Question

I am trying to create a WCF Streaming Service. I have two requirements that I seem to be stumbling over trying to get this to work:

• Length of stream size
• Input parameters

My message contract looks like this:

[MessageContract]
public class MyStream
{
 [MessageHeader]
 public long StreamSize;

 [MessageBodyMember]
 public Stream StreamData;
}  

My operation contract looks like this:

[ServiceContract]
public interface IStreamService
{
     [OperationContract]
     MyStream GetData(string data);
}

The error message I receive when trying to use the web service is this:

The operation ‘GetData’ could not be
loaded because it has a parameter or
return type of type
System.ServiceModel.Channels.Message
or a type that has
MessageContractAttribute and other
parameters of different types. When
using
System.ServiceModel.Channels.Message
or types with
MessageContractAttribute, the method
must not use any other types of
parameters.

From my understanding of this post, I need to use a message contract to get the length of my stream, but when I switch from a data contract to a message contract I am no longer allowed to pass in input parameters.

Is there a configuration change I’m missing? Or something else I can try? Thanks!

Answer 1

You also have to create MessageContract for request.

[MessageContract]
public class GetDataRequest
{
  [MessageBodyMember(Name="data")]
  public string Data { get; set; }
}

Then you define your operation as follows:

[OperationContract]
MyStream GetData(GetDataRequest request);