Gregor Kiczales

Aspect-oriented programming

No abstract available

An Overview of AspectJ

Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJs dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

Design pattern implementation in Java and aspectJ

AspectJ implementations of the GoF design patterns show modularity improvements in 17 of 23 cases. These improvements are manifested in terms of better code locality, reusability, composability, and (un)pluggability.The degree of improvement in implementation modularity varies, with the greatest improvement coming when the pattern solution structure involves crosscutting of some form, including one object playing multiple roles, many objects playing one role, or an object playing roles in multiple pattern instances.

Getting started with ASPECTJ

Many software developers are attracted to the idea of AOP, but unsure about how to begin using the technology. They recognize the concept of crosscutting concerns, and know that they have had problems with the implementation of such concerns in the past. But there are many questions about how to adopt AOP into the development process. Common questions include: Can I use aspects in my existing code? What kinds of benefits can I expect to get? How do I find aspects? How steep is the learning curve for AOP? What are the risks of using this new technology?

Aspect-oriented programming and modular reasoning

Aspects cut new interfaces through the primary decomposition of a system. This implies that in the presence of aspects, the complete interface of a module can only be determined once the complete configuration of modules in the system is known. While this may seem anti-modular, it is an inherent property of crosscutting concerns, and using aspect-oriented programming enables modular reasoning in the presence of such concerns.

A semantics for advice and dynamic join points in aspect-oriented programming

A characteristic of aspect-oriented programming, as embodied in Aspect J, is the use of advice and point cuts to define behavior that crosscuts the structure of the rest of the code. The events during execution at which advice may execute are called join points. A pointcut is a set of join points. An advice is an action to be taken at the join points in a particular pointcut. In this model of aspect-oriented programming, join points are dynamic in that they refer to events during the flow of execution of the program.We give a denotational semantics for a minilanguage that embodies the key features of dynamic join points, pointcuts, and advice. This is the first semantics for aspect-oriented programming that handles dynamic join points and recursive procedures. It is intended as a baseline semantics against which future correctness results may be measured.

Beyond the black box: open implementation

Encapsulation, informally known as black-box abstraction, is a widely known and accepted principle. It is a basic tenet of software design, underlying approaches to portability and reuse. However, many practitioners find themselves violating it in order to achieve performance requirements in a practical manner. The gap between theory and practice must be filled. Open implementation is a controversial new approach that claims to do just that. The paper provides some ideas to spark further debate on black-box abstraction.

Using aspectC to improve the modularity of path-specific customization in operating system code

Layered architecture in operating system code is often compromised by execution path-specific customizations such as prefetching, page replacement and scheduling strategies. Path-specific customizations are difficult to modularize in a layered architecture because they involve dynamic context passing and layer violations. Effectively they are vertically integrated slices through the layers. An initial experiment using an aspect-oriented programming language to refactor prefetching in the FreeBSD operating system kernal shows significant benefits, including easy (un)pluggability of prefetching modes, independent development of prefetching modes, and overall improved comprehensibility.

Discussing aspects of AOP

Aspect-oriented programming is a new evolution in the line of technology for separation of concerns technology that allows design and code to be structured to reflect the way developers want to think about the system. AOP builds on existing technologies and provides additional mechanisms that make it possible to affect the implementation of systems in a crosscutting way.Aspect-oriented programming is a new evolution in the line of technology for separation of concerns technology that allows design and code to be structured to reflect the way developers want to think about the system. AOP builds on existing technologies and provides additional mechanisms that make it possible to affect the implementation of systems in a crosscutting way.

Modeling Crosscutting in Aspect-Oriented Mechanisms

Modeling four aspect-oriented programming mechanisms shows the way in which each supports modular crosscutting. Comparing the models produces a clear three part characterization of what is required to support crosscutting structure: a common frame of reference that two (or more) programs can use to connect with each other and each provide their semantic contribution.