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Client Killed the Server Star

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Most modern websites still place a large burden on the server, constantly sending it requests and asking it to do heavy computations. In the brave new world, the client is king and the server is its faithful shadow. In this talk, we'll look at how cutting-edge technology like Gears, HTML5, and Google App Engine can be used to create websites where the caching, storage, and computing is done primarily in the browser/desktop and the server is used merely as a backup store.

Presented at Webstock 2009.
Original version (not PPTed):
http://tr.im/clientkilledserver

Published in: Technology
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Client Killed the Server Star

  1. 1. Client Killed the Server Star http://tr.im/clientkilledserver @pamelafox
  2. 2. Web 1.0: The dumb client
  3. 3. Web 2.0: So Happy Together?
  4. 4. Web 3.0: The Server Sidekick
  5. 5. Why? The future is...
  6. 6. Server = Servant • Communications Hub • Sync state change between clients • Cached, Broad Queries (Not Fine-Grained) • Batch communication
  7. 7. How?
  8. 8. App Engine • Memcache • Request/Response • Datastore
  9. 9. Client = Master • Resource Storage • Data Storage • State Management • Heavy Computation • Dynamic Graphics • Bitmap Manipulation
  10. 10. How?
  11. 11. HTML 5 <!DOCTYPE HTML> <html> <head><title>HTML 5</title></head> <body>Hello World!</body> </html>
  12. 12. Gears LocalServer Database WorkerPool Blob Desktop Geolocation
  13. 13. Wrappers • Dojo (HTML5/Gears Database) • ActiveRecord (Gears/AIR/HTML5/JSON/Server DB) • HTML5/Gears (Manifest) • Excanvas (Canvas/VML) • RaphaelJS (VML/SVG)
  14. 14. Resource Storage Only ask the server for resources when the app's been updated. Resources = JS, CSS, HTML, IMGs, etc. • HTML 5: Application Cache, Manifest • Gears: LocalServer
  15. 15. HTML 5: Manifest Point to manifest file in HTML: <html manifest=”foo.manifest”> Create foo.manifest: CACHE MANIFEST # v1 # This is a comment. http://www.foo.com/index.html http://www.foo.com/header.png http://www.foo.com/blah/blah somethingElse.jpg Demo 
  16. 16. HTML 5: ApplicationCache Use ApplicationCache object and window.applicationCache: var appCache = window.applicationCache; if (appCache.status == ApplicationCache.UNCACHED) { alert("Not cached yet"); } appCache.oncached = function() { alert("Cached now!"); } Also available: update, swapCache, onchecking, onerror, onnoupdate, ondownloading, onprogress, onupdateready, oncached, onobsolete
  17. 17. Gears: LocalServer Use ResourceStore to grab array of files: var pageFiles = [ location.pathname, 'gears_init.js' ]; var localServer = google.gears.factory.create('beta.localserver', '1.0'); var store = localServer.openStore(this.storeName) || localServer.createStore(this.storeName); store.capture(pageFiles, function(url, success, captureId) { console.log(url + ' capture ' + (success ? 'succeeded' : 'failed')); }); Demo 
  18. 18. Gears: LocalServer Use ManagedResourceStore to use manifest file: var localServer = google.gears.factory.create('beta.localserver'); var store = localServer.createManagedStore(STORE_NAME); store.manifestUrl = 'manifest_v1.json'; store.checkForUpdate(); manifest_v1.json: { "betaManifestVersion": 1, "version": "v1", "entries": [ { "url": "managed_store.html", "src": "managed_store_v1.html" }, ...]} Demo 
  19. 19. Gears: LocalServer • FavIcoop 
  20. 20. Data Storage Persist data locally, both in DBs and hash tables.  Issue complex queries on the client, not on the server. • HTML 5: o localStorage  o Database  • Gears: Database 
  21. 21. HTML 5: localStorage Store strings in keys using Storage object &  window.localStorage: function doSave() { var filename = document.forms.editor.filename.value; var data = document.forms.editor.data.value; localStorage.setItem('file-' + filename, data); } function doOpen() { var filename = document.forms.editor.filename.value; document.forms.editor.data.value = localStorage.getItem('file-' + filename); } Also use: removeItem, clear, window.onstorage Demo 
