Einführung in Node.js

WER BIN ICH?

• Sebastian Springer

• https://github.com/sspringer82

• @basti_springer

• Teamlead @ Mayﬂower

Monday, March 11, 13

THEMEN
• Installation • Dateisystem

• Node.js Shell • Debugger

• Kernkomponenten • Child_Process

• NPM • Cluster

• Events • Tests

• Streams • Promises

• HTTP


https://github.com/sspringer82/
nodeworkshop


INSTALLATION


HTTP://NODEJS.ORG/
DOWNLOAD/


INSTALLATION
Auf welchen Systemen ist Node.js verfügbar?


INSTALLATION
• Unix • Windows

• /usr/local/bin/node • C:Program Filesnodejs
node.exe

• /usr/local/bin/npm • C:Program Filesnodejs
npm

• /usr/local/lib/node_modules • C:Program
Filesnodejs
node_modules


INSTALLATION

$ wget http://nodejs.org/dist/v0.8.21/node-v0.8.21.tar.gz
...
$ tar xvzf node-v0.8.21.tar.gz
...
$ cd node-v0.8.21/
$ ./configure --prefix=/opt/node/node-v0.8.21
...
$ make
...
$ sudo make install
...

Suchpfad anpassen!


INSTALLATION

Hat es funktioniert?

$ node --version
v0.8.22


WHAT?


READ-EVAL-PRINT-LOOP

DIE NODE.JS SHELL


REPL

$ node
> for (var i = 0; i < 3; i++) {
... console.log(i);
... }
0
1
2
undefined
>


REPL
.break Bricht ein Multiline Statement ab

.clear Zurücksetzen + .break (CTRL + C)

.exit Beendet die aktuelle Shell (CTRL + D)

.help Liste der Befehle

.save Speichert die aktuelle Session

.load Lädt eine gespeicherte Session


KERNKOMPONENTEN


KERNKOMPONENTEN
Standard Library

Node Bindings

V8 libuv

Eventloop async I/O


V8

• Schneller Zugriff auf Eigenschaften

• Dynamische Erstellung von Maschinencode

• Garbage Collection


V8 - FAST PROPERTY ACCESS


MASCHINENCODE


V8 - GARBAGE COLLECTION

• Programmausführung wird angehalten

• Es wird nur ein Teil des Object Heaps geprüft

• V8 kennt alle Objekte und Pointer im Speicher


KERNKOMPONENTEN
Standard Library

Node Bindings

V8 libuv

Eventloop async I/O

libev + libeio IOCP

ASYNCHRONE
OPERATIONEN
node.js Betriebssystem

Operation
(z.B. lesen)


APPLIKATIONEN IN NODE.JS



$ node helloWorld.js


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X X X
X X X
X X X
X X X
X X X


DAS MODULSYSTEM


DAS MODULSYSTEM

interne Module

eigene Module

NPM


INTERNE MODULE
Assertion Testing HTTP String Decoder
Buffer HTTPS Timers
Child_Process Net TLS/SSL
Cluster Os TTY
Crypto Path UDP
Debugger Process URL
DNS QueryString Utilities
Domain Readline VM
Event REPL ZLIB
File System Stream


INTERNE MODULE
STABILITÄTSINDEX
Index Name Beispiel
0 Deprecated util.pump
1 Experimental Domain, Cluster
2 Unstable Readline, Stream
3 Stable HTTP, Query String
4 API Frozen OS, Events
5 Locked Util, Assert


VERWENDUNG INTERNER
MODULE
intModule.js
var os = require('os');

console.log('Betriebssystem: ' +
os.type() + ' ' +
os.platform() + ' ' +
os.release() + ' ' +
os.arch());


INTERNE MODULE - GLOBALS

• console

• process

• require

• Buffer

• set/clear-Timeout/Interval

• __ﬁlename + __dirname


EIGENE MODULE


EIGENE MODULE

• OH: “Wenn ich mir das Zeug, das in Node programmiert
wurde, so ansehe, sieht das aus wie PHP3. Einfach von oben
nach unten, alles in einer Datei”

• Liegen in einer separaten Datei

• Exportieren Klassen, Objekte oder Funktionen

• Können an anderer Stelle eingebunden werden


EIGENE MODULE
validator.js

exports.email = function (email) {
var regex = /^([a-z0-9_.-]+)@([da-z.-]+).([a-z.]{2,6})$/,
result = regex.exec(email);

if (result) {
return true;
}

return false;
};


