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.
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
