How to Achieve Operational Overloading in WCF

Thursday Feb 7th 2008 by Dinesh Tawar
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Learn how to achieve operational overloading in WCF.

Service-Side Operational Overloading

In WCF, operational overloading is not acceptable. It has a different way of implementing operational overloading. Consider the following piece of code.

[ServiceContract]
interface InterfaceName
{
   [OperationContract]
   int MethodName (int paramName1, int ParamName2);

   [OperationContract]
   double MethodName (double paramName1,double ParamName2);
}

This code will throw InvaildOperationException.

You can use operational overloading with the help of the Name property of the OperationContract attribute to alias the operation. On the server and client sides, use the same name for the overloaded operations. Consider the following example:

[ServiceContract]
interface IInterfaceName
{
   [OperationContract (Name = "aliasName1")]
   int MethodName (int param1, int param2);

   [OperationContract (Name = "aliasName2")]
   double MethodName (double param1, double param1);
}

This code is used for service-side operation overloading. When you generate the proxy, the operation will have the same name that you used as the alias. You can find these methods with Names such as "aliasName1" or "aliasName2" on the proxy. Consider the following example.

// for MethodName which returns the integer value.
proxyobject.aliasName1 (1, 1)
// for MethodName which returns the double value.
proxyobject. aliasName2 (1.2, 2.1)

It seems the problem arises because a developer may get confused about these function names. That's why you need to perform the same thing on the client side.

If you need to overcome the problem, you need to use the same name property on the client side also, with the same imported operation names.

[ServiceContract]
interface IInterfaceName
{
   [OperationContract (Name = "aliasName1")]
   int MethodName (int param1, int param2);

   [OperationContract (Name = "aliasName2")]
   double MethodName (double param1, double param1);
}

public partial class Client : ClientBase< IInterfaceName >,
   IInterfaceName
{
   public int MethodName (int arg1, int arg2)
   {
      return Channel. MethodName (arg1, arg2);
   }
   public double MethodName (double arg, double arg2)
   {
      return Channel. MethodName (arg1, arg2);
   }
}

Now, on the client side you can create an object and use the benefits of operational overloading.

Client proxy = new Client ( );

int result1    = proxy. MethodName (1, 2);
double result2 = proxy. MethodName (1.0, 2.0);

Reference

Programming WCF Services by Juval Lowy. Published by O'Reilly. ISBN: 0596526997

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