Returning object obtained from a WCF web service

Question

I have a function that returns an entity obtained from a WCF web service. How should I return this entity as? I don't think I can return the original object (from the web service), because that would mean that the function's caller (from other assembly) will be forced to have a service reference to this web service (because the class is defined in the service reference) and I think I want to avoid that. And I don't think I can use interface either, since I can't modify the WCF entity to implement my interface.

On the other hand, I need to return precisely all properties that the original entity has, eg. all properties needed to be there, and there is no conversion/adjustment needed to any value or any property name and type.

Is it better to create a new class that duplicate the same properties from the original WCF class? How should I implement it, is it better to create a new object that copies all values from the original object, e.g.

return new Foo() { Id = original.Id, Name = original.Name, ... etc. }?

or just wrap it with get set methods like :

public int Id
{
   get { return _original.Id; }
   set { _original.Id = value; }
}

And any idea how to name the new class to avoid ambiguity with the original class name from the WCF reference?

or use something like Automapper to convert one class into another? — stephenl

Chintana Meegamarachchi Chintana Meegamarachchi · Accepted Answer · 2013-02-26T06:56:28

as you have figured out, it is not a good idea to force the client to use the same types as the server. This would unnecessarily expose server application architecture to the client. The best option is to use Data Transfer Objects (DTOs).

You may have DTO for each of the entity you wish to expose to the client and the DTO will have properties to expose all the required fields of the entity. There are libraries such as value injector (valueinjecter.codeplex.com) or auto mapper as suggested by @stephenl to help you in copying the values from one object to another.

Place the DTOs in a separate namespace and assembly for best physical decoupling. You can use YourCompany.YourProduct.Data.Entities as the namespace for entities and YourCompany.YourProduct.Data.DTO for the DTOs

Returning object obtained from a WCF web service

2 Answers