MCP TypeScript Demo Server

import express from 'express'; import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'; import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js'; import { randomUUID } from 'node:crypto'; import { z } from 'zod'; import { search_papers, extract_info } from './index.js'; const app = express(); app.use(express.json()); // Create MCP server const server = new McpServer({ name: 'arxiv-paper-search', version: '1.0.0' }); // Define tool schemas const searchPapersSchema = { name: z.string().describe('Topic to search for'), max_results: z.number().optional().describe('Maximum number of results to return') }; const extractInfoSchema = { paper_id: z.string().describe('ID of the paper to extract information from') }; // Register tools server.tool( 'search_papers', 'Search for papers on arXiv based on a topic', searchPapersSchema, async ({ name: topic, max_results }) => { try { const results = await search_papers(topic, max_results); return { content: [ { type: 'text', text: JSON.stringify(results, null, 2) } ] }; } catch (error: any) { throw new Error(`Failed to search papers: ${error.message}`); } } ); server.tool( 'extract_info', 'Extract information from a specific paper', extractInfoSchema, async ({ paper_id }) => { try { const info = await extract_info(paper_id); return { content: [ { type: 'text', text: JSON.stringify(info, null, 2) } ] }; } catch (error: any) { throw new Error(`Failed to extract paper info: ${error.message}`); } } ); // Map to store transports by session ID const transports: Record<string, StreamableHTTPServerTransport> = {}; // MCP endpoint app.post('/mcp', async (req, res) => { try { const sessionId = req.headers['mcp-session-id'] as string; let transport: StreamableHTTPServerTransport; if (sessionId && transports[sessionId]) { transport = transports[sessionId]; } else { transport = new StreamableHTTPServerTransport({ sessionIdGenerator: () => randomUUID(), onsessioninitialized: (sid) => { console.log(`Session initialized with ID: ${sid}`); transports[sid] = transport; } }); transport.onclose = () => { const sid = transport.sessionId; if (sid && transports[sid]) { console.log(`Transport closed for session ${sid}, removing from transports map`); delete transports[sid]; } }; await server.connect(transport); } 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 app.get('/mcp', async (req, res) => { const sessionId = req.headers['mcp-session-id'] as string; if (!sessionId || !transports[sessionId]) { res.status(400).send('Invalid or missing session ID'); return; } const transport = transports[sessionId]; await transport.handleRequest(req, res); }); // Handle DELETE requests for session termination app.delete('/mcp', async (req, res) => { const sessionId = req.headers['mcp-session-id'] as string; if (!sessionId || !transports[sessionId]) { res.status(400).send('Invalid or missing session ID'); return; } try { const transport = transports[sessionId]; await transport.handleRequest(req, res); } catch (error) { console.error('Error handling session termination:', error); if (!res.headersSent) { res.status(500).send('Error processing session termination'); } } }); // Handle server shutdown process.on('SIGINT', async () => { console.log('Shutting down server...'); for (const sessionId in transports) { try { console.log(`Closing transport for session ${sessionId}`); await transports[sessionId].close(); delete transports[sessionId]; } catch (error) { console.error(`Error closing transport for session ${sessionId}:`, error); } } console.log('Server shutdown complete'); process.exit(0); }); const PORT = 3000; app.listen(PORT, () => { console.log(`MCP Server listening on port ${PORT}`); });