Action Interface implemented by ActionSupport class

Optionally you can extend the ActionSupport class which implements six interfaces including Action interface. The Action interface is as follows:

public interface Action {
   public static final String SUCCESS = "success";
   public static final String NONE = "none";
   public static final String ERROR = "error";
   public static final String INPUT = "input";
   public static final String LOGIN = "login";
   public String execute() throws Exception;
}