Passing objects to Web Services

Question

I'm just learning Web Services and have had some of my preconceptions wiped out in recent days. Here is what I'm wanting to do... I would like to create a custom class (MyClass) and have it stored in a seperate assembly. I would like for my client application to reference that assembly and work with MyClass before connecting with my Web Service. I would also like my Web Service to reference that assembly (server side). Ideally, I want to pass MyClass as an object to a Web Method as a parameter. When I first tried this, I got the 'Cannot implicitly convert....' errors during compile. I then tried boxing/unboxing them, and passing it as a System.Object object, and that gave me Xml Serialization errors. Can anyone tell me if what I'm trying to do is possible? The simple solution here would be to have my client app reference the class FROM the Web Service, but this would require the user to be connected, which isn't a luxury I can guarantee until they are ready to submit (pass the object). -James

spgilmore · Answer

Forgive me but all my experience so far is with other toolkits (Borland) so some of this may be erroneous. Yes I believe this is impossible. I had the same problem when I started with SOAP and found that this is a common misconception. Despite its name SOAP is not very object-oriented. In my experience you can only pass objects that do not have CODE attached to them. In some languages records / structures and objects are identical in others the difference is that records / structures cannot contain code - only data. So to pass OBJECTS between client and server I have used the following technique. Split your class into a superclass and a subclass. All data should reside in the superclass and all code should reside in the subclass. That way you can use the subclass by calling its methods in both the client and the server to manage the data but you just pass the superclass (data only) between the two. When I say code I mean methods of the object. Constructors and properties are considered data by SOAP and go in the superclass. I've had a lot of luck with this method and it keeps the code very clean.