@modelcontextprotocol/sdk
Version:
Model Context Protocol implementation for TypeScript
142 lines • 5.53 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const express_1 = __importDefault(require("express"));
const node_crypto_1 = require("node:crypto");
const mcp_js_1 = require("../../server/mcp.js");
const streamableHttp_js_1 = require("../../server/streamableHttp.js");
const zod_1 = require("zod");
const types_js_1 = require("../../types.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: zod_1.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: zod_1.z.string().describe('Name to greet'),
}, async ({ name }, { sendNotification }) => {
const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms));
await sendNotification({
method: "notifications/message",
params: { level: "debug", data: `Starting multi-greet for ${name}` }
});
await sleep(1000); // Wait 1 second before first greeting
await sendNotification({
method: "notifications/message",
params: { level: "info", data: `Sending first greeting to ${name}` }
});
await sleep(1000); // Wait another second before second greeting
await sendNotification({
method: "notifications/message",
params: { level: "info", data: `Sending second greeting to ${name}` }
});
return {
content: [
{
type: 'text',
text: `Good morning, ${name}!`,
}
],
};
});
return server;
};
const app = (0, express_1.default)();
app.use(express_1.default.json());
// 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, () => {
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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