Chapter 5. Exposing Data from the Server: Using WCF RIA Services
By their very nature, business applications are highly data-centric applications. Therefore, one of the primary concerns you will have when designing your application is to how it will consume data from a server.
If you're used to writing applications that communicate directly with a database (such as SQL Server), you may be surprised to find that there is no object in Silverlight to enable you to do so (
SqlConnection, OdbcConnection, etc.). This is because Silverlight is a client platform, designed to be run from within a browser anywhere in the world, and thus it does not make sense for it to be able to access databases directly (as databases are generally hidden behind a firewall). ...