Building servers with Node.js

Building Serverswith Node.js

Travis Swicegood

Licensed under Creative Commons,Attribution, Share-Alike

#nodetalk

some rights reservedbuilding servers with node.js

Hi, I’m Travis

#nodetalk

What’s thistalk about?

What isNode.js?

Servers

Is it RightFor Me?

What isNode.js?

Evented I/ONetworking

Toolkit

What’s “evented?”

Some Code

var db = new Database({host: "localhost"});db.connect();var result = db.find({name: "a-post"});// do something with result

Standard Data Store

var db = new Database({host: "localhost"});db.connect(function(conn) { conn.find({name: "a-post"}, function(result) { // do something with result });});

Evented Data Store

Event Loop

An Analogy

A rabbi, a priest, and a cowboy walk

into a bar.

Take 1Simple Bartender

Priest

Cowboy…

… he startsto talk

Bartender isnow blocked

Take 2Evented Bartender

Priest

Cowboy…

… he startsto talk

Bartender startsfilling orders

Fixing Take 1

Add more bartenders

Limit time with each client

Respond toEvents

Who uses this?

Memcached

Most NoSQL

Servers

Basic Socket Server

var net = require("net");net.createServer(function(socket) { socket.on("data", function(data) { socket.write("You said: " + data); socket.end(); }); socket.write("Please say something:\n");}).listen(1234);console.log("Listening on 1234");

Echo Server

Storing State

net.createServer(function(socket) { var name = false; socket.on("data", function(data) { if (!name) { name = data.toString('utf8').trim(); socket.write("Thanks, " + name + "\n"); socket.write("Please say something:\n"); } else { socket.write(name + ", you said: " + data); socket.end(); } }); socket.write("Please tell me your name: ");}).listen(1234);

Personalized Echo Server

Web Servers

Hello World

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/html"}); response.write("<h1>Hello, World!</h1>"); response.end();}).listen(4321);console.log("Now listening on port 4321");

Hello World

Something’sDifferent

Hello World

Any idea why?

Hello World

Hello World

Grokkingthe Request

Output the Request

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/plain"}); response.write(require("util").inspect(request)); response.end();}).listen(4321);console.log("Listening on 4321");

Output the Request

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/plain"}); response.write(require("util").inspect(request)); response.end();}).listen(4321);console.log("Listening on 4321");

Output the Request

$ curl -s http://localhost:4321/ { socket: { bufferSize: 0, fd: 7, type: 'tcp4', allowHalfOpen: true, _readWatcher: { socket: [Circular], callback: [Function: onReadable] }, readable: true, _writeQueue: [], _writeQueueEncoding: [], _writeQueueFD: [],… and so on, and so on …

Output the Request

$ curl -s http://localhost:4321/ … way down around line 148 … url: '/', method: 'GET',

Output the Request

$ curl -s http://localhost:4321/say?msg=Hello | grep "url:" url: '/say?msg=Hello',

Output the Request

Parsing the URL

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/plain"}); var parsedUrl = require("url").parse(request.url); response.write(require("util").inspect(parsedUrl)); response.end();}).listen(4321);console.log("Listening on 4321");

Parsing the URL

$ curl -s http://localhost:4321/say?msg=Hello { href: '/say?msg=Hello', search: '?msg=Hello', query: 'msg=Hello', pathname: '/say' }

Parsing the URL

Parsing the Query

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/plain"}); var parsedUrl = require("url").parse(request.url, true); response.write(require("util").inspect(parsedUrl)); response.end();}).listen(4321);console.log("Listening on 4321");

Parsing the Query

var http = require("http");http.createServer(function(request, response) { response.writeHead(200, {"Content-Type": "text/plain"}); var parsedUrl = require("url").parse(request.url, true); response.write(require("util").inspect(parsedUrl)); response.end();}).listen(4321);console.log("Listening on 4321");

Parsing the Query

$ curl -s http://localhost:4321/say?msg=Hello { href: '/say?msg=Hello', search: '?msg=Hello', query: { msg: 'Hello' }, pathname: '/say' }

