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feat: add closeSSEStream callback to RequestHandlerExtra (#1166)

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Felix Weinberger 2025-12-01 16:18:29 +00:00 • committed by GitHub
commit fab7e1e9b3
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1 changed files with 147 additions and 11 deletions
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18
src/examples/server/ssePollingExample.ts
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@ -7,7 +7,7 @@
* Key features:
* - Configures `retryInterval` to tell clients how long to wait before reconnecting
* - Uses `eventStore` to persist events for replay after reconnection
* - Calls `closeSSEStream()` to gracefully disconnect clients mid-operation
* - Uses `extra.closeSSEStream()` callback to gracefully disconnect clients mid-operation
*
* Run with: npx tsx src/examples/server/ssePollingExample.ts
* Test with: curl or the MCP Inspector
@ -31,9 +31,6 @@ const server = new McpServer(
}
);
// Track active transports by session ID for closeSSEStream access
const transports = new Map<string, StreamableHTTPServerTransport>();
// Register a long-running tool that demonstrates server-initiated disconnect
server.tool(
'long-task',
@ -65,11 +62,11 @@ server.tool(
await sleep(1000);
// Server decides to disconnect the client to free resources
// Client will reconnect via GET with Last-Event-ID after retryInterval
const transport = transports.get(extra.sessionId!);
if (transport) {
// Client will reconnect via GET with Last-Event-ID after the transport's retryInterval
// Use extra.closeSSEStream callback - available when eventStore is configured
if (extra.closeSSEStream) {
console.log(`[${extra.sessionId}] Closing SSE stream to trigger client polling...`);
transport.closeSSEStream(extra.requestId);
extra.closeSSEStream();
}
// Continue processing while client is disconnected
@ -112,6 +109,9 @@ app.use(cors());
// Create event store for resumability
const eventStore = new InMemoryEventStore();
// Track transports by session ID for session reuse
const transports = new Map<string, StreamableHTTPServerTransport>();
// Handle all MCP requests - use express.json() only for this route
app.all('/mcp', express.json(), async (req: Request, res: Response) => {
const sessionId = req.headers['mcp-session-id'] as string | undefined;
@ -123,7 +123,7 @@ app.all('/mcp', express.json(), async (req: Request, res: Response) => {
transport = new StreamableHTTPServerTransport({
sessionIdGenerator: () => randomUUID(),
eventStore,
retryInterval: 2000, // Client should reconnect after 2 seconds
retryInterval: 2000, // Default retry interval for priming events
onsessioninitialized: id => {
console.log(`[${id}] Session initialized`);
transports.set(id, transport!);