VERWENDUNG EIGENER
MODULE
modules.js

var validator = require('./validator.js'),
mail = ['sebastian.springer@mayflower.de', 'Invalid Address'];

for (var i = 0; i < mail.length; i++) {
if (validator.email(mail[i])) {
console.log((i + 1) + '. Mailadresse ist gültig');
} else {
console.log((i + 1) + '. Mailadresse ist ungültig');
}
}


EIGENE MODULE

$ node modules.js
1. Mailadresse ist gültig
2. Mailadresse ist ungültig


NPM

• Node Package Manager (von Isaac Schlueter)

• Bestandteil von Node.js seit 0.6.3

• https://github.com/isaacs/npm


NPM - REPO

• Hier kommen die Pakete für das npm-Kommando her

• https://npmjs.org/

• Aktuell über 24.000 Pakete

• https://registry.npmjs.org/-/all/


KOMMANDOS

• npm search <package>

• npm install <package>

• npm list

• npm update

• npm remove


NPM SEARCH
$ npm se mysql
npm http GET https://registry.npmjs.org/-/all/since?stale=update_aft...
npm http 200 https://registry.npmjs.org/-/all/since?stale=update_aft...
NAME DESCRIPTION AUTHOR DATE KEYWORDS...
Accessor_M... A MySQL database wrapper... =bu 2012-1... mysql ac...
any-db Database-agnostic connec... =grncdr 2013-0... mysql po...
autodafe mvc framework for node w... =jifeon 2012-1... mvc fram...
backbone-m... A sync module for Backbo... =ccowan 2012-1...
caminte ORM for every database: ... =biggor 2013-0... caminte ...
connect-my... a MySQL session store fo... =nathan 2012-0...
connect-my... A MySQL session store fo... =daniel 2011-0...
cormo ORM framework for Node.j... =croqui 2013-0... orm mong...


NPM INSTALL
$ npm in mysql
npm http GET https://registry.npmjs.org/mysql
npm http 200 https://registry.npmjs.org/mysql
npm http GET https://registry.npmjs.org/bignumber.js/1.0.1
npm http GET https://registry.npmjs.org/require-all/0.0.3
npm http 200 https://registry.npmjs.org/require-all/0.0.3
npm http GET https://registry.npmjs.org/require-all/-/requi...
npm http 200 https://registry.npmjs.org/bignumber.js/1.0.1
npm http GET https://registry.npmjs.org/bignumber.js/-/bign...
npm http 200 https://registry.npmjs.org/require-all/-/requi...
npm http 200 https://registry.npmjs.org/bignumber.js/-/bign...
mysql@2.0.0-alpha7 node_modules/mysql
!"" require-all@0.0.3
#"" bignumber.js@1.0.1


NPM LIST

$ npm ls
/srv/node
#"$ mysql@2.0.0-alpha7
!"" bignumber.js@1.0.1
#"" require-all@0.0.3


NPM UPDATE

$ npm up
npm http GET https://registry.npmjs.org/mysql
npm http 304 https://registry.npmjs.org/mysql
npm http GET https://registry.npmjs.org/require-all/0.0.3
npm http GET https://registry.npmjs.org/bignumber.js/1.0.1
npm http 304 https://registry.npmjs.org/bignumber.js/1.0.1
npm http 304 https://registry.npmjs.org/require-all/0.0.3


NPM REMOVE

$ npm rm mysql
$ npm ls
/srv/node
#"" (empty)


EIGENE NPM-PAKETE


{
"author": {
"name": "Felix Geisendörfer",
"email": "felix@debuggable.com",
"url": "http://debuggable.com/"
},
"name": "mysql",
"description": "A node.js driver for mysql...",
"version": "2.0.0-alpha7",
"repository": {
"url": ""
},
"main": "./index",
"scripts": {
"test": "make test"
},
"engines": {
"node": "*"
},
"dependencies": {
"require-all": "0.0.3",
"bignumber.js": "1.0.1"
},
"devDependencies": {
"utest": "0.0.6",
"urun": "0.0.6",
"underscore": "1.3.1"
},
"optionalDependencies": {},
"readme": "# node-mysqlnn[![Build Status]...",
"readmeFilename": "Readme.md",
"_id": "mysql@2.0.0-alpha7",
Monday, March 11, 13 "_from": "mysql"

EIGENE NPM-PAKETE

• npm adduser

• Username, Passwort, E-Mail

• npm publish <folder>|<tarball>


https://github.com/joyent/node/wiki/
Modules


EVENTS


EVENTS
Event Emitter Subscriber

on(‘message’, function (e) {...

