To create a rest API from an Express NodeJS app just add a new js file to the routes folder, e.g. rest.js and add a call to to the app.js file:

var express = require('express');
var app = express();

app.use("/rest", rest.js)
app.use('/rest', rest);

To create a function which is first called on all requests add the following:

/* executed on all requests */
router.use(function(req, res, next) {
    console.log("There was a new request");

    // pass request on to our api
    next();
});

To create a GET method at /rest/yourMethod add the following to your rest.js file:

router.get('/yourMethod', function(req, res, next) {
    res.send('A return value');
});

Parameters can be read with req.params.your_param and the rest call needs to be modified for this to match something like this: ‘/yourMethod/:your_param’

To create a POST method at /rest/yourMethod:

router.post('/putPayload', function(req, res, next) {
    console.log(req.body.your_post_param);
    res.json( {result: "OK"} );
});

Note that req.body.your_post_param reads the parameter named your_post_param from the POST request.

A full example can be found on GitHub: https://github.com/ordsen/gsoc-preparation/tree/master/nodejs_server_example/interface

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