Aspect oriented implementation of design patterns using metadata

Computer programming paradigms aim to provide better separation of concerns. Aspect oriented programming extends object oriented programming by managing crosscutting concerns using aspects. Two of the most important critics of aspect oriented programming are the “tyranny of the dominant signature” and lack of visibility of program's flow. Metadata, in form of Java annotations, is a solution to both problems. Design patterns are assumed as the general solutions for Object-Oriented matters. They assist in software complexity management and serve as a bridge among software designers as well. These properties have led the patterns to be introduced as a choice in order to prove new technologies. Successful implementations share a generic solution: the usage of annotation to configure and mark the participants, while the pattern's code is encapsulated in aspects. This loses the coupling between aspects and type signatures and between the code base and a specific AOP framework. Also, it increases the developer's awareness of the program's flow. In the present article, aspect oriented programming and design patterns are introduced and also taking the benefit of annotation equipment in java language is proposed as a solution to reduce tight coupling and increase program flow observation rate for aspect oriented programming. Keywords: aspect oriented programming, design patterns, object oriented programming, metadata

Design patterns and pspects : modular designs with seamless run-time integration

Some solutions proposed in the original design pattern literature were shaped by techniques as well as language deficiencies from object-oriented software development. However, new modularity constructs, composition and transformation mechanisms offered by aspect-oriented programming address deficiencies of object-oriented modeling. This suggests classical design pattern solutions to be revisited. In our paper we point out that aspect-oriented programming not only allows for alternative representations of proposed solutions, but also for better solutions in the first place. We advocate a native aspect-oriented approach to design patterns that emphasizes on improving design pattern solutions both during development and at run-time. We use a simple yet effective method to analyze and describe different solutions on the basis of variation points, fixed parts, variable parts, and optional glue, employing dynamic run-time weaving

Exploring design patterns with the Java programming language

This project describes and discusses the concepts of design patterns giving a historical background as well as citing contributions to the software development field and current research efforts. In addition, the advantages and disadvantages of using design patterns and efforts to encourage design pattern usage in software organizations are discussed. Seven design patterns (Builder, Adapter, Composite, Template Method, Facade, Mediator and Strategy) were chosen as the basis for example concrete applications. The concrete applications are given in the form of design documentation, source code and executable software. The applications demonstrate the use of design patterns in developing object oriented software applications. The applications are implemented in the Java programming language. The Java programming language was used because it is a popular object oriented programming language. An aspect of its popularity comes from its ability to execute with Java enabled browsers on a variety of computing platforms. Noted researchers in the area of design patterns assert that design patterns are language independent, however, much of the implementation in the area of design patterns has been written in the C++ language. The contribution of this project lies in implementing selected design patterns in Java and noting experiences that support or refute the conjecture that design patterns are language independent

Expression and Composition of Design Patterns with AspectJ

National audienceDesign patterns are well-known couples of problems-solutions for software engineer- ing. By nature, they often lack support from languages and this further complicates the study of their composition in the code. Aspect-oriented languages provide new mechanisms for modula- rization, which can help to improve design patterns implementation. (Hannemann et al., 2002) is the first extensive study of patterns aspectization with AspectJ. We notice some AspectJ idioms are needed in order to implement object relationships. We give a more reusable VISITOR pat- tern. We highlight a reusable composition of COMPOSITE and VISITOR patterns and expressive interactions of the OBSERVER pattern with a tree structure. We thus show that modularization by aspects helps composition of design patterns

An Aspect Refactoring Tool for The Observer Pattern

Current integrated development environments such as Eclipse provide strong support for object- oriented automatic refactorings; however, the same cannot be said about aspect-oriented refactor- ings. Refactoring of design patterns is one area where aspect refactoring automation remains to be explored in depth and few current tools are available to support it. To support aspect refactoring tools we present the AJRefactor plug-in, a semi-automatic refactoring tool for the observer pattern, a widely-used solution in the design of object-oriented programs. Aspect refactoring of the observer pattern allows aspects to capture pattern-specific code into a more modularized unit, and local- izes the code of participating classes. After applying AJRefactor on two Java projects JHotDraw and Prevayler, the results showed that AJRefactor was able to refactor 75% of the total observer instances found in both projects. Also, the refactoring enhanced the modularity and loosens the coupling of the pattern classes. Finally, the results showed a significant time savings and a small reduction in code size when refactoring with AJRefactor

Aspect-oriented interaction in multi-organisational web-based systems

Separation of concerns has been presented as a promising tool to tackle the design of complex systems in which cross-cutting properties that do not fit into the scope of a class must be satisfied. Unfortunately, current proposals assume that objects interact by means of object-oriented method calls, which implies that they embed interactions with others into their functional code. This makes them dependent on this interaction model, and makes it difficult to reuse them in a context in which another interaction model is more suited, e.g., tuple spaces, multiparty meetings, ports, and so forth. In this paper, we show that functionality can be described separately from the interaction model used, which helps enhance reusability of functional code and coordination patterns. Our proposal is innovative in that it is the first that achieves a clear separation between functionality and interaction in an aspect-oriented manner. In order to show that it is feasible, we adapted the multiparty interaction model to the context of multiorganisational web-based systems and developed a class framework to build business objects whose performance rates comparably to handmade implementations; the development time, however, decreases significantly.Comisión Interministerial de Ciencia y Tecnología TIC2000-1106-C02-0