  22. 22. HTML 5: Database Open DB with window.openDatabase, then use Database  object: var db = openDatabase("MyDB", "1.0", "Example", 200000); db = openDatabase("NoteTest", "1.0", "HTML5 Database API example", 200000); db.transaction(function (tx) { tx.executeSql("INSERT INTO WebKitStickyNotes (id, note, timestamp, left, top, zindex) VALUES (?, ?, ?, ?, ?, ?)", [note.id, note.text, note.timestamp, note.left, note.top, note.zIndex]); }); Demo 
  23. 23. Gears: Database Open DB, then execute SQL statements var db = google.gears.factory.create('beta.database', '1.0'); db.open('database-demo'); db.execute('create table if not exists Demo (Phrase varchar(255), Timestamp int)'); db.execute('insert into Demo values (?, ?)', [phrase, currTime]); var rs = db.execute('select * from Demo order by Timestamp desc'); Demo 
  24. 24. Gears: Database • Bloggears  • AutoDesk Draw  • MySpace Messages  Also: RTMilk, GMail/GDocs/GReader, Zoho,  WordPress, AJAX Helper 
  25. 25. State Management Store session data on the client. Server is stateless. • HTML 5: sessionStorage 
  26. 26. HTML 5: sessionStorage Use window.sessionStorage with Storage object: <form action="step3.html" method=post onsubmit="save(n2)"> Adjective: <input name=n2> <input type="submit" value="Next..."> </form> function save(element) { sessionStorage.setItem(element.name,element.value); } Also use: getItem, removeItem, clear, window.onstorage Demo 
  27. 27. Heavy Computation JS is surprisingly fast at non-DOM operations.  Proof: TSP Solver , Clustering, Spatial queries But if in-page JS isn't fast enough or locks up the UI, offload  the task into a worker. Use for: Encryption, DB tasks, Syncing, Farming • Web Workers  • Gears: WorkerPool 
  28. 28. Web Worker Spec Create a worker and send messages to it: var searcher = new Worker('searcher.js'); function search(query) { searcher.postMessage(query); } Respond to messages in worker JS: importScripts('io.js'); onmessage = function (event) { postMessage(get('search.cgi?' + event.data)); };
  29. 29. Gears: WorkerPool Create worker IDs in WorkerPool, send/receive messages: workerPool.onmessage = function(a, b, message) { insertRow('Async Result:' + message.body); }; var childId = workerPool.createWorkerFromUrl('worker.js'); workerPool.sendMessage(2501234, childId); // worker.js var wp = google.gears.workerpool; wp.onmessage = function(messageText, senderId, message) { wp.sendMessage(identity(message.body), senderId); }; function identity(stuff) { // do hard math with stuff } Demo 
  30. 30. Gears: WorkerPool Sudoku Prime Calculation Mandelbrot (with & without ) Others: GMail, MySpace
  31. 31. Dynamic Graphics Render graphics or manipulate bitmaps in JS. No servers or plugins needed to generate them. Both 2d and 3d graphics can be done in browser. • HTML 5: Canvas • SVG
  32. 32. HTML 5: Canvas Create <canvas> element: <canvas id="canvas" width="150" height="150"></canvas> Then call functions on CanvasRenderingContext2D: var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); ctx.fillStyle = "rgb(200,0,0)"; ctx.fillRect (10, 10, 55, 50); ctx.fillStyle = "rgba(0, 0, 200, 0.5)"; ctx.fillRect (30, 30, 55, 50); Also use: scale, rotate, translate, transform, createGradientPattern, bezierCurveTo, putImageData, filLText, etc. Demo 
  33. 33. HTML 5: Canvas Polygonzo MontageMaker Car Navigation More: Box2dJS , Yahoo Pipes, 3D w/ 2D
  34. 34. Get Involved! HTML 5/Web Worker: • Join mailing list. • Subscribe two twitter updates (@whatwg). • Experiment with features using nightly builds: • IE 8 beta, Opera Labs , MineField (FF), Webkit Gears: • Join the project. • Discuss in group. • Make real apps!

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