Express Compatibility

Routup provides fromNodeHandler() and fromNodeMiddleware() to wrap existing Express or Connect middleware for use in routup.

fromNodeMiddleware()

Wrap a Node.js (req, res, next) middleware. The next() callback is bridged back into routup's pipeline:

import { Router, fromNodeMiddleware } from 'routup';
import cors from 'cors';

const router = new Router();

router.use(fromNodeMiddleware(cors()));

This works with any Express-compatible middleware:

import helmet from 'helmet';
import compression from 'compression';

router.use(fromNodeMiddleware(helmet()));
router.use(fromNodeMiddleware(compression()));

fromNodeHandler()

Wrap a Node.js (req, res) handler (without a next callback). If the handler writes a response, it is detected and the pipeline stops:

import { fromNodeHandler } from 'routup';

router.use(fromNodeHandler((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello from Node.js handler');
}));

How it Works

Both fromNodeHandler() and fromNodeMiddleware() access the underlying Node.js IncomingMessage and ServerResponse from the srvx runtime context. This means they only work when running on the Node.js runtime (i.e., when imported from routup/node).

The wrapper:

1. Extracts the Node.js req/res objects from event.request.runtime.node
2. Calls the middleware/handler with those objects
3. For fromNodeMiddleware(), bridges the next() callback back into routup's pipeline
4. Detects when the response has been fully written (via finish/close events)

This makes it straightforward to migrate from Express incrementally or reuse the existing middleware ecosystem.

Limitations

• Only works on Node.js (requires event.request.runtime.node from srvx)
• Middleware that depends on Express-specific extensions (e.g., req.app, req.baseUrl) may not work without modification