170 lines
6.8 KiB
Plaintext
170 lines
6.8 KiB
Plaintext
import { randomUUID } from 'node:crypto';
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import { McpServer } from '../../server/mcp.js';
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import { StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
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import { isInitializeRequest } from '../../types.js';
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import { createMcpExpressApp } from '../../server/express.js';
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// Factory to create a new MCP server per session.
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// Each session needs its own server+transport pair to avoid cross-session contamination.
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const getServer = () => {
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const server = new McpServer({
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name: 'resource-list-changed-notification-server',
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version: '1.0.0'
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});
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const addResource = (name, content) => {
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const uri = `https://mcp-example.com/dynamic/${encodeURIComponent(name)}`;
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server.registerResource(name, uri, { mimeType: 'text/plain', description: `Dynamic resource: ${name}` }, async () => {
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return {
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contents: [{ uri, text: content }]
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};
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});
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};
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addResource('example-resource', 'Initial content for example-resource');
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// Periodically add new resources to demonstrate notifications
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const resourceChangeInterval = setInterval(() => {
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const name = randomUUID();
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addResource(name, `Content for ${name}`);
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}, 5000);
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// Clean up the interval when the server closes
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server.server.onclose = () => {
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clearInterval(resourceChangeInterval);
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};
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return server;
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};
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// Close sessions that have been idle for IDLE_MS, and keep at most MAX_SESSIONS open
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const IDLE_MS = 30 * 60000;
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const MAX_SESSIONS = 1000;
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const sessions = new Map();
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// Count open responses so a long-running request or a listening SSE stream is not treated as idle
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const trackResponse = (session, res) => {
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if (!res.socket || res.destroyed)
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return;
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session.open++;
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res.on('close', () => {
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session.open--;
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session.lastActive = Date.now();
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});
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};
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// Close sessions with nothing open and no activity for IDLE_MS
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setInterval(() => {
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const cutoff = Date.now() - IDLE_MS;
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for (const { transport, open, lastActive } of sessions.values()) {
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if (open === 0 && lastActive < cutoff)
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transport.close().catch(console.error);
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}
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}, 60000).unref();
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const app = createMcpExpressApp();
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app.post('/mcp', async (req, res) => {
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console.log('Received MCP request:', req.body);
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try {
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// Check for existing session ID
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const sessionId = req.headers['mcp-session-id'];
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const session = sessionId ? sessions.get(sessionId) : undefined;
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let transport;
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if (session) {
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// Reuse existing transport
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transport = session.transport;
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trackResponse(session, res);
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}
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else if (!sessionId && isInitializeRequest(req.body)) {
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// New initialization request
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if (sessions.size >= MAX_SESSIONS) {
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res.status(503).json({ jsonrpc: '2.0', error: { code: -32000, message: 'Too many open sessions' }, id: null });
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return;
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}
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transport = new StreamableHTTPServerTransport({
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sessionIdGenerator: () => randomUUID(),
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onsessioninitialized: sessionId => {
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// Store the transport by session ID when session is initialized
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// This avoids race conditions where requests might come in before the session is stored
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console.log(`Session initialized with ID: ${sessionId}`);
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sessions.set(sessionId, { transport, open: 0, lastActive: Date.now() });
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}
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});
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// Set up onclose handler to clean up transport when closed
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transport.onclose = () => {
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const sid = transport.sessionId;
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if (sid && sessions.has(sid)) {
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console.log(`Transport closed for session ${sid}, removing from sessions map`);
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sessions.delete(sid);
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}
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};
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// Create a new server per session and connect it to the transport
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const server = getServer();
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await server.connect(transport);
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// Handle the request - the onsessioninitialized callback will store the transport
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await transport.handleRequest(req, res, req.body);
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// If the transport rejected the request no session was created, so close it to stop the server's interval
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if (!transport.sessionId)
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await transport.close();
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return; // Already handled
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}
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else if (sessionId) {
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// Unknown or expired session ID - the client should start a new session
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res.status(404).json({ jsonrpc: '2.0', error: { code: -32001, message: 'Session not found' }, id: null });
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return;
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}
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else {
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// Invalid request - no session ID and not an initialization request
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res.status(400).json({
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jsonrpc: '2.0',
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error: {
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code: -32000,
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message: 'Bad Request: No valid session ID provided'
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},
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id: null
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});
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return;
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}
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// Handle the request with existing transport
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await transport.handleRequest(req, res, req.body);
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}
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catch (error) {
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console.error('Error handling MCP request:', error);
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if (!res.headersSent) {
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res.status(500).json({
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jsonrpc: '2.0',
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error: {
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code: -32603,
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message: 'Internal server error'
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},
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id: null
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});
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}
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}
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});
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// Handle GET requests for SSE streams (now using built-in support from StreamableHTTP)
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app.get('/mcp', async (req, res) => {
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const sessionId = req.headers['mcp-session-id'];
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if (!sessionId) {
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res.status(400).send('Missing session ID');
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return;
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}
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const session = sessions.get(sessionId);
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if (!session) {
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// Unknown or expired session ID - the client should start a new session
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res.status(404).json({ jsonrpc: '2.0', error: { code: -32001, message: 'Session not found' }, id: null });
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return;
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}
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console.log(`Establishing SSE stream for session ${sessionId}`);
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trackResponse(session, res);
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await session.transport.handleRequest(req, res);
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});
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// Start the server
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const PORT = 3000;
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app.listen(PORT, error => {
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if (error) {
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console.error('Failed to start server:', error);
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process.exit(1);
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}
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console.log(`Server listening on port ${PORT}`);
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});
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// Handle server shutdown
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process.on('SIGINT', async () => {
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console.log('Shutting down server...');
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for (const [sessionId, { transport }] of sessions) {
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await transport.close();
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sessions.delete(sessionId);
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}
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process.exit(0);
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});
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//# sourceMappingURL=standaloneSseWithGetStreamableHttp.js.map |