Delivered at Melbourne JavaScript User Group - August 2011. http://melbjs.eventbrite.com

1. JavaScript Everywhere
From Nose To Tail
Carl Husselbee - Sensis
Cliffano Subagio (@cliffano) - Shine Technologies

2. Citysearch.com.au

3. New Platform
Improved application performance
Better memory usage
Improved content publishing reliability
Zero content duplication
Improved user experience
(project is still ongoing...)

4. The Three Amigos
+ +

5. One JavaScript To Rule Them All

6. In A Nutshell

7. CouchDB
Document oriented
Schema free
Design document in JavaScript
Incremental replication
HTTP API

8. Document
Simply a JSON object
{
"_id": "listing-123",
"_rev": "D1C946B7",
"business_name": "Wolfgang Puck",
"desc": "Fine dining and casual dining...",
"rating": 5,
"city": "Melbourne"
}
Stays as JSON on all layers

9. Replication
Content publishing - replication rule
curl -X POST "http://host/_replicate"
-d '{"source": "db-src", "target": "db-target", "continuous": true}'
-H "Content-Type: application/json"
Content indexing - continuous changes feed
curl -X GET "http://host/db/_changes?feed=continuous&since=123"

10. Design Document
A simple map reduce
"views": {
"melbourne_rating": {
"map": function (doc) {
if (doc.city === 'Melbourne') { emit(null, doc.rating); }
},
"reduce": function (key, values, rereduce) {
return sum(values);
}}}
Highly testable
Easy to mock up

11. Cradle
CouchDB client for Node.js
Uses CouchDB REST API
Asynchronous
Built-in caching

12. Node.js
Server-side JavaScript
Based on V8
Single Threaded
Non-blocking I/O

13. Single Threaded
No more thread deadlock
More predictable app server memory usage
Like Nginx vs Apache

14. Non-blocking I/O
I/O is expensive
Traditional web app wastes time on I/O
// blocking // non-blocking
var listings = db.getListings(); var callback = function
render(listings); (listings) {
render(listings);
}
db.getListings(callback);
Node.js provides non-blocking API

15. The Callback Trap

16. Nested Callbacks
var util = require(‘util’), listingId = 'listing-123';
function commentsCb(err, result) {
if (err) {
} else {
console.log('Comments: ' + util.inspect(result));
}
}
function listingCb(err, result) {
if (err) {
} else {
console.log('Listing: ' + util.inspect(result));
db.getComments(listingId, commentsCb)
}
}
db.getListing(listingId, listingCb);

17. A Better Way
Use control flow module
var async = require('async'), listingId = 'listing-123';
function getComments(cb) {
db.getComments(listingId, cb);
}
function getListing(cb) {
db.getListing(listingId, cb);
}
async.parallel({ comments: getComments, listing: getListing },
function (err, results) {
// results gives { listing: listingResult, comments: commentsResult }
});
Lots of other solutions: TameJS, Step, Seq, etc

18. Async In A Loop
This looks innocent
for (var i = 0; i < 1000000; i++) {
console.log('Meditate on this, you must!');
}

19. Async In A Loop
console.log is asynchronous
Node.js is faster than terminal display

20. Library Changes
Within the past one year:
Homegrown web framework >> Express
node-couch >> Cradle
Various template engines >> Jazz
Promises >> Callbacks + Async

21. Testing
Insanely fast even on slow PC
15,000 SLOC
100% test coverage
34 seconds
YUITest, JSCoverage, nodelint

22. Homegrown Modules
Jazz - template engine
{foreach doc in widget.docs}
{if (doc.type eq 'video')}
<span><a href="{doc.videourl}">{doc.title}</a></span>
{else}
<a href="{helper.createUrl(doc.key)}">
<h3>{doc.title}</h3>
</a>
{end}
{end}
No business logic
Synchronous compilation, asynchronous evalua

23. More Homegrown Modules
Log4js-node - logging framework
Severity level and rolling log file
Couchtato - CouchDB document utility tool
Doesn’t require CouchDB design doc knowledge

24. Continuous Integration
Jenkins Node.js Plugin
Nestor - Jenkins Node.js CLI

25. Conclusion
CouchDB rocks! Node.js rocks!
JavaScript web stack rocks!

26. Questions?

27. Resources
CouchDB - http://couchdb.apache.org
Node.js - http://nodejs.org
Jazz - http://github.com/shinetech/jazz
log4js-node - http://github.com/csausdev/log4js-node
Couchtato - http://github.com/cliffano/couchtato
Jenkins Node.js Plugin - https://wiki.jenkins-ci.org/display/JENKINS/NodeJS
+Plugin
Nestor - http://github.com/cliffano/nestor

28. Credits
http://www.flickr.com/photos/daveaustria/2654190796/ by Dave Austria
http://www.flickr.com/photos/38485387@N02/3580728177/ by flickrfavorites
http://www.housecontainer.nl/blog/about-me/127-dj-yoda-from-star-wars.html
http://www.miccicohan.net/blog/studio-antics-and-of-coursethe-rolling-stones/