Storage¶

Two places to keep data, both from Microsoft.Xbox.Storage (Microsoft.Xna.Framework.Storage):

	Storage container	Cache container
Use for	Settings, favourites, PINs, resume positions	Downloaded images and responses
Lives on	The title's save area for the user	The console's cache partition
Survives	Until the user deletes it	Until the console clears the cache
Encrypted	Yes, per console	No
At a time	Any number	One per app

The runtime host doesn't implement isolated storage (its isolated-storage callbacks return "not implemented"), so use these instead of IsolatedStorageFile.

Both need GamerServices running; XboxApplicationFrame starts it (see App model).

Both are kept per title, so build on a runtime profile that keeps the donor's title (New-RuntimeProfile.ps1 -KeepTitle, see The app's title). A default profile declares no title, and an app built on it keeps its files in its own folder instead.

Storage container¶

var device = new StorageDevice();
device.BeginOpenContainer("My App", "MyApp", delegate(IAsyncResult ar)
{
    // The callback runs on another thread.
    Deployment.Current.Dispatcher.BeginInvoke(delegate
    {
        using (StorageContainer container = device.EndOpenContainer(ar))
        {
            using (Stream stream = container.CreateFile("settings.xml"))
            {
                settings.Save(stream);
            }
        }
    });
}, null);

• CreateFile and OpenFile return streams that encrypt and decrypt with a key bound to the console, so saved files can't be read on another console.
• FileExists, DeleteFile, GetFileNames and the directory methods work like System.IO.
• Open the container when you need it and dispose it afterwards. Favorites in samples\apps\CatalogBrowser wraps this pattern.

Cache container¶

CacheContainer.BeginOpenCacheContainer(delegate(IAsyncResult ar)
{
    Deployment.Current.Dispatcher.BeginInvoke(delegate
    {
        cache = CacheContainer.EndOpenCacheContainer(ar);   // keep it open
    });
}, null);

• One at a time: opening a second container while one is open throws InvalidOperationException. Open it once and keep it for the session, as PosterCache in samples\apps\CatalogBrowser does.
• It may disappear: the console can clear the cache partition at any time, so treat anything in it as re-downloadable.
• Cluster size: BeginOpenCacheContainer(format, bytesPerCluster, fileCacheSize, ...) sets the cluster size (4 KB to 64 KB, 4 KB by default). The drive is formatted when the size doesn't match.
• Unmounting: disposing the container unmounts the drive.

Tested¶

samples\PlatformCalls writes and reads back a file in each kind of container. samples\apps\CatalogBrowser keeps favourites in a storage container and posters on the cache drive. Both work under a current xenia-edge (see Status under xenia).