RESTful Services in Node.JS

Building services with Express. Best practices for avoiding callback hell. Sharing templates between client-side & server-side JavaScript code.

Transcript

1. RESTful Services in Node.js Nick Nisi Thursday, January 3, 13
2. Nick Nisi • @nicknisi • https://github.com/nicknisi • http://nicknisi.com • Thursday, January 3, 13
3. What is Node.js? What is Node.js? Thursday, January 3, 13
4. History • Invented in 2009 by Ryan Dahl • Currently maintained by Joyent Thursday, January 3, 13
5. ‣JavaScript on the Server ‣Asynchronous I/O ‣Event Driven ‣Built on top of Google’s V8 What is node.js? Thursday, January 3, 13
6. Node.js Pros/Cons • Write code in a single language for backend/ frontend • JavaScript is fun! • Can share frontend/backend code • No context switch between frontend/backend code • Non-blocking I/O is different and can be hard • Callback hell - hard to maintain code • missing/immature libraries Pros Cons Thursday, January 3, 13
7. Installing Node.js Thursday, January 3, 13
8. • Install binary • Build • homebrew (OS X) • brew install node Installing Node.js Thursday, January 3, 13
9. Getting Started With Node.js Thursday, January 3, 13
10. Hello World REPL File Execution Thursday, January 3, 13
11. Accessing Other Files var User = function (firstName, lastName) { this.firstName = firstName || ''; this.lastName = lastName || ''; }; User.prototype.getName = function () { return this.firstName + ' ' + this.lastName; }; module.exports = User; var User = require("./user"); var user = new User("Big", "Deal"); console.log("Hello, ", user.getName()); user.js hello.js Thursday, January 3, 13
12. • Comes with Node.js • Install packages / utilities/command line tools NPM npm install PACKAGE npm install -g PACKAGE ./node_modules /usr/local Thursday, January 3, 13
13. package.json { "name": "sample-app", "version": "0.0.1", "private": true, "scripts": { "start": "node app" }, "dependencies": { "express": "3.0.5", "less-middleware": "*", "hbs": "~2.0.1" } } npm install Thursday, January 3, 13
14. Express * all code examples available at https://github.com/nicknisi/node-talk Thursday, January 3, 13
15. Creating A New Express App npm install -g express express app Thursday, January 3, 13
16. Simple Express Server var express = require('express'); var app = express(); app.get('/', function (req, res) { res.send("Hello, World"); }); app.listen(3000); Thursday, January 3, 13
17. Simple Middleware var express = require("express"), fs = require('fs'); var app = express(); app.get('/', function (req, res) { res.send("Hello, World"); }); var middleware = function (req, res, next) { // do something important // or don't. // i'm a comment, not a cop fs.readFile(__dirname + '/name.txt', function (err, data) { req.name = data; next(); }); }; app.get('/foo', middleware, function (req, res) { res.send("Hello, " + req.name + " from the route!"); }); app.use(function (req, res) { res.writeHead(200, { "Content-Type": "text/plain" }); res.end('Hello, Middleware'); }); app.listen(3000); Thursday, January 3, 13
18. Variable URLs var express = require("express"); var app = express(); app.get('/', function (req, res) { res.send("Hello, World"); }); app.get('/greeting/:name/:location', function (req, res) { res.send("Hello, " + req.params.name + " from " + req.params.location); }); app.listen(3000); Thursday, January 3, 13
19. Using Templates npm install hbs --save <div id="wrapper"> <header> <h2>{{title}}</h2> </header> <div class="content"> <p>Hello, {{name}}</p> </div> </div> var express = require('express'); var app = express(); app.configure(function () { app.set('view engine', 'hbs'); }); app.get('/', function (req, res) { res.render("index", { title: 'Important Title', name: 'Bob' }); }); app.use(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain' }); res.end('Hello, Middleware'); }); app.listen(3000); index.hbs app.js Thursday, January 3, 13
20. Sharing Templates Between Frontend and Backend // register frontend partials, so they can be used on the backend var headerTmpl = fs.readFileSync(__dirname + '/public/templates/header.hbs', 'utf-8'); hbs.registerPartial('header', headerTmpl); <!DOCTYPE HTML> <html lang="en"> <head> <meta charset="UTF-8"> <title>Server Side Templates Example</title> <link rel="stylesheet" href="/stylesheets/ style.css"/> </head> <body> {{> header}} {{{body}}} </body> </html> Thursday, January 3, 13
21. Other Middleware npm install less-middleware --save var express = require('express'), lessMiddleware = require('less-middleware'); var app = express(); app.configure(function () { app.set('view engine', 'hbs'); app.use(lessMiddleware({ src: __dirname + '/public' })); app.use(express.static(__dirname + '/public')); }); app.get('/', function (req, res) { res.render("index", { title: 'Important Title', name: 'Bob' }); }); app.get('/greeting/:name', function (req, res) { res.render("index", { name: req.params.name}); }); app.use(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain' }); res.end('Hello, Middleware'); }); app.listen(3000); Thursday, January 3, 13
22. Callback Hell and the Promise(d) Land! Thursday, January 3, 13
23. Thursday, January 3, 13
24. var fs = require("fs"), resolve = require("path").resolve; var fileData = [], interval = null, done = false, fileDir = resolve(__dirname, 'files'); fs.readdir(fileDir, function (err, files) { if (err) { console.log("error finding files: " + err); } else { files.forEach(function (file, index) { console.log("filename: " + file); fs.readFile(resolve(fileDir, file), "utf8", function (err, data) { if (err) { console.log("error reading file: " + err); } else { fileData.push(data); if (index === files.length - 1) { done = true; } } }); }); interval = setInterval(function () { if (done) { fs.writeFile(resolve(__dirname, 'out.txt'), fileData.join("\n"), "utf8", function (err) { if (err) { console.log('Error writing file: ' + err); } else { console.log('done'); } clearInterval(interval); }); } else { console.log('not done yet'); } }.bind(this), 10); } }); Thursday, January 3, 13
25. var fs = require("fs"), comb = require("comb"), resolve = require("path").resolve; var fileData = [], interval = null, done = false, fileDir = resolve(__dirname, 'files'); var fsp = { readdir: comb.wrap(fs.readdir, fs), readFile: comb.wrap(fs.readFile, fs), writeFile: comb.wrap(fs.writeFile, fs) }; comb.async.forEach(fsp.readdir(fileDir), function (file, index) { var ret = new comb.Promise(); fsp.readFile(resolve(fileDir, file)).then(function (data) { fileData.push(data); ret.callback(); }); return ret.promise(); }).then(function () { fsp.writeFile(resolve(__dirname, 'out.promise.txt'), fileData.join("\n"), "utf8").then(function () { console.log('done'); }); }, function (err) { console.log("There was an error: " + err); }); Thursday, January 3, 13
26. Promises • help manage callback hell • encourages separation of success and failure logic • error-bubbling Comb provides plenty of methods for helping manage callbacks, as well as a million other things! http://c2fo.github.com/comb/index.html Thursday, January 3, 13
27. Examples Thursday, January 3, 13
28. Example App: NebraskaJS Tweets • written using ntwitter and socket.io modules • First time using socket.io and connecting to twitter stream • follows #nebraskajs tagged tweets in real time • Try it now! tweet #nebraskajs • Source available at nicknisi/nebraskajs- tweets Thursday, January 3, 13
29. NebraskaJS Tweets! Thursday, January 3, 13