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In its most simple form Isolated Storage allows you to save name value pairs and retrieve them at some other time the next time your app runs. Granted we could get into XML and text files etc but I'm going to stick with just name value pairs.

Isolated storage is a file system. It is called "isolated" because it is rooted to a specific directory which provides the sandbox required for browser security. [...]

Creating a base generic repository allowed me to centralize common IsolatedStorageFile operations that would be needed any time I wanted to save, retrieve, or delete any type of object from Isolated Storage in my application while still being strongly typed.

This MEF catalog behaves like the DeploymentCatalog with a few exceptions. First, it will save any XAP file to isolated storage whenever it retrieves one, and second, if the application is OOB and offline, it will automatically load the XAPs from isolated storage instead of trying to fetch them from the web.

Instead of building my own catalog from scratch, I decided to cheat a little bit and use some of the existing catalogs "under the covers."

I see a lot of question on the forums asking how to edit text files kept on their machine and then save these files back to a desired location using Silverlight. In Silverlight 2, you had to use the Isolated Storage to save a file locally on the user’s machine. The SaveFileDialog is a new dialog control in Silverlight 3 which allows the user to specify a file name and location to save a file. This control can be invoked only through a user interaction. Let us a see a simple demonstration of using the OpenFileDialog and the SaveFileDialog control.

Isolated storage does not differ that much from cookies. It’s basically a file store for Silverlight: Silverlight applications can store in the Isolated Storage files during a session and retrieve them in a later session. Isolated storage is a per-user per-application storage, meaning that when userA works with SilverlightAppA, he’ll have a different isolated storage from userB working with the same application. Isolated storage information is not deleted when you clear your temporary internet files, it can be deleted through the Silverlight configuration.

Silverlight 3 ships with out of browser support which is a particularly useful feature.  Combining OOB with the ability to detect network status can allow your users to consume your Web app without a connection.  Combining both of these features with Isolated Storage and the right design approach can provide a seamless Occasionally Connected application experience using Silverlight 3.

In part II of this article Malcolm Sheridan demonstrates how to save data locally using isolated storage and then updates the database using RIA services once you’re back online. If you remember in Part I he showed you how easy it is to detect network changes using Silverlight. 

Well here is part II. I thought it would be nice to use the networking capabilities of Silverlight to either save changes locally using IsolatedStorage when there is no network connection, and when the network is restored, propagating those changes up to the database using RIA Services. This is a very simple application, but I’m trying to show you what is possible.

In this project Sergey Barskiy implements an Isolated Storage based database for Silverlight.

The usage of this software is very simple. You create a new database by Calling CreateDatabase. You can add tables to the database by calling db.CreateTable<T> where T is the type of entity to be stored in table rows. You can save database by calling Save, and open the database by calling OpenDatabase. This database supports version changes, so you can update your application and still be able to open the database. You can look for basic use of this database by examining test Silverlight application.

A DataForm is used which is bound with 2-way databinding and a UserSettings class with Validation Attributes. DataContractSerializer is used with IsolatedStorage.