    /**
     * @author Ed Spencer
     * @class Ext.data.proxy.SessionStorage
     * @extends Ext.data.proxy.WebStorage
     *
     * <p>Proxy which uses HTML5 session storage as its data storage/retrieval mechanism.
     * If this proxy is used in a browser where session storage is not supported, the constructor will throw an error.
     * A session storage proxy requires a unique ID which is used as a key in which all record data are stored in the
     * session storage object.</p>
     *
     * <p>It's important to supply this unique ID as it cannot be reliably determined otherwise. If no id is provided
     * but the attached store has a storeId, the storeId will be used. If neither option is presented the proxy will
     * throw an error.</p>
     *
     * <p>Proxies are almost always used with a {@link Ext.data.Store store}:<p>
     *
    <pre><code>
    new Ext.data.Store({
        proxy: {
            type: 'sessionstorage',
            id  : 'myProxyKey'
        }
    });
    </code></pre>
     *
     * <p>Alternatively you can instantiate the Proxy directly:</p>
     *
    <pre><code>
    new Ext.data.proxy.SessionStorage({
        id  : 'myOtherProxyKey'
    });
     </code></pre>
     *
     * <p>Note that session storage is different to local storage (see {@link Ext.data.proxy.LocalStorage}) - if a browser
     * session is ended (e.g. by closing the browser) then all data in a SessionStorageProxy are lost. Browser restarts
     * don't affect the {@link Ext.data.proxy.LocalStorage} - the data are preserved.</p>
     */
    Ext.define('Ext.data.proxy.SessionStorage', {
        extend: 'Ext.data.proxy.WebStorage',
        alias: 'proxy.sessionstorage',
        alternateClassName: 'Ext.data.SessionStorageProxy',

        //inherit docs
        getStorageObject: function() {
            return window.sessionStorage;
        }
    });