emit(‘message’, ‘data’)


EVENTS

• Basis vieler Module

• Grundlage für eventgetriebene Architektur

• Ereignisse zum Informationsaustausch

• emit(event, [arg1], [arg2], [...]) - Publish

• on(event, listener) - Subscribe


EVENTEMITTER
messageBus.js

var EventEmitter = require('events').EventEmitter,
util = require('util');

var MessageBus = function () {};

util.inherits(MessageBus, EventEmitter);

exports.MessageBus = MessageBus;


EVENTEMITTER
events.js

var MessageBus = require('./messageBus.js').MessageBus;

var mb = new MessageBus();

mb.on('message', function (data) {
console.log('Received new message: ' + data)
});

mb.emit('message', 'Hello World');


EVENTEMITTER

$ node events.js
Received new message: Hello World


EVENTS

• Wo kommen Events zum Einsatz?

• child_process, cluster, dgram, domain, fs, http, net, readline,
repl, stream, tls


STREAMS


STREAMS

• Repräsentieren Datenströme in Node.js

• Abstraktes Interface

• Les- und/oder schreibbare Streams


READABLE STREAM

• Events • Methoden

• data • pause

• end • resume

• error • destroy

• close • pipe

• setEncoding


WRITABLE STREAM

• Events • Methoden

• drain • write

• error • end

• close • destroy

• pipe • destroySoon


STREAMS

• Wo kommen Streams zum Einsatz?

• fs, http, net repl, tls, zlib


STREAMS IN DER PRAXIS?


http://www.google.com


DER KLASSIKER


HTTP-SERVER
http.js

var http = require('http');

http.createServer(function (req, res) {
res.end('Hello World');
}).listen(8080);


HTTP-SERVER
$ node http.js


require('http').createServer(function (req, res) {
var body, status, reqData;

if (req.headers['user-agent'].search(/MSIE/) != -1) {
body = 'wrong Browser';
status = 403;
} else {
body = 'Hello Client';
status = 200;
}

req.on('data', function (data) {
reqData += data;
}).on('end', function () {
if (reqData) console.log(reqData);
});

res.writeHead(status, {
'Content-Length': body.length,
'Content-Type': 'text/plain' });
res.write(body);
res.end();
}).listen(8080);


HTTP-SERVER

• http.ServerRequest: Readable Stream

• http.ServerResponse: Writable Stream


HTTP-CLIENT?


DATEISYSTEM


DATEISYSTEM-FUNKTIONEN

• exists • unlink

• readFile • chmod

• writeFile • chown

• appendFile • ...

• watchFile

• rename


SYNC VS. ASYNC


DATEI LESEN

var fs = require('fs')
filename = process.argv[2] || 'input.txt';

fs.readFile(filename, 'utf8', function (err, data) {
if (err) {
console.error("File cound not be opened");
return false;
}
console.log(data);
return true;
});


DATEI LESEN

$ node readFile.js
Hello World!


DATEI LESEN

$ node readFile.js
Hello World!

$ node readFile.js nonexistant.txt
File cound not be opened


FILE EXISTS
$ ls -l input.txt
-rw-r--r-- 1 sspringer staff 12 Mar 7 09:06 input.txt


FILE EXISTS
$ ls -l input.txt

var fs = require('fs'),

fs.exists(filename, function (exists) {
if (exists) {
console.log('File exists');
return true;
}
console.error('There is no such file');
return false;
});


FILE EXISTS
$ ls -l input.txt


fs.exists(filename, function (exists) {
if (exists) {
console.log('File exists');
return true;
}
console.error('There is no such file');
return false;
});

$ node fileExists.js
File exists


APPEND FILE
$ cat input.txt
Hello World!


APPEND FILE
$ cat input.txt
Hello World!

data = process.argv[2] || 'Hello my World';

fs.appendFile('input.txt', data, function (err) {
if (err) {
console.error('Could not write into file');
return false;
}
console.log('Success!');
return true;
});


APPEND FILE
$ cat input.txt
Hello World!

data = process.argv[2] || 'Hello my World';

fs.appendFile('input.txt', data, function (err) {
if (err) {
console.error('Could not write into file');
return false;
}
console.log('Success!');
return true;
});

$ node appendFile.js 'Hallo München!'
Success!
$ cat input.txt
Hello World!Hallo München!

