On Weaving Aspects

Object-oriented software systems that are developed using aspect-oriented programming techniques consist of classes and aspects. Classes implement the primary functionality of an application, for example, managing stocks or calculating insurance rates. Aspects, on the other hand, capture technical concerns like persistence, failure handling, communication, or process synchronization. They are written in special aspect description languages [5]. Common to all aspect languages is that they cannot be processed by today's compilers for object-oriented programming languages. Until that changes, aspects have to be merged with classes before a compiler can take over to produce the executable program. The process of merging is called weaving; the tool required is named Aspect Weaver. There are two ways in which classes and aspects can be woven: static or dynamic. This paper examines both weaving techniques in more detail. Section 2 works out the advantages and disadvantages of static weaving and argues why dynamic weaving is preferable for some aspects. Section 3 presents an Aspect Weaver that weaves aspects dynamically. The paper concludes with an evaluation of this Weaver.