationRequest = messages.some(
msg => 'method' in msg && msg.method === 'initialize'
);
const isInitializationRequest = messages.some(isInitializeRequest);
if (isInitializationRequest) {
// If it's a server with session management and the session ID is already set we should reject the request
// to avoid re-initialization.
@ -359,6 +368,12 @@ export class StreamableHTTPServerTransport implements Transport {
this.sessionId = this.sessionIdGenerator();
this._initialized = true;
// If we have a session ID and an onsessioninitialized handler, call it immediately
// This is needed in cases where the server needs to keep track of multiple sessions
if (this.sessionId && this._onsessioninitialized) {
this._onsessioninitialized(this.sessionId);
}
}
// If an Mcp-Session-Id is returned by the server during initialization,
// clients using the Streamable HTTP transport MUST include it