How WCF Method Overloading Works

Let's first define overloading so that we may better comprehend this topic.

      The process of implementing polymorphism in object-oriented programming is known as method overloading. There is no requirement that the parameters in two methods be of the same type; a method can be overloaded based on the type, quantity, and order of its parameters.

Many of us believe that WCF supports method overloading because C# does. No, in actuality. Why? 

Consider the following example:

[ServiceContract]  

public interface IMyService 

{

  [OperationContract] 

  ExampleData[] GetExampleData(string Code);

  [OperationContract]

  ExampleData[] GetExampleData(string Code, DateTime date);

 }

Now that you have implemented this interface and hosted it as a WCF service, it will fail with a contract mismatch error since the WSDL forbids the creation of duplicate client methods.

We can now review the definition.  There are two ways in the interface.  The methods have the same name, but because the parameters vary, a perfect overloading notion, their signatures are distinct.  However, the compiler is not particularly knowledgeable about the properties.  It will merely output their data in the metadata for the assembly.

WCF just queries the metadata to produce a WSDL contract when it tries to start the service.  Technology-neutral, message-based communication is the main focus of WSDL.  It does not support object-oriented ideas like overloading and inheritance.  Therefore, even though the code built without any errors, WCF simply recognizes that there are two methods with the same name and raises an exception to signal this isn't allowed. 

This is a WSDL restriction. Method names on services must be distinct because it does not allow the same overloading notions as C#. There are two options for fixing this issue.

Use unique names for your methods as a start. If there are only two ways, the alternative is to put the Name attribute on one of your OperationContracts. See the code below.

1)

[ServiceContract]  

public interface IMyService 

{ 

  [OperationContract(Name="GetExampleDataByCode")] 

   ExampleData[] GetExampleData(string Code);

   [OperationContract] ExampleData[]

   GetExampleData(string Code, DateTime date);

 }

2)




[ServiceContract]  

public interface IMyService 

{ 

   [OperationContract(Name="GetExampleDataByCode")] 

   ExampleData[] GetExampleData(string Code);

   [OperationContract(Name="GetExampleDataByCodeAndDate")] 

   ExampleData[] GetExampleData(string Code, DateTime date); 

}

Now, when you run the programme, the output ought to be error-free. Overloading is therefore different from writing code for regular classes, and it is possible to do it for WCF services by leveraging the Name element of the OperationContract.

Whether this method will show up as two different names or as a method with the same name but more than one overload? 

This will depend on the client's chosen proxy class.  The alias method names will be utilised if you use the proxy class that is automatically generated by svcutility.exe.  To manually achieve the appearance of overloaded methods on the client, you can manually alter the resulting proxy class.  Applying the same attributes to the methods specified in the interface that the proxy class uses will do this.

Client.GetExampleDataByCode Client.GetExampleDataByCodeAndDate like this method will show up.