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Your browser, my storage

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HTML5 introduces the new trend of offline storage for applications and data.

HTML5 introduces the new trend of offline storage for applications and data.

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  • 1. Your browser, my storage a new approach on data storing Francesco Fullone ff AT ideato.it
  • 2. Who am I Francesco Fullone aka Fullo - PHP developer since 1999 - President - and Open Source Evangelist - CEO @ - Nerd and geek
  • 3. What we want is a lot of storage space, on the client, that persists beyond a page refresh and isn’t transmitted to the server. ~ M. Pilgrim
  • 4. Persistent local storage is one of the areas where client applications traditionally win against web applications.
  • 5. A jump in the past
  • 6. http://www.flickr.com/photos/betsyweber/4962298614/ Cookies are introduced in HTTP/1.0, limited to only 20 per domain and 4KB each.
  • 7. Cookies are sent to and from client at any connection. http://www.flickr.com/photos/dionhinchcliffe/4326080515
  • 8. Microsoft with Internet Explorer 6 introduced dHTML and the userData API to store up to 64KB of data
  • 9. Mozilla introduced with Firefox 2 the DOM Storage API, it will then know as Web Storage.
  • 10. Adobe, in 2002, created the Flash Cookies aka “Local Shared Objects” for Flash 6. Data storage increased to 100KB but it was difficult to be used.
  • 11. With Flash 8, in 2006, Adobe introduced the ExternalInterface to allow Js to access to the stored resources.
  • 12. Between 2005 and 2007 dojox.storage is written by Brad Neuberg as a Js->Flash bridge to manage bigger chunks of data (with user prompt over 1MB).
  • 13. Google created Gears in 2007, that introduced a database paradigm (based on SQLite) to the storage problem.
  • 14. All these storage systems had different APIs, a common platform is needed by all the browser vendors.
  • 15. The two approaches of storing: Application Cache Offline storage
  • 16. Application Caching involves saving the application's core logic and user-interface. http://www.whatwg.org/specs/web-apps/current- work/#applicationcache
  • 17. It is enabled by a file .manifest that declares which resources have to be saved locally. (limited to 5MB).
  • 18. CACHE MANIFEST # Explicitly cached entries CACHE: index.html stylesheet.css images/logo.png scripts/main.js # Resources that require the user to be online. NETWORK: login.php /myapi http://api.twitter.com # static.html will be served if main.php is inaccessible # offline.jpg will be served in place of all images in images/large/ FALLBACK: /main.php /static.html images/large/ images/offline.jpg
  • 19. Data storage is about capturing specific data, or resources the user has expressed interest in. http://www.flickr.com/photos/bfionline/2380398365/
  • 20. Approaches to Data Storage
  • 21. Web Storage is the simpler implementation of the Data Storage paradigm. http://dev.w3.org/html5/webstorage/
  • 22. Web Storage is based on a structure of key-value pairs like any JavaScript object. localStorage.setItem("bar", foo);
  • 23. Web Storage can save up to 5MB but only as strings. So we have to force a casting if needed. var bar = parseInt(localStorage["bar"]);
  • 24. Web Storage should be local based or session based. var bar = localStorage["bar"]; var foo = sessionStorage["foo"];
  • 25. sessionStorage mantains a storage area that's available for the duration of the web session. Opening a new window/tab will create a new session.
  • 26. localStorage relies only on client, so we have to track changes and use storage.events to sync server and client if needed.
  • 27. Web SQL Database is just an offline SQL implementation, based on SQLite. http://dev.w3.org/html5/webdatabase/
  • 28. this.db = openDatabase('geomood', '1.0', 'Geo', 8192); this.db.transaction(function(tx) {   tx.executeSql("create table if not exists checkins(id    integer primary key asc, time integer,    latitude float, longitude float, mood   string)",   [],                 function() { console.log("siucc"); } »   ); });
  • 29. Web SQL Database is not (yet) supported by Microsoft and Mozilla, instead it is on browsers based on webkit.
  • 30. IndexedDB is a nice compromise between Web Storage and Web SQL Database. http://www.w3.org/TR/IndexedDB/
  • 31. IndexedDB allows to create an index on a certain field stored in a standard key->value mapping.
  • 32. IndexedDB is promoted by all browsers vendor, but is not yet officially supported by anyone! Firefox 4 beta has a partial implementation.
  • 33. FileAPI or File Storage will give us a way to store a lot of data. http://www.w3.org/TR/FileAPI/
  • 34. File API includes FileReader and FileWriter APIs. Actually (FileReader) is partially supported only by Chrome.
  • 35. First steps on offline storage development. http://www.flickr.com/photos/45449692@N00/3161567381
  • 36. HTML 5 Confusion
  • 37. Detect if the storing feature is supported by the browser (with modernizr), otherwise degradate to something else. (ie. dojox.storage)
  • 38. http://www.flickr.com/photos/neate_photos/3529558272/ Protect against lost data, sync automatically.
  • 39. http://www.flickr.com/photos/doctorow/2686237951/ Automatically detect when users are online.
  • 40. Do not exceed in storing data, you can store binary data base64 encoded but remember the pitfalls in performance.
  • 41. Avoid race conditions. If possible use WebSQL to use its transactions features.
  • 42. ?
  • 43. phpDay 2011 12-14 Maggio 2011 www.phpday.it
  • 44. rate this talk: http://joind.in/2126 via Quinto Bucci 205 47023 Cesena (FC) info AT ideato.it www.ideato.it