Parsing the Query

Receiving Data

function(request, response) { var raw = ""; request.on("data", function(chunk) { raw += chunk; }); request.on("end", function() { var data = JSON.parse(raw), obj = {message: data.message.split("").reverse().join("")}; response.writeHead(200, {"Content-Type": "application/json"}); response.write(JSON.stringify(obj)); response.end(); });}

Receiving Data

Somethingis Wrong

$ node json-reverse.js Listening on 4321

undefined:0^SyntaxError: Unexpected end of input at Object.parse (native) at IncomingMessage.<anonymous> (/Book/code/servers/json-reverse.js:8:21) at IncomingMessage.emit (events.js:39:17) at HTTPParser.onMessageComplete (http.js:111:23) at Socket.ondata (http.js:945:22) at Socket._onReadable (net.js:654:27) at IOWatcher.onReadable [as callback] (net.js:156:10)

Can’t handle Errors

Fault-Tolerance

var handleResponse = function(response, code, message) { response.writeHead(code, {"Content-Type": "application/json"}); response.write(message); response.end();};

Quick Refactor

request.on("end", function() { if (!raw) { handleResponse(response, 400, "Requires more data"); return; } try { var data = JSON.parse(raw); } catch(e) { handleResponse(response, 400, "Invalid JSON"); return; } if (!data.message) { handleResponse(response, 400, "Requires a message"); return; }

var obj = {message: data.message.split("").reverse().join("") }; handleResponse(response, 200, JSON.stringify(obj)) });

Fault Tolerant Reverse

request.on("end", function() { if (!raw) { handleResponse(response, 400, "Requires more data"); return; } try { var data = JSON.parse(raw); } catch(e) { handleResponse(response, 400, "Invalid JSON"); return; } if (!data.message) { handleResponse(response, 400, "Requires a message");

// earlier code } catch(e) { handleResponse(response, 400, "Invalid JSON"); return; } if (!data.message) { handleResponse(response, 400, "Requires a message"); return; }

Libraries Help

Expressvisionmedia/express

var app = express.createServer();

app.get('/', function(req, res){ res.send('Hello World');});

app.listen(3000);

Hello World

Socket.IOhttp://socket.io/

var http = require('http'), io = require('socket.io');

Push from the Server

// socket.io var socket = io.listen(server); socket.on('connection', function(client){ // new client is here! client.on('message', function(){ … }) client.on('disconnect', function(){ … }) });

Socket.IO

// socket.io var socket = io.listen(server); socket.on('connection', function(client) { // send a message back to the client client.send({msg: "Thanks for connecting…"}); // broadcast a message to everyone client.broadcast({msg: "Another one connected!"});});

Sending to Client

CoffeeScriptjashkenas/coffee-script

request.on("end", function() { if (!raw) { handleResponse(response, 400, "Requires more data"); return; } try { var data = JSON.parse(raw); } catch(e) { handleResponse(response, 400, "Invalid JSON"); return; } if (!data.message) { handleResponse(response, 400, "Requires a message"); return; }

Remember this code?

request.on "end", () -> return handleResponse response, 400, "Requires more data" unless raw

try data = JSON.parse raw catch e return handleResponse response, 400, "Requires more data"

return handleResponse response, 400, "Requires a message" unless data.message

obj = message: data.message.split("").reverse().join("") handleResponse response, 200, JSON.stringify obj

In CoffeeScript

Vowscloudhead/vows

http://vowjs.org/

No Samples

Is it RightFor Me?

It Depends

The Checklist

Controlthe Stack

Comfortablewith Change

Full Control OverApp Logic

Lots of SmallIndependent

Pieces

Then Maybe

Where to?

nodejs.org

#Node.js (freenode)

Travis Swicegoodtravisswicegood.com

@[email protected]://joind.in/2810

Building servers with Node.js

Technology

Transcript of Building servers with Node.js