EJB service interface compatibility in practice

Question

Let's imagine there is this remote interface that is used to communicate between two Java EE 7 applications.

public interface BusinessService {

    void hello(String name);

    String echo(String echoValue);    
}

Now for some reason the server JEE 7 application gets redeployed with a new and incompatible version of that interface since the method echo has been removed and the client side still relies on the former version of BusinessService.

public interface BusinessService {

    void hello(String name);

    // no more echoing    
}

Will the client still be able to perform a remote call to BusinessService#hello as long it never calls BusinessService#echo?

Answer 1

Short answer - YES.

This would be a compatible change, if the client does not use this method. Otherwise, there will be an error on the client side:

javax.ejb.EJBException: No such method echo(java.lang.String) on EJB...