WATCH FILE
var fs = require('fs');

fs.watch('input.txt', function (e) {
if (e === 'change') {
console.log('File changed');
} else if (e === 'rename') {
console.log('File renamed');
}
});


WATCH FILE

}
});

$ node watchFile.js


WATCH FILE

}
});

$ node watchFile.js

$ echo 'Hello World!' > input.txt


WATCH FILE

}
});

$ node watchFile.js

$ echo 'Hello World!' > input.txt

$ node watchFile.js
File changed


DEBUGGER


BEISPIELCODE
var myObj = {a: 1, b: 2};

console.log(myObj);

myObj.a = 'Hello';

console.log(myObj);

for (var i = 0; i < 10; i++) {
var helper = function () {
// do something
console.log(i)
};
helper();
}


DEBUGGER

$ node debug debugger.js
< debugger listening on port 5858
connecting... ok
break in debugger.js:1
1 var myObj = {a: 1, b: 2};
2
3 console.log(myObj);
debug>


DEBUGGER - STEP

Kommando Bedeutung Beschreibung

n next Fortsetzen

c cont Step over

s step Step in

o out Step out


DEBUGGER - WATCH

• watch(expression)

• unwatch(expression)

• watchers


DEBUGGER - WATCH

debug> watch('myObj')
debug> n
Watchers:
0: myObj = {"b":2,"a":1}

1 var myObj = {a: 1, b: 2};
2
4
5 myObj.a = 'Hello';
debug>


DEBUGGER - REPL
debug> repl
Press Ctrl + C to leave debug repl
> myObj
{ b: 2, a: 1 }
> myObj.b = 14;
14
> myObj
{ b: 14, a: 1 }
debug> n
< { a: 1, b: 14 }
Watchers:
0: myObj = {"b":14,"a":1}

4
5 myObj.a = 'Hello';
6
debug>

DEBUGGER

• Kommandozeilen Debugger

• Kommandos

• Debugging einer Applikation


CHILD_PROCESS


CHILD_PROCESS

• spawn - Kommandoausführung

• exec - Kommandoausführung in Puffer

• execFile - Dateiausführung in Puffer

• fork - Node Prozess


ETWAS RECHENINTENSIVES
cp1.js
module.exports = function () {
var i, n = 1, results = 1;
primeLoop: while (results < 300000) {
n += 1;
for (i = 2; i <= Math.sqrt(n); i += 1) {
if (n % i === 0) {
continue primeLoop;
}
}
results += 1;
}
return n;
};


potenziell
ETWAS BLOCKIERENDES
cp2.js


http.createFakeServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(1337, '127.0.0.1');

console.log('Server running at http://127.0.0.1:1337/');


ETWAS BLOCKIERENDES
cp3.js
var http = require('http'),
prime = require('./cp1.js');

console.time('Request answered in');
console.log('incoming Request');

var number = prime();

res.end('Hello Worldn');

console.timeEnd('Request answered in');
}).listen(1337, '127.0.0.1');



ETWAS BLOCKIERENDES

$ node cp3.js
Server running at http://127.0.0.1:1337/
incoming Request
Request answered in: 4713ms
incoming Request


DIE LÖSUNG: WIR FORKEN


CHILD_PROCESS
cp4.js

console.time('Request answered in');
console.log('incoming Request');

require('child_process').fork('./primeHelper.js')
.on('message', function (data) {
res.end('The 300000st prime number is: ' + data.prime);

console.timeEnd('Request answered in');
});
}).listen(1337, '127.0.0.1');



CHILD_PROCESS
primeHelper.js

var prime = require('./cp1.js')();

process.send({'prime': prime});


CHILD_PROCESS

$ node cp4.js
Server running at http://127.0.0.1:1337/
incoming Request
incoming Request


CHILD_PROCESS

• Threadmodell von Node.js

• Möglichkeiten von child_process - fork, spawn, exec

• Kommunikation zwischen Eltern- und Kindprozess


CLUSTER


CLUSTER

• Loadbalancing über CPU

• Funktioniert mit allen Instanzen von “net.Server”

• ...auch mit http


cluster.js
var cluster = require('cluster'),
http = require('http'),
workers = 2;

if (cluster.isMaster) {
for (var i = 0; i < workers; i++) {
cluster.fork();
}
} else {
console.log('Worker ' + cluster.worker.process.pid + ' started');

http.createServer(function(req, res) {

console.log('Worker ' + cluster.worker.process.pid + '
responds');

res.writeHead(200);
res.end("hello worldn");
}).listen(8000);
}


clusterClient.js


for (var i = 0; i < 100; i++) {
http.get('http://localhost:8000', function (res) {
console.log(res);
});
}


