Domain Services

Domain services are Windows Communication Foundation (WCF) services that encapsulate the business logic of a WCF RIA Services application. A domain service exposes a set of related operations in the form of a service layer. When you define a domain service, you specify the data operations that are permitted through the domain service.

When designing a domain service, you should think of the domain service as a set of related tasks that you expect users to perform in your application. Typically, such tasks involve a small group of closely-related entities. For example, in an expense reporting application, you might expose entities for expense reports, line items, and details. You might, then, place entities for accounts and payments in a separate domain service.

Domain Services and their Data Sources

The DomainService class is the base class for all classes that serve as domain services. To create a domain service that binds to a custom data object, you create a class that derives directly from DomainService. But if you have a domain service either binds an ADO.NET Entity model or that exposes a LINK to a SQL database, there are special abstract classes the derive from DomainService that you use instead.

• To create a domain service that binds to an ADO.NET Entity model, you create a class that derives from LinqToEntitiesDomainService. RIA Services provides the LinqToEntitiesDomainService class.
• If you want to create a domain services that exposes LINQ to SQL classes in your application, you create a class that derives from LinqToSqlDomainService. This class is provided in the RIA Services Toolkit. If you want to create a domain services that exposes LINQ to SQL classes in your application using this class, you must download the RIA Services Toolkit.