Web Storage Sebastiano Armeli-Battana seba.armeli@gmail.com @sebarmeli Sunday, 20 February 2011

Remote Data Storage Sunday, 20 February 2011

Why Web Storage? • Performance • Speed • Reduced load on the servers • Offline applications • Transaction - HTTP stateless Sunday, 20 February 2011

History of Client-side Storage •HTTP Cookie • userData Behaviour in IE 5.5 • Local Shared Objects in Adobe Flash • Google Gears Sunday, 20 February 2011

Web Storage • by WHATWG / W3C • HTML5? Actually not... • 2 Storage Areas : • localStorage • sessionStorage • globalStorage HTML Sunday, 20 February 2011

Storage API interface Storage { readonly attribute unsigned long length; DOMString key(in unsigned long index); getter any getItem(in DOMString key); setter creator void setItem(in DOMString key, in any value); deleter void removeItem(in DOMString key); void clear(); }; Sunday, 20 February 2011

localStorage • localStorage.setItem(“key1”, “value1”); localStorage.setItem(“key2”, “value2”); • localStorage.getItem(“key1”); // “value1” • localStorage.length; //2 • localStorage.removeItem(“key1”); • localStorage.length; // 1 • localStorage.clear(); • localStorage.length; // 0 Sunday, 20 February 2011

sessionStorage • sessionStorage.setItem(“key1”, “value1”); sessionStorage.setItem(“key2”, “value2”); • sessionStorage.getItem(“key1”); // “value1” • sessionStorage.length; //2 • sessionStorage.removeItem(“key1”); • sessionStorage.length; // 1 • sessionStorage.clear(); • localStorage.length; // 0 Sunday, 20 February 2011

Storing Objects • Key/value pairs • Value is a STRING! • Stringify / Parse JS Objects • JSON.stringify(myObject); • JSON.parse(myString); Sunday, 20 February 2011

Storage Event • “storage” event • Triggered when Storage Areas change • Binded on Window • Attributes: • key, • oldValue • newValue • url Sunday, 20 February 2011

Support • IE 8+ • FF 3.5+ • Safari 4+ • Chrome 7+ • Opera 10.6+ • iOS Safari 4.0+ / Android 2.2+ Sunday, 20 February 2011

JS Utilities • YUI2 Storage • Dojo Storage • PersistJS Sunday, 20 February 2011

Advantages (over Cookies) • Saving Bandwith • Size • Sessions not leaking • Network sniffing Sunday, 20 February 2011

Limitations • 5 Mb (or 10Mb) • “QUOTA_EXCEEDED_ERR” • “SECURITY_ERR” • Storage per origin • Cross directory attacks -> DO not USE it! • DNS Spoofing -> SSL Sunday, 20 February 2011

The future of Web Storage • Store data that rarely change • Mobile Sites • Offline apps • More Storage? Index Database API Sunday, 20 February 2011

Thank you. Sunday, 20 February 2011