Starting the Express Server

To implement Express as the HTTP server for a Node.js application, you need to create an instance and begin listening on a port. The following three lines of code start a very rudimentary Express server listening on port 8080:

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var express = require('express'),
var app = express();
app.listen(8080);

The app.listen(port) call binds the underlying HTTP connection to the port and begins listening on it. The underlying HTTP connection is the same connection produced using the listen() method on a Server object created using the http library discussed in Chapter 7 “Implementing HTTP Services in Node.js.”

In fact, the value returned by express() is actually a callback function that maps to the callback function that is passed to the http.createServer() and https.createServer() methods.

Listing 18.1 shows how to implement a basic HTTP and HTTPS server using Node.js. Notice that the app variable that express() returns is passed into the createServer() methods. Also, notice that an options object is defined to set the host, key, and cert used to create the HTTPS server. Lines 13–15 implement a simple get route that handles the / path.

Listing 18.1 express_http_https.js: Implementing HTTP and HTTPS servers using Express

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01 var express = require('express'),
02 var https = require('https'),
03 var http = require('http'),
04 var fs = require('fs'),
05 var app = express();
06 var options = {
07     host: '127.0.0.1',
08     key: fs.readFileSync('ssl/server.key'),
09     cert: fs.readFileSync('ssl/server.crt')
10   };
11 http.createServer(app).listen(80);
12 https.createServer(options, app).listen(443);
13 app.get('/', function(req, res){
14   res.send('Hello from Express'),
15 });