It's 2008, and I'm still torn on this one. So I'm developing a web method that needs a complex type passed into it and returned from it. The two options I'm toying with are:
Pass and return actual business objects with both data and behavior. When wsdl.exe is run, it will automatically create proxy classes that contain just the data portion, and these will be automatically converted to and from my real business objects on the server side. On the client side, they will only get to use the dumb proxy type, and they will have to map them into some real business objects as they see fit. A big drawback here is that if I "own" both the server and client side, and I want to use the same set of real business objects, I can run into certain headaches with name conflicts, etc. (Since the real objects and the proxies are named the same.)
Forget trying to pass "real" business objects. Instead, just create simple DataTransfer objects which I will map back and forth to my real business objects manually. They still get copied to new proxy objects by wsdl.exe anyway, but at least I'm not tricking myself into thinking that web services can natively handle objects with business logic in them.
By the way - Does anyone know how to tell wsdl.exe to not make a copy of the object? Shouldn't we be able to just tell it, "Hey, use this existing type right over here. Don't copy it!"
Anyway, I've kinda settled on #2 for now, but I'm curious what you all think. I have a feeling there are way better ways to do this in general, and I may not even be totally accurate on all my points, so please let me know what your experiences have been.
Update: I just found out that VS 2008 has an option to reuse existing types when adding a "Service Reference", rather than creating brand new identical type in the proxy file. Sweet.
there is also an argument for separating the tiers - have a set of serializable objects that get passed to and from the web service and a translator to map and convert between that set and the business objects (which might have properties not suitable for passing over the wire)
Its the approach favoured by the web service software factory service factory and means that you can change your business objects without breaking the web service interface/contract