Return Serializable object from FileStream?

I'm a little green when it comes to streaming and serialization...but what I want to do is make the Upload method on the server return a serializable object to the client (it is void right now).

I have a public class ServiceResult that I decorate with [Serializable], and a public class FileTransferService that implements IFileTransferService

[ServiceContract()]
public interface IFileTransferService
{
    [OperationContract(IsOneWay = false)]
    string Upload(FileTransferRequest request);
开发者_如何转开发}

The implementation does its thing, and then at the end I create and serialize the object and try to return the string

return ServiceResultSerializer.SerializeAnObject(result);

On the client side I call this service using this class

[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "3.0.0.0")]
[System.ServiceModel.ServiceContractAttribute(ConfigurationName = "IFileTransferService")]
public interface IFileTransferService
{

    // CODEGEN: Generating message contract since the wrapper name (FileTransferRequest) of message FileTransferRequest does not match the default value (Upload)
    [System.ServiceModel.OperationContractAttribute(IsOneWay = false, Action = "http://tempuri.org/IFileTransferService/Upload")]
    string Upload(FileTransferRequest request);
}

I'm basically taking this project found on this blog: http://weblogs.asp.net/cibrax/archive/2007/08/29/sending-attachments-with-wcf.aspx

And trying to make it return a value that the client caller can use

I get an error right now that says:

The operation 'Upload' 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.

Which i have no idea what it means :P I think because I'm trying to change the Service parameters.

Sorry if I'm being too general - any help would be greatly appreciated.

---

It sounds to me like your FileTransferRequest class has MessageContractAttribute applied to it.

Since your input parameter has MessageContractAttribute, your response type should also have MessageContractAttribute, which String doesn't. Try creating a FileTransferResponse class that has a single string-type property, and use that as your return type.