import type { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
import express from "express";
export const startSSEMcpServer = async (
server: Server,
endpoint = "/sse",
port = 1122,
): Promise<void> => {
const app = express();
app.use(express.json());
const transports: Record<string, SSEServerTransport> = {};
app.get(endpoint, async (req, res) => {
try {
const transport = new SSEServerTransport('/messages', res);
transports[transport.sessionId] = transport;
transport.onclose = () => delete transports[transport.sessionId];
await server.connect(transport);
} catch (error) {
if (!res.headersSent) res.status(500).send('Error establishing SSE stream');
}
});
app.post('/messages', async (req, res) => {
const sessionId = req.query.sessionId as string;
if (!sessionId) return res.status(400).send('Missing sessionId parameter');
const transport = transports[sessionId];
if (!transport) return res.status(404).send('Session not found');
try {
await transport.handlePostMessage(req, res, req.body);
} catch (error) {
if (!res.headersSent) res.status(500).send('Error handling request');
}
});
app.listen(port, () => {
console.log(`SSE Server listening on http://localhost:${port}${endpoint}`);
});
};
