@modelcontextprotocol/sdk
Version:
Model Context Protocol implementation for TypeScript
165 lines • 6.42 kB
JavaScript
;
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
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desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
const node_crypto_1 = require("node:crypto");
const mcp_js_1 = require("../../server/mcp.js");
const streamableHttp_js_1 = require("../../server/streamableHttp.js");
const z = __importStar(require("zod/v4"));
const types_js_1 = require("../../types.js");
const express_js_1 = require("../../server/express.js");
// Create an MCP server with implementation details
const getServer = () => {
const server = new mcp_js_1.McpServer({
name: 'json-response-streamable-http-server',
version: '1.0.0'
}, {
capabilities: {
logging: {}
}
});
// Register a simple tool that returns a greeting
server.tool('greet', 'A simple greeting tool', {
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.tool('multi-greet', 'A tool that sends different greetings with delays between them', {
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 = (0, express_js_1.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 && (0, types_js_1.isInitializeRequest)(req.body)) {
// New initialization request - use JSON response mode
transport = new streamableHttp_js_1.StreamableHTTPServerTransport({
sessionIdGenerator: () => (0, node_crypto_1.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);
});
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