Sending Soap Header from WCF service

Question

Hello,

I do migration from ASP.NET web service to WCF. Current code is like this:

Server Side

public class MyType
{
   public int x;
   public string s;
}
public class MyService : WebService
{
    public MyType myObj;

    [WebMethod]
    [SoapHeader("myObj", Direction=SoapHeaderDirection.InOut)]
    public string SomeMethod() // NO Parameter!!!
    {
        if (myObj.x > 5)
           return myObj.s;
        else
           return "Less than 5";    
    }
}

Client Side

MyService service = new MyService();
MyType m = new MyType();
m.x = 10;
m.s = "That's it!!!";
service.myObj = m;
string s = service.SomeMethod();

This works smoothly. Now I need to change this to WCF. Found many topics about how to sign soapheader with WCF, but all are about how to use [MessageContract] as an attribute of a class which will be given to the operation as a parameter. Like this:

[MessageContract]
public class MyType
{
   public int x;
   public string s;
}

[OperationContract]
public string SomeMethod(MyType myType)
{
//
}

But this is not what I need, my method must remain the same (with no parameter).

Please help me with this.

Thank you,

-Aram