====== Providing Support for Extracting Concerns towards JAsCo Artifacts in the Concern Manipulation Environment ======

**Type:** Apprenticeship and Thesis

**Assistant(s):** [[SSELMember>wvdperre|Wim Vanderperren]], [[SSELMember>dsuvee|Davy Suvee]]\\
**Supervisor:** [[SSELMember>VivianeJonckers|Viviane Jonckers]]

Part of [[thesis0405:overview|Thesis and/or Apprenticeship Projects 2004-2005]]

===== Student(s) =====

{{thesis0405:kbernole.jpg}}\\
Karel Bernolet\\
**Program:** Licentiaat Toegepaste Informatica\\
**E-mail:** <kbernole@vub.ac.be>

===== Apprenticeship =====
==== Description ====
The purpose of the apprenticeship is to support the extraction of concerns in the CME ((Concern Manipulation Environment: http://www.eclipse.org/cme)) towards JAsCo ((Java Aspect Components: http://ssel.vub.ac.be/jasco)).\\
Since the CME itself has no support yet for extraction, the main goal is to provide a framework to extract concerns. The CME will be used to identify and encapsulate a concern. Those concerns will be extracted towards JAsCo artifacts.\\
Len Feremans, an other student, provides [[thesis0405:aop2a|support for JAsCo artifacts]] within the CME.\\

==== Current Status ====

|                     ^ Subject                      ^ Detailed Work ^
^begin October        | JAsCo plugin for Eclipse 3.0 | porting the Eclipse 2.1 plugin to Eclipse 3.0\\ purpose is to gain experience with the Eclipse API's||
^middle of October    | Literature                   | reading information about the CME and JAsCo||
^end of October       | Exploring the CME            | playing around with the tools and looking to the finished code||
^middle of November   | Developping the Tool         | exploring the internal CME objects algorithmically||
^end of November      |                              | adapting the existing JascoCodeGenerator from the \\eclipse plugin||
^begin of December    |                              | resolving unresolved variablis in the aspect originated \\ by the refactoring||
^middle of December   |                              | physically manipulating the original code: \\ generating getMethods\\removing the crosscutting concern\\moving certain variables to the aspect||
^end of December      |The apprenticeship is finished.| writing the [[http://wilma.vub.ac.be/~kbernole/stage/documents/stageverslag.pdf| report]] ||

==== Result ====

=== Scenario ===
Here a simple scenario is demonstrated:
  * We start with a regular java class containg a crosscutting concern.
<code java>
package stock;
import logging.Logger;
public class Stock {
        public int counter;

        public Stock(int begin) {
                counter = begin;
        }

        public void add(int num) {
                counter += num;
                Logger.log("added " + num + counter);
        }

        public void remove(int num) {
                counter -= num;
                Logger.log("removed " + num + counter);
        }

        public int getStock() {
                int tmptmp = 3;
                int tmp = 20 + tmptmp;
                Logger.log("tmp var is:" + tmp+
                        " requested counter is: "+counter);
                return counter;
        }
}
</code>

  * The CME query engine is used to identify all artifacts of the concern:

{{http://wilma.vub.ac.be/~kbernole/stage/screenshots/query.png?800}}

  * and to construct the concern:

{{http://wilma.vub.ac.be/~kbernole/stage/screenshots/concern.png?400}}

  * the context menu of the concern is expanded with an option to extract the concern to JasCo artifacts:

{{http://wilma.vub.ac.be/~kbernole/stage/screenshots/jasco.png?400}}

  * next a wizard pops up, allowing the developper to name the aspect, connector and a prefix of the generated hooks:

{{http://wilma.vub.ac.be/~kbernole/stage/screenshots/wizard.png?500}}

  * the result of the refactoring is the same old class without the crosscutting concern:
<code java>
package stock;
import logging.Logger;
public class Stock {
        public int counter;
        public Stock(int begin) {
                counter = begin;
        }
        public void add(int num) {
                counter += num;
        }
        public void remove(int num) {
                counter -= num;
        }
        public int getStock() {
                return counter;
        }
        public int getCounter() {
                return counter;
        }
}
</code>

  * a connector describing where the aspect has to be applied:

<code java>
static connector LogConnector {
  LogAspect.LogHook0 hook0 =
    new LogAspect.LogHook0(int stock.Stock.getStock());
  LogAspect.LogHook1 hook1 =
    new LogAspect.LogHook1(void stock.Stock.remove(int));
  LogAspect.LogHook2 hook2 =
    new LogAspect.LogHook2(void stock.Stock.add(int));

  hook0.after();
  hook1.after();
  hook2.after();
}
</code>

  * and the aspect itself:

<code java>
package aspects;
class LogAspect {

  hook LogHook0 {
    LogHook0(method(..args)) {
      execute(method);
    }
    after() {
      int tmptmp = 3;
      int tmp = 20 + tmptmp;
      Logger.log(
        "tmp var is:"
          + tmp
          + " requested calledobject.getCounter() is: "
          + calledobject.getCounter());
    }
  }
  hook LogHook1 {
    LogHook1(method(..args)) {
      execute(method);
    }
    after() {
      Logger.log(
        "removed " + arg[0] + calledobject.getCounter());
    }
  }
  hook LogHook2 {
    LogHook2(method(..args)) {
      execute(method);
    }
    after() {
      Logger().log(
        "added " + arg[0] + calledobject.getCounter());
    }
  }
}
</code>

=== shortcomings ===

  * since the CME query engine only supports artifacts of 1 line, this system is limited to 1 line concerns as well
  * at the moment only method calls are supported as an artifact
  * the system only generates after() advices no matter where the concern is situated in the original code
  * when a variable is and needed in the advice and needed in the original code, the system causes code duplication

===== Dissertation =====
==== Description ====
//Not yet available//
==== Current Status ====
//Not yet available//

===== Presentations or other documents =====

  * [[http://wilma.vub.ac.be/~kbernole/stage/documents/stage2.pdf|Intermediate Presentation]]
  * [[http://wilma.vub.ac.be/~kbernole/stage/documents/stageverslag.pdf|Apprenticeship Report]]
  * [[http://wilma.vub.ac.be/~kbernole/stage/documents/verdediging.pdf|Apprenticeship Presentation]]

===== Links =====

  * [[SSELSite>./Thesis/2004-2005/JAsCoCME.html|Original proposal]] (in Dutch)
  * [[http://www.research.ibm.com/cme/|Concern Manipulation Environment]]
  * [[SSELSec>jasco|JAsCo: An Aspect-Oriented approach tailored for Component Based Software Development]]