ASPECT ORIENTED PROGRAMMING:AN EVOLUTIONARY BREAKTHROUGH

摘要

This technical paper addresses the problems with crosscutting concerns,rnthe current ways to implement them, and their shortcomings. We alsornexamine how AOP i.e. Aspect Oriented Programming helps overcomernthose problems. AOP methodology seeks to modularize crosscuttingrnconcern implementations, and it produces a better and faster softwarernimplementation. Thus we go over explaining crossscutting concerns in anyrneven moderately complex software system. There are issues or concernsrnthat are not well captured by traditional programming methodologies .rnCapturing concerns like a security policy in a disciplined way isrndifficult and error-prone in a traditional programming language .Concernsrnlike security cut across the natural units of modularity. For object-orientedrnprogramming languages, the natural unit of modularity is the class. But inrnobject-oriented programming languages, crosscutting concerns are notrneasily turned into classes precisely because they cut across classes, and sornthese aren't reusable, they can't be refined or inherited, they are spreadrnthrough out the program in an undisciplined way, so ,they are difficult tornwork with . Aspect-oriented programming is a way of modularizingrncrosscutting concerns much like object-oriented programming is a way ofrnmodularizing common concerns. AspectJ is an implementation of aspectorientedrnprogramming for Java.rnAspectJ is a free AOP implementation for Java,a concept proposed inrncreating software systems that are easier to understand, implement, andrnevolve. AspectJ, a freely available AOP implementation for Java, is arngeneral-purpose aspect-oriented Java extension. AspectJ uses Java as thernlanguage for implementing individual concerns, and it specifies extensionsrnto Java for weaving rules. These rules are specified in terms of pointcuts,rnjoin points, advice, and aspects Join points define specific points in arnprogram's execution, a pointcut is the language construct that specifies joinrnpoints, advice defines pieces of an aspect implementation to be executed atrnpointcuts, and an aspect combines these primitives.