CLUSTER

• node cluster.js

• node clusterClient.js


CLUSTER
Worker 38128 responds


TESTING


UNITTESTS

• Absicherung von Applikationen

• Tests auf Funktionsebene

• Node.js testet eigene Module ebenfalls

• Assert-Modul

• node-v0.8.22/test/simple


ASSERTION TESTING


ASSERTION TESTING

• var assert = require(‘assert’)

• Assertion-Methoden

• Sehr wenig Rückmeldung

• Nur ein Failure


ASSERTION TESTING
fail Wirft einen
AssertionError
ok(value, [message]) Pass, wenn der Wert
true ist
equal(actual, expected, [message]) Vergleich mit ==

deepEqual(actual, expected, [message]) Vergleich über
Strukturen
strictEqual(actual, expected, [message]) Vergleich mit ===

throws(block, [error], [message]) Pass, wenn eine
Exception geworfen
wird
NOT! - notEqual(...)

ASSERTION TESTING
assert.js

var assert = require('assert'),
actual = 'Hello World',
expected = 'Hello World';

assert.equal(actual, expected, 'Strings are not Equal');

assert.notEqual(actual, expected, 'Strings are Equal');

assert.fail('FAIL!', 'PASS!', 'This fails!');


ASSERTION TESTING
$ node assert.js

assert.js:102
throw new assert.AssertionError({
^
AssertionError: Strings are Equal
at Object.<anonymous> (/tmp/node/assert.js:7:8)
at Module._compile (module.js:449:26)
at Object.Module._extensions..js (module.js:467:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.runMain (module.js:492:10)
at process.startup.processNextTick.process._tickCallback (node.js:
244:9)


NODEUNIT


NODEUNIT

• npm install -g nodeunit

• Die gleichen Assertion-Methoden wie im Assert-Modul

• More verbose

• Mehrere Failures


module.exports = {
setUp: function (callback) {
console.log('setUp');
callback();
},
tearDown: function (callback) {
console.log('tearDown');
callback();
},
firstExample: function (test) {
console.log('firstExample')
test.equal('Hello', 'Hello', 'Strings are not Equal');
test.done();
},
exampleGroup: {
secondExample: function (test) {
test.notEqual('Hello', 'Hello', 'Strings are Equal');
test.done();
},
thirdExample: function (test) {
test.fail('FAIL!', 'PASS!', 'This fails!');
test.done();
}
}
}

$ nodeunit nodeunit.js

nodeunit.js
setUp
firstExample
tearDown
✔ firstExample
setUp
tearDown
✖ exampleGroup - secondExample

Assertion Message: Strings are Equal
AssertionError: 'Hello World' != 'Hello World'
at Object.assertWrapper [as notEqual] (...

setUp
tearDown
✖ exampleGroup - thirdExample

AssertionError: 'FAIL!' undefined 'PASS!'
at Object.assertWrapper [as fail] (...

FAILURES: 2/3 assertions failed (5ms)


PROMISES


PROMISES

• Ergebnis eines asynchronen Funktionsaufrufs

• Rückgabewert oder Exception

• Promise statt Blocking

• CommonJS Proposal

• Bis 0.2 Bestandteil von Node


PYRAMID OF DOOM

step1(function (value1) {
step2(value1, function (value2) {
// do something
});
});
});
});


PROMISES

Q.fcall(step1)
.then(step2)
.then(step3)
.then(step4)
.then(function (value4) {
// do something with value 4
}, function (error) {
// Handle any error from step1 through step4
})
.end();


PROMISE-LIBRARIES

• https://github.com/kriskowal/q

• https://github.com/kriszyp/node-promise (lightweight)

• https://github.com/kriszyp/promised-io (complete API)

• ...


OHNE PROMISES

fs.exists('input.txt', function (exists) {
fs.stat('input.txt', function (err, stats) {
fs.open('input.txt', 'r+', function (err, fd) {
fs.read(fd, new Buffer(stats.size), 0, stats.size, null,
function (err, read, buff) {
if (err) throw err;
console.log(buff.toString());
fs.close(fd, function () {
console.log('File Handle closed');
});
}
)
});
});
});


MIT PROMISES


AUSFÜHRUNG

$ node promises2.js
Hello World

File Handle closed


JETZT HABT IHR’S GESCHAFFT


FRAGEN?


KONTAKT
Sebastian Springer
sebastian.springer@mayflower.de

Mayflower GmbH
Mannhardtstr. 6
80538 München
Deutschland

@basti_springer

https://github.com/sspringer82


OHNE PROMISES


Einführung in Node.js

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