12.2.1 Node Example: HTTP Server

Node.js

// This is a simple NodeJS HTTP server that can serve files from the current
// directory and also implements two special URLs for testing.
// Connect to the server at http://localhost:8000 or http://127.0.0.1:8000
// First, load the modules we'll be using
var http = require('http'); // HTTP server API
var fs = require('fs'); // For working with local files
var server = new http.Server(); // Create a new HTTP server
server.listen(8000); // Run it on port 8000.
// Node uses the "on()" method to register event handlers.
// When the server gets a new request, run this function to handle it.
server.on("request", function (request, response) {
 // Parse the requested URL
 var url = require('url').parse(request.url);
 // A special URL that just makes the server wait before sending the 
 // response. This can be useful to simulate a slow network connection.
 if (url.pathname === "/test/delay") {
 // Use query string for delay amount, or 2000 milliseconds
 var delay = parseInt(url.query) || 2000;
 // Set the response status code and headers
 response.writeHead(200, {"Content-Type": "text/plain; charset=UTF-8"});
 // Start writing the response body right away
 response.write("Sleeping for " + delay + " milliseconds...");
 // And then finish it in another function invoked later.
 setTimeout(function() { 
 response.write("done.");
 response.end();
 }, delay);
 }
 // If the request was for "/test/mirror", send back the request verbatim.
 // Useful when you need to see the request headers and body.
 else if (url.pathname === "/test/mirror") {
 // Response status and headers
 response.writeHead(200, {"Content-Type": "text/plain; charset=UTF-8"});
 // Begin the response body with the request 
 response.write(request.method + " " + request.url + 
 " HTTP/" + request.httpVersion + "\r\n");
 // And the request headers
 for(var h in request.headers) {
 response.write(h + ": " + request.headers[h] + "\r\n");
 }
 response.write("\r\n"); // End headers with an extra blank line
 // We complete the response in these event handler functions:
 // When a chunk of the request body, add it to the response.
 request.on("data", function(chunk) { response.write(chunk); });
 // When the request ends, the response is done, too.
 request.on("end", function(chunk) { response.end(); });
 }
 // Otherwise, serve a file from the local directory.
 else {
 // Get local filename and guess its content type based on its extension.
 var filename = url.pathname.substring(1); // strip leading /
 var type; 
 switch(filename.substring(filename.lastIndexOf(".")+1)) { // extension
 case "html":
 case "htm": type = "text/html; charset=UTF-8"; break;
 case "js": type = "application/javascript; charset=UTF-8"; break;
     case "css": type = "text/css; charset=UTF-8"; break;
 case "txt" : type = "text/plain; charset=UTF-8"; break;
 case "manifest": type = "text/cache-manifest; charset=UTF-8"; break;
 default: type = "application/octet-stream"; break;
 }
 
 // Read the file asynchronously and pass the content as a single
 // chunk to the callback function. For really large files, using the
 // streaming API with fs.createReadStream() would be better.
 fs.readFile(filename, function(err, content) {
 if (err) { // If we couldn't read the file for some reason
 response.writeHead(404, { // Send a 404 Not Found status
 "Content-Type": "text/plain; charset=UTF-8"});
 response.write(err.message); // Simple error message body
 response.end(); // Done
 }
 else { // Otherwise, if the file was read successfully.
 response.writeHead(200, // Set the status code and MIME type
 {"Content-Type": type});
 response.write(content); // Send file contents as response body
 response.end(); // And we're done
 }
 });
 }
});