[VW 7.5] WSDL Question: How to allow subclasses?

I am trying to expose a new VW class as a WSDL service.  I’m having pretty good success, but I’m having a particular problem.

One of the Smalltalk classes I’m exposing is an object that will be passed to a client (as the result of a client command).  Let’s call this class MyResponse, and it has an instance variable that holds a collection of Subclasses of AbstractThing.  AbstractThing’s Smalltalk class hierarchy looks like this:

Object
                AbstractThing
                                ConcreteThing1
                                ConcreteThing2

AbstractThing defines an instance variable.  The subclasses do not define any instance variables.

MyResponse and AbstractThing both define a class method, #typePragmas, implemented like this:

typePragmas

                <pragmas: #instance>

                ^OrderedCollection new

                                add: #addAttribute:type:;

                                yourself

On the instance side, MyResponse has an instVar named #myThings, with accessor methods.  The setter method originally looked like this:

myThings: anOrderedCollectionOfThings
                myThings := anOrderedCollectionOfThings

Now, the collection of myThings actually holds instances of concrete subclasses of AbstractThing.  That is, it holds instances of ConcreteThing1, ConcreteThing2, etc.

When I expose MyResponse, I have to add an appropriate pragma to the setter method as described in the VW WebServices.pdf guide.  So this is what I did:

myThings: anOrderedCollectionOfThings
                <addAttribute: #myThings type: #(#Collection #AbstractThing)>

                myThings := anOrderedCollectionOfThings

Now, no matter how I run the Web Services Wizard (for “exposing an application as a web service”), the client’s MyResponse >> myThings contains an OrderedCollection of AbstractThing instances.  It never contains the actual subclass instances (of ConcreteThing1 and ConcreteThings2) that exist on the server side’s copy of the MyResponse object.

The question: What must I do to make the #myThings collection in the client’s MyResponse object contain instances of the AbstractThing subclasses?

Chris Winemiller
Master Developer/Process Control Group

1100 W. Campbell Rd.
Richardson, Tx 75080-2950

Ph. 469-624-4683