Perplexity MCP Server

/** * Server utility for handling SSE communication * * This module provides functionality to convert standard I/O from a child process * to Server-Sent Events (SSE) for real-time communication with clients. */ import { spawn } from 'child_process'; import express from 'express'; import cors from 'cors'; /** * Converts stdio from a child process to SSE events * @param {Object} options Configuration options * @param {number} options.port Port to run the server on * @param {string} options.stdioCmd Command to execute in the child process * @param {Object} options.logger Logger instance * @returns {Promise<void>} Promise that resolves when the server is started */ export async function stdioToSse({ port, stdioCmd, logger }) { const app = express(); app.use(cors()); // Set up SSE endpoint app.get('/sse', (req, res) => { res.setHeader('Content-Type', 'text/event-stream'); res.setHeader('Cache-Control', 'no-cache'); res.setHeader('Connection', 'keep-alive'); // Send a comment to keep the connection alive const keepAlive = setInterval(() => { res.write(': keepalive\n\n'); }, 15000); // Clean up on client disconnect req.on('close', () => { clearInterval(keepAlive); logger.info('Client disconnected from SSE'); }); // Add this client to our broadcast list clients.push(res); logger.info('Client connected to SSE'); }); // Set up API endpoint to forward requests to the MCP server app.use(express.json({ limit: '50mb' })); app.post('/api/*', (req, res) => { // Forward the request to the MCP server via stdin const message = JSON.stringify({ path: req.path.replace('/api', ''), method: req.method, headers: req.headers, body: req.body, }); if (childProcess && childProcess.stdin.writable) { childProcess.stdin.write(message + '\n'); logger.info(`Forwarded request to MCP server: ${req.path}`); } else { logger.error('Cannot forward request: Child process not available'); res.status(500).json({ error: 'MCP server not available' }); } }); // Start the server app.listen(port, () => { logger.info(`Server running on port ${port}`); }); // Keep track of connected clients for broadcasting const clients = []; // Spawn the child process const childProcess = spawn(stdioCmd, { shell: true }); // Handle stdout from the child process childProcess.stdout.on('data', (data) => { const message = data.toString(); logger.debug(`MCP stdout: ${message}`); // Broadcast to all connected clients clients.forEach((client) => { client.write(`data: ${JSON.stringify({ type: 'stdout', message })}\n\n`); }); }); // Handle stderr from the child process childProcess.stderr.on('data', (data) => { const message = data.toString(); logger.debug(`MCP stderr: ${message}`); // Broadcast to all connected clients clients.forEach((client) => { client.write(`data: ${JSON.stringify({ type: 'stderr', message })}\n\n`); }); }); // Handle child process exit childProcess.on('exit', (code) => { logger.info(`MCP server exited with code ${code}`); // Notify all clients clients.forEach((client) => { client.write(`data: ${JSON.stringify({ type: 'exit', code })}\n\n`); }); }); }