Question

I wanted to know which would be best suitable – EDM or reflection provider for a project.
Definitely EDM is much simpler to develop over the database.But the problem is that,if we already have a data access layer over the database then we may have to change the existing architecture if chosen with EDM.So i wanted to know if there were any specific differences in using between entity data model or reflection provider to expose the data as Odata feed.

Answer 1

Reflection provider uses reflection to build model based on your class hierarchy. EDM provider uses directly the model created by the Entity Framework. If you have already a data access layer then I think you actually have three options:
– try using Reflection provider if it works great. Unfortunately I doubt it will work – it will change your objects but I don’t think it will send queries to the database. In addition to be able to update data you will need to implement IUpdatable interface
– with EDM/EF provider you would probably need to move all you data access layer to EF. This means you would probably have to get rid of the access layer you have. The benefit is that once done it should work pretty much out of the box (queries updated etc)
– finally you can implement a custom provider. There is a few interfaces you would have to implement which would act as a bridge between the WCF Data Service and your access layer. Note that it is quite a lot of work. Here is the first post in the series that describes how to do it: http://blogs.msdn.com/b/alexj/archive/2010/01/07/data-service-providers-getting-started.aspx