Which layer of the application should contain DTO implementation

Question

Lately I\'ve been hearing a lot about DTOs and how useful they are but I can\'t find a good example of using it in ASP.NET context.

Let\'s say I use three tier architect

Answer 1

There should not be any conversion. You would just use Poco Objects as DTO.

EF works with Poco and they can be serialized by WCF.

They should be defined in an assembly that is refernced by all projects.

In ASP.NET MVC you would mapp to a ViewModel by using the Poco - DTO.