NHibernate. DTO -> Domain

Question

Hello guys. I've got SOA which processing data for diff clients(asp,sl). The base of this design is domains of my business model. For transporting,showing it to clients I use DTO. For mapping domain to DTO I use AutoMapper. Now I should persist new entities from clients. I want use my DTO's at this scenario too. So i've got some questions as I'm not much familiar with this design

1) Is it a good practice build DTO on client and send it to web-service on the wire? MayBe i should pass my domains?

2) Is it possible have several DTO's to one domain (one show at grid, and one to save). For saving I need set all nonprimitive props at client.

3) DTO -> to Domain. If I've got int can I use AutoMapper to generate NHibernate Proxy for this ID, or I should do i manually.

Your expierence and practice are very interesting. Thanks for answer!!!

Answer 1

Your architecture gets more flexible using DTOs over the wire, in stead of domain model entities. You can have several DTOs per domain.

Answer 2

A good practice to use is screen and command specific DTOs.

An example of this would be when the user is looking at a customer display screen there is a single DTO which contains all (or most if you need to lazy load some stuff) the information for that customer.

The value of this technique is that the data can come from multiple sources which allows you to model your domain as makes sense to you as opposed to how your screens are setup. It also allows you to change your domain without worrying about your screens as you just need to update the mappings.

Depending on your programming language there may be tools such a AutoMapper (for C#) which allow you to easily create the mappings between domain and DTOs.