MCP Transport SSE Setup

Configure HTTP/SSE transport for web-based MCP servers.

Capabilities

• Configure SSE transport for MCP servers
• Set up HTTP endpoints for MCP communication
• Implement authentication middleware
• Configure CORS for browser clients
• Set up health check endpoints
• Implement connection management

Usage

Invoke this skill when you need to:

• Set up web-based MCP server transport
• Configure SSE for real-time communication
• Implement authentication for MCP endpoints
• Enable CORS for browser-based clients

Inputs

Parameter	Type	Required	Description
language	string	Yes	Target language (typescript, python)
framework	string	No	Web framework (express, fastify, fastapi)
auth	object	No	Authentication configuration
cors	object	No	CORS configuration

Generated Patterns

TypeScript Express SSE Transport

import express from 'express';
import cors from 'cors';
import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';

const app = express();

// CORS configuration
app.use(cors({
  origin: process.env.ALLOWED_ORIGINS?.split(',') || '*',
  credentials: true,
}));

app.use(express.json());

// Store active connections
const connections = new Map<string, SSEServerTransport>();

// SSE endpoint
app.get('/sse', async (req, res) => {
  const connectionId = req.query.connectionId as string || crypto.randomUUID();

  // Set SSE headers
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');
  res.setHeader('X-Accel-Buffering', 'no');

  // Create transport
  const transport = new SSEServerTransport('/message', res);
  connections.set(connectionId, transport);

  // Create server instance for this connection
  const server = new Server(
    { name: 'my-mcp-server', version: '1.0.0' },
    { capabilities: { tools: {}, resources: {} } }
  );

  // Register handlers...
  registerToolHandlers(server);

  // Handle connection close
  req.on('close', () => {
    connections.delete(connectionId);
    transport.close();
  });

  // Connect transport
  await server.connect(transport);
});

// Message endpoint
app.post('/message', async (req, res) => {
  const connectionId = req.query.connectionId as string;
  const transport = connections.get(connectionId);

  if (!transport) {
    res.status(404).json({ error: 'Connection not found' });
    return;
  }

  try {
    await transport.handlePostMessage(req, res);
  } catch (error) {
    res.status(500).json({ error: 'Failed to process message' });
  }
});

// Health check
app.get('/health', (req, res) => {
  res.json({
    status: 'healthy',
    connections: connections.size,
    timestamp: new Date().toISOString(),
  });
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`MCP Server listening on port ${PORT}`);
});

Python FastAPI SSE Transport

from fastapi import FastAPI, Request, Response
from fastapi.middleware.cors import CORSMiddleware
from sse_starlette.sse import EventSourceResponse
from mcp.server import Server
from mcp.server.sse import SseServerTransport
import uuid
import asyncio

app = FastAPI()

# CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Store connections
connections: dict[str, SseServerTransport] = {}

@app.get("/sse")
async def sse_endpoint(request: Request):
    connection_id = request.query_params.get("connectionId") or str(uuid.uuid4())

    async def event_generator():
        transport = SseServerTransport("/message")
        connections[connection_id] = transport

        server = Server("my-mcp-server")
        register_handlers(server)

        try:
            async for event in transport.events():
                yield event
        finally:
            connections.pop(connection_id, None)

    return EventSourceResponse(event_generator())

@app.post("/message")
async def message_endpoint(request: Request):
    connection_id = request.query_params.get("connectionId")
    transport = connections.get(connection_id)

    if not transport:
        return Response(status_code=404, content="Connection not found")

    body = await request.json()
    await transport.handle_message(body)
    return Response(status_code=200)

@app.get("/health")
async def health():
    return {
        "status": "healthy",
        "connections": len(connections),
    }

Workflow

1. Configure framework - Set up web framework
2. Add CORS - Configure cross-origin requests
3. Create SSE endpoint - Set up event stream
4. Add message handler - POST endpoint for messages
5. Implement auth - Optional authentication
6. Add health check - Monitoring endpoint

Target Processes

• mcp-transport-layer
• mcp-server-bootstrap
• mcp-server-monitoring-debugging