import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
import express from "express";
import { createServer } from "../server/index.js";
import cors from "cors";
console.error("Starting SSE server...");
// Express app with permissive CORS for testing with Inspector direct connect mode
const app = express();
app.use(
cors({
origin: "*", // use "*" with caution in production
methods: "GET,POST",
preflightContinue: false,
optionsSuccessStatus: 204,
})
);
// Map sessionId to transport for each client
const transports: Map<string, SSEServerTransport> = new Map<
string,
SSEServerTransport
>();
// Handle GET requests for new SSE streams
app.get("/sse", async (req, res) => {
let transport: SSEServerTransport;
const { server, cleanup } = createServer();
// Session Id should not exist for GET /sse requests
if (req?.query?.sessionId) {
const sessionId = req?.query?.sessionId as string;
transport = transports.get(sessionId) as SSEServerTransport;
console.error(
"Client Reconnecting? This shouldn't happen; when client has a sessionId, GET /sse should not be called again.",
transport.sessionId
);
} else {
// Create and store transport for the new session
transport = new SSEServerTransport("/message", res);
transports.set(transport.sessionId, transport);
// Connect server to transport
await server.connect(transport);
const sessionId = transport.sessionId;
console.error("Client Connected: ", sessionId);
// Handle close of connection
server.server.onclose = async () => {
const sessionId = transport.sessionId;
console.error("Client Disconnected: ", sessionId);
transports.delete(sessionId);
cleanup(sessionId);
};
}
});
// Handle POST requests for client messages
app.post("/message", async (req, res) => {
// Session Id should exist for POST /message requests
const sessionId = req?.query?.sessionId as string;
// Get the transport for this session and use it to handle the request
const transport = transports.get(sessionId);
if (transport) {
console.error("Client Message from", sessionId);
await transport.handlePostMessage(req, res);
} else {
console.error(`No transport found for sessionId ${sessionId}`);
}
});
// Start the express server
const PORT = process.env.PORT || 3001;
app.listen(PORT, () => {
console.error(`Server is running on port ${PORT}`);
});
