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- import { randomUUID } from 'node:crypto';
- import { McpServer } from '../../server/mcp.js';
- import { StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
- import * as z from 'zod/v4';
- import { isInitializeRequest } from '../../types.js';
- import { createMcpExpressApp } from '../../server/express.js';
- // Create an MCP server with implementation details
- const getServer = () => {
- const server = new McpServer({
- name: 'json-response-streamable-http-server',
- version: '1.0.0'
- }, {
- capabilities: {
- logging: {}
- }
- });
- // Register a simple tool that returns a greeting
- server.registerTool('greet', {
- description: 'A simple greeting tool',
- inputSchema: {
- name: z.string().describe('Name to greet')
- }
- }, async ({ name }) => {
- return {
- content: [
- {
- type: 'text',
- text: `Hello, ${name}!`
- }
- ]
- };
- });
- // Register a tool that sends multiple greetings with notifications
- server.registerTool('multi-greet', {
- description: 'A tool that sends different greetings with delays between them',
- inputSchema: {
- name: z.string().describe('Name to greet')
- }
- }, async ({ name }, extra) => {
- const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms));
- await server.sendLoggingMessage({
- level: 'debug',
- data: `Starting multi-greet for ${name}`
- }, extra.sessionId);
- await sleep(1000); // Wait 1 second before first greeting
- await server.sendLoggingMessage({
- level: 'info',
- data: `Sending first greeting to ${name}`
- }, extra.sessionId);
- await sleep(1000); // Wait another second before second greeting
- await server.sendLoggingMessage({
- level: 'info',
- data: `Sending second greeting to ${name}`
- }, extra.sessionId);
- return {
- content: [
- {
- type: 'text',
- text: `Good morning, ${name}!`
- }
- ]
- };
- });
- return server;
- };
- const app = createMcpExpressApp();
- // Map to store transports by session ID
- const transports = {};
- app.post('/mcp', async (req, res) => {
- console.log('Received MCP request:', req.body);
- try {
- // Check for existing session ID
- const sessionId = req.headers['mcp-session-id'];
- let transport;
- if (sessionId && transports[sessionId]) {
- // Reuse existing transport
- transport = transports[sessionId];
- }
- else if (!sessionId && isInitializeRequest(req.body)) {
- // New initialization request - use JSON response mode
- transport = new StreamableHTTPServerTransport({
- sessionIdGenerator: () => randomUUID(),
- enableJsonResponse: true, // Enable JSON response mode
- onsessioninitialized: sessionId => {
- // Store the transport by session ID when session is initialized
- // This avoids race conditions where requests might come in before the session is stored
- console.log(`Session initialized with ID: ${sessionId}`);
- transports[sessionId] = transport;
- }
- });
- // Connect the transport to the MCP server BEFORE handling the request
- const server = getServer();
- await server.connect(transport);
- await transport.handleRequest(req, res, req.body);
- return; // Already handled
- }
- else {
- // Invalid request - no session ID or not initialization request
- res.status(400).json({
- jsonrpc: '2.0',
- error: {
- code: -32000,
- message: 'Bad Request: No valid session ID provided'
- },
- id: null
- });
- return;
- }
- // Handle the request with existing transport - no need to reconnect
- await transport.handleRequest(req, res, req.body);
- }
- catch (error) {
- console.error('Error handling MCP request:', error);
- if (!res.headersSent) {
- res.status(500).json({
- jsonrpc: '2.0',
- error: {
- code: -32603,
- message: 'Internal server error'
- },
- id: null
- });
- }
- }
- });
- // Handle GET requests for SSE streams according to spec
- app.get('/mcp', async (req, res) => {
- // Since this is a very simple example, we don't support GET requests for this server
- // The spec requires returning 405 Method Not Allowed in this case
- res.status(405).set('Allow', 'POST').send('Method Not Allowed');
- });
- // Start the server
- const PORT = 3000;
- app.listen(PORT, error => {
- if (error) {
- console.error('Failed to start server:', error);
- process.exit(1);
- }
- console.log(`MCP Streamable HTTP Server listening on port ${PORT}`);
- });
- // Handle server shutdown
- process.on('SIGINT', async () => {
- console.log('Shutting down server...');
- process.exit(0);
- });
- //# sourceMappingURL=jsonResponseStreamableHttp.js.map
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