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Introduction to Node.js: perspectives from a Drupal dev

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I gave a talk on November 25, 2010, on Node.js, and related technologies, to the Vancouver Drupal Users Group. The talk ran through why node.js is useful for realtime web apps, how to get it and …

I gave a talk on November 25, 2010, on Node.js, and related technologies, to the Vancouver Drupal Users Group. The talk ran through why node.js is useful for realtime web apps, how to get it and Express up and running, and how to access data from Drupal and MongoDB.

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  • 1. Introduction to Node.js Perspectives from a Drupal dev Mike Cantelon, Vancouver Drupal Users Group, Nov. 25, 2010 Thursday, November 25, 2010
  • 2. I am: A longtime PHP dev Devop for The Georgia Straight Experimenting with JS/SSJS and HTML5 http://mikecantelon.com http://github.com/mcantelon Thursday, November 25, 2010
  • 3. WHY NODE.JS? Thursday, November 25, 2010
  • 4. wordsquared.com: Real-time HTML/JS Scrabble MMO Thursday, November 25, 2010
  • 5. The real-time web Real-time applications are an interesting web subset Examples: Twitter, Etherpad, games, monitoring Real-time paradigm will spawn new types of apps Thursday, November 25, 2010
  • 6. Three barriers to real-time Conventional languages can be slow Conventional web servers can be slow Conventional databases are slow Thursday, November 25, 2010
  • 7. Node.js eliminates two Conventional languages can be slow Conventional web servers can be slow Conventional databases are slow Thursday, November 25, 2010
  • 8. http://www.slideshare.net/Vodafonedeveloper/nodejs-vs-phpapache Node.js vs PHP/Apache Thursday, November 25, 2010
  • 9. So what exactly is Node.js? Server-side Javascript (SSJS) implementation “Asynchronous” (more on that later) Built using V8 (JS engine used in Chrome Browser) Thursday, November 25, 2010
  • 10. Advantages over PHP Javascript is a cleaner language Asynchronous execution increases performance Node.js is suitable for writing TCP/IP apps Thursday, November 25, 2010
  • 11. “Asynchronous”? Also known as “event-based” Think of it as defining actions triggered by events CPU spends less time waiting around Thursday, November 25, 2010
  • 12. More benefits of SSJS Requires less mental context switching for devs Allows sharing of logic between client and server side Server-side JQuery for screen scraping? Yes! Thursday, November 25, 2010
  • 13. What about that last barrier? Conventional languages are slow Conventional servers are slow Conventional databases are slow Thursday, November 25, 2010
  • 14. MongoDB is one solution MongoDB is generally faster than SQL databases MongoDB queries are written in Javascript, not SQL MongoDB works well with node.js Thursday, November 25, 2010
  • 15. And Drupal? Drupal is great for managing content Node.js has no killer CMS Node.js can pull data from Drupal (details later) Thursday, November 25, 2010
  • 16. This looks conceptually like... Thursday, November 25, 2010
  • 17. SSJS HELLO WORLD Thursday, November 25, 2010
  • 18. Node.js isn’t hard to learn Knowing Javascript is the hard part Node.js is accessible Express is a framework that makes Node.js easier Thursday, November 25, 2010
  • 19. Hello World in Node.js shell var sys = require('sys'); sys.puts('Hello world'); Thursday, November 25, 2010
  • 20. Node.js server Hello World var http = require('http'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello Worldn'); }).listen(8124, "127.0.0.1"); Thursday, November 25, 2010
  • 21. Hello World in Express var express = require('express'); var app = express.createServer(); app.get('/', function(req, res){ res.send('Hello World'); }); app.listen(8124); Thursday, November 25, 2010
  • 22. Why use Express? Handles routing and redirection Nice templating support Provides sessions Thursday, November 25, 2010
  • 23. Express Templating Support Supports EJS, HAML, SASS, Jade (HAML variant) Extend with app-specific helper functions Provides “partials” (subtemplates) Thursday, November 25, 2010
  • 24. app.get('/', function(req, res){ res.render('index.haml', { locals: { title: 'My Site' } }); }); Templating Example Thursday, November 25, 2010
  • 25. SETTING UP NODE.JS Thursday, November 25, 2010
  • 26. Installing Node.js OS X: build from source or brew install node Linux: build from source Build instructions at http://nodejs.org/#download Thursday, November 25, 2010
