Distribution Concern Implementation

This transformation generates aspects to implement the distribution concern. We used RMI to achieve it, but it would be possible to use other distribution technology, such as EJB. This transformation follows the guideline proposed by Soares (2002) .
To apply this refactoring, the source project should implement the Façade design pattern. The generated code creates a remote instance of the façade and redirects method calls from local one. AJaTS also creates other auxiliary classes (AbstractClientSideAspect, AbstractServerSideAspect), as well as an interface that extends RMI's Remote interface.

Left Template

Right Template - Client Side Aspect

Right Template - Server Side Aspect

Source example

Transformed code - Client Side Aspect

public class BankFacade {

AccountRecord accounts;

   public BankFacade(){
      this.accounts = new AccountRecord();
   }

   public void insertAccount(Account account){
      this.accounts.insert(account);
   }
}

import cin.aspects.framework.distribution.AbstractClientSideAspect;
import cin.aspects.framework.updateState.UpdateStateControl;
import javax.servlet.http.HttpServlet ;
import org.aspectj.lang.SoftException;

public aspect FacadeClientSideAspect extends AbstractClientSideAspect {

   private IRemoteFacade facade;

   void setRemoteFacade( IRemoteFacade remote) {
      facade = remote;
   }

   public Object getRemoteFacade() {
      prepareFacade();
      return facade;
   }

   private synchronized void prepareFacade() {
      if(facade == null) {
      try {
        System.out.println("About to lookup...");
        facade = (IRemoteFacade)java.rmi.Naming.lookup("//" +        FacadeServerSideAspect.RMI_SERVER_NAME + "/" +   FacadeServerSideAspect.SYSTEM_NAME);
        System.out.println("Remote #FACADE found");
      }
      catch(Throwable ex){
        throw new SoftException(ex);
      }
   }

   pointcut facadeCallers () : this (HttpServlet) || within (UpdateStateControl) ;
   pointcut facadeCalls () : call (* IRemoteFacade+.* (..)) && !call (static * IRemoteFacade+.* (..)) ;
   pointcut facadeLocalCalls () : facadeCallers() && facadeCalls();

   Object around () : facadeCallers() && call (*    FacadeServerSideAspect.getInstance ()) {
      return null;
   }

}