Hybrid Aspects in JAsCo for Integrating Java and Jess

Type: Thesis

Assistant(s): Maja D'Hondt
Supervisor: Viviane Jonckers

Part of Thesis and/or Apprenticeship Projects 2004-2005

Xuelian Bian
Program: Master in Applied Computer Science
E-mail: xbian@vub.ac.be

The state of art in software engineering uses object-oriented programming languages for implementing the core functionality of the applications. But current software engineering practices result in software applications containing implicit knowledge about the domain or the business that is tangled with the core functionality. And this has many disadvantages. This implicit knowledge should be made explicit and separated from the object-oriented core functionality. Rule-based languages are able to represent and reason about one type of knowledge, more specifically rule-based knowledge.

There exist many hybrid systems which integrate a full-fledged rule-based language with a state-of-the-art OOP language. However, we observe that the integration of the two languages has limitations. Moreover, we note that rules and objects crosscut one another.

A solution has been proposed in [1]: using aspect-oriented programming for supporting the integration in hybrid systems. Aspect-oriented programming enables encapsulating the integration between rule-based knowledge and OO functionality in hybrid systems which results in loose coupling. Most existing aspect-oriented approaches use OOL as the base language and address the program integration issues in a purely object-oriented development context. Hence, hybrid aspects have been introduced in [1], which consider rule-based base languages in addition to object-oriented base languages. Hybrid aspects are able to absorb the paradigmatic differences that cause problems when integrating rule-based and object-oriented languages.
In this thesis a previously unexplored instance of hybrid aspects will be developed. Java will be used as the object-oriented base language and Jess [2] - the Java Expert System Shell - is going to be the rule-based base language. Therefore, hybrid aspects for these base languages will have to be devised. As a starting point, JAsCo [3] is going to be employed, an aspect-oriented programming language for Java. Jess already is integrated with Java, which will be exploited in this thesis. Hybrid JAsCo will add aspect-oriented capabilities to the integration and absorb the paradigmatic differences between Java and Jess.

• [1] M. D'Hondt, “Hybrid Aspects for Integrating Rule-based knowledge and Object-oriented Functionality”, PhD Thesis, Vrije Universiteit Brussel, May 2004.
• [2] Ernest Friedman-Hill, “Jess in Action”, Manning, July 2003.
• [3] M. A. Cibrán, M. D'Hondt, D. Suvée, W. Vanderperren and V. Jonckers, “JAsCo for Linking Business Rules to Object-Oriented Software”, In Proceedings CSITeA, Rio de Janeiro, Brazil, 2003.

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• JAsCo: An Aspect-Oriented approach tailored for Component Based Software Development
• Jess, the Rule Engine for the Java Platform