hessian, compatibility when server interface upgrade

Question

We are using hessian for java client server remoting. Now we need to change a interface to add a new field.

Is there any other way except to add a new interface.

the interface looks like

public void process(fieldA, fieldB)

we want to just to change the interface for adding a new field and add some logic to handle for backward compatibility like

public void process(fieldA, fieldB, fieldC){

if (StringUtils.isBlank(fieldC)){

   old logic

} else{

   new logic
}

Answer 1

Why can't you just add another method?

@Deprecated
public void process(fieldA, fieldB);

public void process(fieldA, fieldB, fieldC);

This should preserve backward compatibility.