  • 27. Installing NPM NPM lets you easily install node.js modules OS X: brew install npm Instructions for manual install: http://mikecantelon.com/npm Thursday, November 25, 2010
  • 28. Installing Express npm install express Now the command express will set up an example Express app for you Thursday, November 25, 2010
  • 29. Installing MongoDB OS X: build from source or brew install mongodb Linux: http://www.mongodb.org/display/DOCS/ Quickstart+Unix npm install mongodb Thursday, November 25, 2010
  • 30. DRUPAL -> NODE.JS Thursday, November 25, 2010
  • 31. Drupal as a datastore One way Node.js and Drupal can work together is having Drupal be the storehouse for important content requiring long-term management Thursday, November 25, 2010
  • 32. Something like... Thursday, November 25, 2010
  • 33. Serve data, not just pages For realtime apps you’re going to want to serve chunks of data to the browser rather than whole pages Whole pages take longer to render and use more bandwidth to transmit Leverage the browser as much as possible Thursday, November 25, 2010
  • 34. Serving a page... 1. Browser requests a URL 2. Server grabs some data from a database and dresses it up as a page using a template. 3. Whole page gets sent back to browser Thursday, November 25, 2010
  • 35. ...vs Serving Data 1. Browser requests some data 2. Server sends back data 3. Browser templates data and outputs HTML into the existing page Thursday, November 25, 2010
  • 36. Where to serve data from Pulling Drupal data directly to the browser is quick to implement, but puts more stress on your Drupal stack The alternative is to pull Drupal data to node.js and cache using a datastore like MongoDB Data can then be relayed via AJAX or Socket.io Thursday, November 25, 2010
  • 37. DRUPAL DATA SHARING Thursday, November 25, 2010
  • 38. Javascript For Data Sharing JSON is the duct tape of the web drupal_to_js turns any chunk of data into JSON Drupal Views can output JSON via Views Datasource Thursday, November 25, 2010
  • 39. What JSON looks like { 'drupal': { 'language': 'PHP', 'license': 'GPL', 'developed_by': { 'individuals', 'organizations', 'companies' } } } Thursday, November 25, 2010
  • 40. Drupal pumping out JSON Thursday, November 25, 2010
  • 41. Example: RSS to JSON via Views Thursday, November 25, 2010
  • 42. What our example will do Use the Aggregator module to pull data from an RSS feed (specifically “Drupal Planet”) Use Views, via the Views JSON module, to publish the aggregator items as JSON data Thursday, November 25, 2010
  • 43. Install Views Datasource Thursday, November 25, 2010
  • 44. Add View Thursday, November 25, 2010
  • 45. Add Page Display and Path Thursday, November 25, 2010
  • 46. Add Paging Thursday, November 25, 2010
  • 47. Add Fields Thursday, November 25, 2010
  • 48. Set Style to JSON Thursday, November 25, 2010
  • 49. Set Feed/Category ID Thursday, November 25, 2010
  • 50. Save View and Check Path Thursday, November 25, 2010
  • 51. Demo use of Drupal/JSON... [demo] http://github.com/mcantelon/Drupalurk Thursday, November 25, 2010
  • 52. Hack for Paging (v6 beta2) function mytheme_preprocess_views_views_json_style_simple(&$vars) { global $pager_total, $pager_page_array; $element = $vars['view']->pager['element']; $vars['rows']['pager'] = array( 'total' => $pager_total[$element], 'current' => $pager_page_array[$element] ); } http://gist.github.com/581974 Views Datasource needs theme tweak to make paging work Stick the snippet below into your theme’s template.php Thursday, November 25, 2010
  • 53. Hack for Paging (v6 beta2) This enables you to add &page=<page number starting at 0> to JSON calls You can then implement your own JS paging Thursday, November 25, 2010
  • 54. Possible JSON View Uses Pull front-page content Pull content by taxonomy Pull recent comments Whatever else you can do with a view Thursday, November 25, 2010
  • 55. Pulling JSON into Node.js var sys = require('sys'), rest = require('restler-aaronblohowiak'), item, node rest.get('http://mikecantelon.com/jsontest/News') .addListener('complete', function(data) { for(item in data.nodes) { node = data.nodes[item].node sys.puts(node.Title) sys.puts(node.Body) } }) http://gist.github.com/608741 restler module allows easy HTTP JSON requests Thursday, November 25, 2010
  • 56. TALKING TO MONGODB Thursday, November 25, 2010
