Errors/Warnings using svcutil.exe to create proxy classes for several WCF services

Question

I'm writing a .NET 3.5 app and have control over both the WCF service and client.

I'm using svcutil to generate proxy classes for my services, combining several services since they share data types.

svcutil /out:ServiceReference.cs /noconfig /namespace:*,Global.ServiceReference 
 /tcv:Version35 http://localhost:12345/first.svc http://localhost:12345/second.svc

The more serious problem is the error -- I've got a class being created twice, resulting lots of "Ambiguity between 'Global.ServiceReference.MyClass.MyField' and 'Global.ServiceReference.MyClass.MyField' " errors. Note that right now, this class is only referenced in ONE of the services, though in the future it will be referenced from more.

The two generated class look like:

[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Runtime.Serialization", "3.0.0.0")]
[System.Runtime.Serialization.DataContractAttribute(Name="MyClass", Namespace="http://schemas.datacontract.org/2004/07/MyService.Util")]
public partial class MyClass : object, System.Runtime.Serialization.IExtensibleDataObject
{ 
  //fields
}

and

[System.CodeDom.Compiler.GeneratedCodeAttribute("svcutil", "3.0.4506.2152")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://schemas.datacontract.org/2004/07/MyService.Util")]
public partial class MyClass
{
  // same fields
}

Based on the attributes applied to them, this has something to do with the DataContractSerializer vs. the XmlSerializer, but I don't really understand what those mean.

A second problem is that svcutil is giving a boatload of warnings of the form:

Error: There was a validation error on a schema generated during export:
    Source:
    Line: 1 Column: 10415
   Validation Error: The simpleType 'http://schemas.microsoft.com/2003/10/Serialization/:guid' has already been declared.

These errors happen even with two very simple services. For example, if service #1 has

[OperationContract]
public string test(int test)
{
    return "test";
}

and service #2 has

[OperationContract]
public int Ping(string test)
{
    return 23;
}

...I get the warnings. There's like a 100 of them, all complaining about various globalElements, globalAttributes, or simpleTypes like guid, duration, char, etc.

If I change one of the services to have only void parameters/return type, I don't get the warnings. This is really confusing, since this is the simplest possible test. Without using any custom types at all, svcutil is barfing. Any idea what's going on here?

Answer 1

Something in the XSD files is causing svcutil to invoke the XmlSerializer to generate some of your types. Unfortunately type sharing between DataContract and XmlSerializer is not available, so you end up with duplicated types. Since it looks like you're probably using DC exclusively on the server, it might be enough just to force svcutil to stay in DC mode and not fall over to XmlSerializer, like so:

svcutil /serializer:DataContractSerializer ...