12. Persistence and State Management

Persistence is an important feature that many users simply can’t live without. It’s the reason that cookies were invented to create the illusion of continuity in the otherwise stateless Web. Whereas most LOB applications have persistence requirements, the underlying solution can vary from comma-separated values in files and settings in the system registry to records in a relational database and binary objects (BLOBs) stored in the Cloud.

Silverlight provides persistence through the use of isolated storage. Isolated storage is not Silverlight specific and has existed for many years as a client-specific virtual file system that provides safety by hiding the underlying operating system from the application. Within Silverlight, isolated storage is mapped to the underlying host file system and provides a façade that is consistent between platforms. That means you don’t have to concern yourself with the details of serializing a binary type to the OS X file system because isolated storage will handle it for you.