A.o. Univ. Prof. Dr. Dipl.-Ing. eva Kühn
TU Wien

Gerald Fessl

XL-AOF - design and implementation of an eXtensible lightweight aspect-oriented framework for distributed applications


Diploma Thesis, TU-Vienna, 2006


Space based computing is an efficient and useful approach to realize the distribution of software systems in a simple way. A framework is put at the software developer's disposal so he can gain access to an abstract data space called virtual shared memory which is shared among several machines but appears as if it were a local implementation of the software project.


Although this approach simplifies work and reduces costs and complexity of the problem of distributing systems, many new programming tasks and structures are necessary to achieve this goal, thus adding a certain amount of additional complexity to the implementer's job. Lots of cross cutting concerns - special requirements of the program that cannot be cleanly encapsulated into the source code - appear in different parts, thus reducing the maintainability and reusability of the software system and unnecessarily complicating and enlarging the source code.


The Aspect-Oriented Programming Paradigm (AOP) offers a solution for these scenarios: traditional programming technologies like Object-Oriented Programming (OOP) are extended by a new modularization mechanism for cross cutting concerns - aspects -, which are combined with traditional modules like classes by a so-called weaver to establish the full computer software which provides the entire desired functionality.


XL-AOF - extensible lightweight aspect-oriented framework - offers a lightweight and extensible framework based on the aspect-oriented paradigma without any need for neither a special compiler weaving the aspect programs with the business program at compile time nor a new virtual machine, an exhaustive configuration mechanism or the need to learn a new language to be able to integrate the desired functionality into the implemented software system. This framework is extensible with new modules in a simple way, whereas those modules need not be restricted on distributing concerns.


In this diploma thesis the demands which are made on this system as well as its design are worked out as well as its implementation is described. Furthermore some changes that have to be made to the traditional software development process to conform to the new paradigm are described using some currently popular methods and - using one of these methods - a specific virtual shared memory middleware is simplified.


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