1823aae891Co-authored-by: Matt <77928207+mattzcarey@users.noreply.github.com> Co-authored-by: Konstantin Konstantinov <KKonstantinov@users.noreply.github.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
99 lines
4 KiB
TypeScript
99 lines
4 KiB
TypeScript
/**
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* Standalone GET stream + `notifications/resources/list_changed` (sessionful
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* 2025).
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*
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* One `NodeStreamableHTTPServerTransport` + `McpServer` per session, the way
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* you would deploy a sessionful 2025 server. The `add_resource` tool registers
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* a new resource on the session's instance — `McpServer.registerResource` emits
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* `notifications/resources/list_changed`, which on a sessionful transport
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* travels over the **standalone GET** SSE stream the client opened. The client
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* decides when to mutate (no timer race with the runner).
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*
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* **HTTP-only**, sessionful 2025 by definition — so the canonical
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* `serveStdio` / `createMcpHandler` shape does not apply (per-request stateless
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* has no GET stream).
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*/
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import { randomUUID } from 'node:crypto';
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import { parseExampleArgs } from '@mcp-examples/shared';
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import { createMcpExpressApp } from '@modelcontextprotocol/express';
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import { NodeStreamableHTTPServerTransport } from '@modelcontextprotocol/node';
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import { isInitializeRequest, McpServer } from '@modelcontextprotocol/server';
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import type { Request, Response } from 'express';
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import * as z from 'zod/v4';
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function buildServer(): McpServer {
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const server = new McpServer(
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{ name: 'standalone-get-example', version: '1.0.0' },
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{ capabilities: { resources: { listChanged: true } } }
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);
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let nextId = 1;
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const register = (name: string, content: string) =>
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server.registerResource(
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name,
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`https://mcp-example.com/dynamic/${encodeURIComponent(name)}`,
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{ mimeType: 'text/plain' },
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async uri => ({
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contents: [{ uri: uri.href, mimeType: 'text/plain', text: content }]
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})
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);
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register('initial', 'Initial content');
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server.registerTool(
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'add_resource',
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{
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description:
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'Register a new resource on this session — emits notifications/resources/list_changed over the standalone GET stream.',
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inputSchema: z.object({ content: z.string() })
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},
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async ({ content }) => {
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const name = `note-${nextId++}`;
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register(name, content);
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return { content: [{ type: 'text', text: `registered ${name}` }] };
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}
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);
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return server;
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}
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const sessions = new Map<string, NodeStreamableHTTPServerTransport>();
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const app = createMcpExpressApp();
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app.post('/mcp', async (req: Request, res: Response) => {
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const sid = req.headers['mcp-session-id'] as string | undefined;
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if (sid && sessions.has(sid)) {
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await sessions.get(sid)!.handleRequest(req, res, req.body);
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} else if (!sid && isInitializeRequest(req.body)) {
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const transport = new NodeStreamableHTTPServerTransport({
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sessionIdGenerator: () => randomUUID(),
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onsessioninitialized: id => {
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sessions.set(id, transport);
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}
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});
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transport.onclose = () => transport.sessionId && sessions.delete(transport.sessionId);
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await buildServer().connect(transport);
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await transport.handleRequest(req, res, req.body);
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} else if (sid) {
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res.status(404).json({ jsonrpc: '2.0', error: { code: -32_001, message: 'Session not found' }, id: null });
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} else {
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res.status(400).json({ jsonrpc: '2.0', error: { code: -32_000, message: 'Bad Request: Session ID required' }, id: null });
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}
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});
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// The standalone GET stream (the point of this story) and DELETE (explicit
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// session termination per the MCP spec) route to the session's transport.
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const sessionVerb = async (req: Request, res: Response) => {
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const sid = req.headers['mcp-session-id'] as string | undefined;
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const t = sid ? sessions.get(sid) : undefined;
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if (!t) {
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res.status(sid ? 404 : 400).send(sid ? 'Session not found' : 'Missing session ID');
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return;
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}
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await t.handleRequest(req, res);
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};
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app.get('/mcp', sessionVerb);
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app.delete('/mcp', sessionVerb);
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const { port } = parseExampleArgs();
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app.listen(port, () => {
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console.error(`[server] listening on http://127.0.0.1:${port}/mcp`);
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});
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