NodeJS and JavaScripteverywhere

Transcription

1 NodeJS and JavaScripteverywhere Matthew Eernisse YOW Conference: December 2011

2 Who am I? Matthew Eernisse Work at on Twitter

3 What is JavaScript- everywhere?

4 A list of stuff Ruby JavaScript Scala Java C# Rails NodeJS PostgreSQL Memcache Riak Redis BDB Vertica R

5 JavaScript at Yammer Browsers YamJS, a.k.a., YamJuice Adobe AIR Desktop V8 in Rails via TheRubyRacer NodeJS

6 Server JS

7 SSJS Netscape Enterprise Server (OG SSJS) Microsoft IIS Helma (now RingoJS) Whitebeam Zimki Jaxer Perservere Nitro Google App Engine CouchDB NodeJS

8 Why NodeJS? Death of Netscape Open source Yegge s NBL, Competition V8

9 NodeJS: Evented I/O for V8 JavaScript

10 Hello, NodeJS var http = require('http'); http.createserver(function (req, res) { res.writehead(200, {'Content-Type': 'text/plain'}); res.end('hello World\n'); }).listen(1337, " "); console.log('server running at ' + '

11 What can you do with Node?

12 EventEmitter Readable/WritableStream Callbacks

13 Jake build tool Tasks, prerequisites File tasks, directory tasks Namespaces PackageTasks Just executable JavaScript Async task execution (shell commands)

14 namespace('foo', function () { desc('this a sychronous task'); task('bar', function () { console.log('howdy'); }); }); desc('this an asychronous task'); task('baz', function () { require('child_process').exec('ls -l', function (err, stdout, stderr) { console.log(stdout); complete(); }); }, {async: true});

15 Geddy Web framework:

16 NodeJS at Yammer Upload service for files and images Realtime, collaborative documentediting feature Another, early-alpha service for mobile Web

17 Remote upload service Minimal v1 in prod, Nov Onboard thumbnailing, remote services for video and document post-processing Redis, CORS XHR-push or JSONP for upload-progress reporting

18 Realtime, collaborative documents feature In beta Oct. 21, 2011 EtherPad Lite ( etherpad-lite): NodeJS, Socket.io, PostgreSQL

19 Coding JS for Node

20 Flexibility

21 Async horror Even shelling out is async? Inside-out execution Evented and callback-based control-flow

22 Sync fetch-and-update var fetchandupdate = function (params) { var items = db.fetch(somequery); for (var i = 0, ii = items.length; i < ii; i++) { item.update(params); } return true; };

23 Async fetch-and-update var fetchandupdate = function (params, callback) { db.fetch(somequery, function (items) { var count = 0; for (var i = 0, ii = items.length; i < ii; i++) { item.update(params, function () { count++; if (count == ii) { callback(true); } }); } }); };

24 Is this familiar? jquery.ajax({ url: '/foo/bar.json', success: function () { alert('yay!'); } }); jquery('#foo').bind('click', function (e) { // Do some stuff });

25 Async patterns and libs Async queue Promise/deferred/future/eventual

26 Promise var p = new yammer.util.promise(); p.when('foo', 'bar', 'baz').then( function () { console.log('done!'); }); p.satisfy('foo'); p.satisfy('bar'); p.satisfy('baz'); p.then(function () { console.log('still done!'); });

27 Don t overdo it.

28 NodeJS in production

29 App dependencies NPM is awesome Third-party modules still may change rapidly Maintain forks, push back patches where appropriate

30 Assume you re fucked Callbacks in global scope have no stack

31 uncaughtexception handler Preemptible timeout-errors Timeout registry

32 Timeout registry Entries in an object with keys Per-item timeout Configurable polling-interval Define a timeout-handler

33 Timeout registry var TimeoutReg = require('timeout_registry').timeoutreg, handler = function (req, resp) { var registry = new TimeoutReg(function (key) { resp.writehead(500); resp.end('oops, something bad happened.'); }); registry('foo', 10000); performfoo(req, function (result) { if (result.ok) { registry.clear('foo'); // Do some other stuff resp.writehead(200); resp.end('hooray!'); } }); }; process.on('uncaughtexception', function (err) { // Do some kind of logging });

34 Visibility, metrics Measure everything Log everything

35 Ops Communicative, consultative dev Ask what is expected Be transparent Play nicely with others

36 Try it; you ll like it.

37 Matthew Eernisse Yammer Developer Center