  • 57. Things to remember Can create databases and schema on-the-fly Queries are Javascript A “collection” is similar to an SQL DB’s “table” MongoDB has a shell so easy to experiment Thursday, November 25, 2010
  • 58. Doing something to data 1. Open server DB connection 2. Open database 3. Open collection 4. Do something to the collection Thursday, November 25, 2010
  • 59. Opening server DB connection var mongo = require('mongodb'); var port = mongo.Connection.DEFAULT_PORT; var db = new mongo.Db( 'classroom', new mongo.Server('localhost', port, {}), {} ); Thursday, November 25, 2010
  • 60. Opening database db.open(function(err, db) { // stuff gets done in here }); Thursday, November 25, 2010
  • 61. Opening a collection db.collection( 'students', function(err, collection) { // collection operations here } ); Thursday, November 25, 2010
  • 62. Removing from a collection collection.remove( function(err, collection) { // records are now gone! } ); Thursday, November 25, 2010
  • 63. Adding some records // make four students with random ages var names = ['Rick', 'Jane', 'Bob', 'Lisa']; var index; for (index in names) { collection.insert({ 'name': (names[index]), 'age': Math.round(Math.random(4)*10)+18 }); } Thursday, November 25, 2010
  • 64. Displaying data from records // display names collection.find({}, {}, function(err, cursor) { cursor.toArray( function(err, students) { var index; for(index in students) { sys.puts(students[index].name); }; } ); } ); Thursday, November 25, 2010
  • 65. DEPLOYING NODE.JS Thursday, November 25, 2010
  • 66. Node.js isn’t a daemon Like PHP, node.js doesn’t run as a daemon This means that naive deployment would require keeping a terminal open There are a number of ways to deal with this... Thursday, November 25, 2010
  • 67. Upstart (Ubuntu/some other distros) Make a config file for each app in /etc/init Name config file my_app.conf and set as executable Start app using: sudo start my_app Thursday, November 25, 2010
  • 68. Installing Upstart Ubuntu: apt-get install upstart Linux: http://upstart.ubuntu.com/download.html Thursday, November 25, 2010
  • 69. System V init script (the right way) rc.local/custom script (quick and dirty) Gnu screen (for temporary deployment) No Upstart? (Centos/some other distros) Thursday, November 25, 2010
  • 70. Requires adding a line to /etc/rc.local and a script Example line in rc.local triggers script at startup: su - mike -c "/home/mike/drupalchat/RUN.sh" & Script should set NODE_PATH if you’re using npm rc.local/custom script Thursday, November 25, 2010
  • 71. Example script #!/bin/bash cd /home/mike/drupalchat export NODE_PATH=/home/mike/root /usr/local/bin/node server.js Thursday, November 25, 2010
  • 72. Hotnode will restart node.js when you change a file Start app with hotloading: hotnode my_app.js Installation: npm install hotnode Hotnode Thursday, November 25, 2010
  • 73. BONUS! WEBSOCKETS Thursday, November 25, 2010
  • 74. What are WebSockets? WebSockets are an “HTML5” technology for two-way TCP/IP textual communication Modern browsers, like Chrome and Firefox 4, offer a Javascript WebSockets interface Thursday, November 25, 2010
  • 75. Why not just use AJAX? AJAX is a hack that uses HTTP for communication HTTP request/response cycle has a lot of overhead WebSockets increase speed, lessen bandwidth use Thursday, November 25, 2010
  • 76. Implementing with Socket.io Socket.io is a client/server websocket solution, using Node.js for the server side The client library tries WebSockets, but falls back to other mechanisms when talking to old browsers Thursday, November 25, 2010
  • 77. Questions? Ideas? Thursday, November 25, 2010
  • 78. Flickr Credits http://www.flickr.com/photos/sidehike/459483568/ http://www.flickr.com/photos/wysz/86758900/ http://www.flickr.com/photos/generated/291537716/ http://www.flickr.com/photos/gsfc/3720663082/ http://www.flickr.com/photos/skreuzer/354316778/ http://www.flickr.com/photos/ubookworm/455760111/ http://www.flickr.com/photos/batega/1596898776/ http://www.flickr.com/photos/batigolix/3778363253/ http://www.flickr.com/photos/wwworks/4472384764/ http://www.flickr.com/photos/19779889@N00/4398186065/ http://www.flickr.com/photos/theplanetdotcom/4878809615/ http://www.flickr.com/photos/estherase/177188677/ Thursday, November 25, 2010
  • 79. Resources Node.js, Express.js and MongoDB http://nodejs.org/ http://expressjs.com/ http://www.mongodb.org/ Socket.io http://socket.io/ This presentation http://mikecantelon.com/drupal-nodejs Thursday, November 25, 2010