RIA Services pieces
Let us begin by defining RIA Services.
Formal definition (http://bit.ly/nmrOA9):
Microsoft WCF RIA Services simplifies the traditional n-tier application pattern by bringing together the ASP.NET and Silverlight platforms. RIA Services provides a pattern to write application logic that runs on the mid-tier and controls access to data for queries, changes and custom operations. It also provides end-to-end support for common tasks such as data validation, authentication and roles by integrating with Silverlight components on the client and ASP.NET on the mid-tier.
Now, we will define it more informally, according to our experience. The most usual case is that we have a database, probably running under SQL Server, and we create an Entity Framework model. If we limit ourselves to the server, it could be possible to throw queries from here and everything will be ready. What happens when using Silverlight? These are executed in a client machine within a sandbox, and are not able...