1. Ensure your servlet-class in the web.xml is pointing to the impl class of your interface.
<servlet-class>package.AbcImpl</servlet-class>
2. Make sure your impl class is declared as a webservice class with the following details:
import
javax.jws.WebService;...
@WebService(name = "AbcImpl", serviceName = "Abc", endpointInterface = <package>.Abc")
public class AbcImpl implements Abc{