Javascript Everywhere From Nose To Tail
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This document summarizes the key benefits of using JavaScript across the full stack, from the database layer to the server and client-side applications. It highlights how CouchDB allows storing and querying JSON documents with JavaScript, and how Node.js enables building high-performance web servers with JavaScript. Asynchronous programming and control flow modules are discussed as techniques for managing callbacks. Testing and continuous integration are also covered.
Javascript Everywhere From Nose To Tail
- 1. JavaScript Everywhere From Nose To Tail Carl Husselbee - Sensis Cliffano Subagio (@cliffano) - Shine Technologies
- 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
- 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
- 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/