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Exposing existing class library to WCF service

Answer 1

A:

Helper classes that are not part of the hierarchy of the classes that are part of the operation contracts will never be exposed. As for child classes you could use the <knownType> section in web.config to instruct the serializer what are the possible child classes for a given base type:

<system.runtime.serialization>
    <dataContractSerializer>
      <declaredTypes>
        <add type="SomeNs.MyBaseType, SomeNs">
          <knownType type="SomeNs.MyChildType1, SomeNs"/>
          <knownType type="SomeNs.MyChildType2, SomeNs"/>
        </add>
        <add type="SomeNs.MyBaseType2, SomeNs">
          <knownType type="SomeNs.MyChildType3, SomeNs"/>
        </add>
      </declaredTypes>
    </dataContractSerializer>
</system.runtime.serialization>

WCF will look at the types that are part of the operation contracts (the methods marked with [OperationContract]) and it will automatically expose those classes in the metadata (WSDL) so that clients will see them. Possible child classes need to be specified explicitly.

Also you might find this blog post helpful.

Darin Dimitrov 2010-07-05 06:21:45

I'm self-hosting my wcf service. What part of App.Config should I put system.runtime.serialization?

powerbox 2010-07-05 06:25:06

Directly at the root: `<configuration><system.runtime.serialization>...</configuration>`

Darin Dimitrov 2010-07-05 06:25:53

I'm going to test your suggestions. Thanks! If this works, I need to add a whole lot of classes on my App.Config.

powerbox 2010-07-05 06:28:06

Thanks Darin! It worked perfectly, though the client side can't use my helper classes they can use now my child classes.

powerbox 2010-07-05 07:04:11

I would recommend you externalize your helper classes in a separate assembly. This will allow you to reuse it in your client application (assuming the client is written in .NET of course).

Darin Dimitrov 2010-07-05 07:06:22

Darin got some problems again. My child classes only exposed 0 arguments on its constructor and it initializes its base class using constants but it seems that in WCF client class creation, this does not apply, my member variables are all set to null. This is really the behavior of class instantiation if it is exposed on WCF?

powerbox 2010-07-05 07:37:08

The entities that are transported over the wire must have a default constructor because it is the only one that will be used by the serializer. They should be plain POCO objects. As you can see it's not that easy to expose an existing class library :-)

Darin Dimitrov 2010-07-05 08:04:18

Thanks! @_@ I thought I'm going to save more time but turn out it is not. Anyway thanks for the answers , it helps me a lot!.

powerbox 2010-07-05 08:33:41

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