Keep it simple. There isn’t much of a need to go out of your way adding extra layers of abstraction. Any data access framework or ORM you might be using will already be creating a good enough level of abstraction. With linq (IQueryable) being implemented in NHibernate, Entity Framework, or Linq to SQL, ORM du jour, you already have your a level of abstraction to your data source.
Need to query your read model from the client? Single page application maybe? Ok… you need one more layer. OData to the rescue. WCF Data Services provides an incredibly easy implementation with Entity Framework. ASP.NET Web API does have an OData implementation but has limitations.
Keep it simple:
- Data Source
- Data Access Layer (ORM)
- OData Layer – only if needed if client is making the query