Aspect Oriented Development Alex Beatty

 Purpose  Cross-cutting Concerns  Join Points, Pointcuts, and Advices  Weaving  Invasive vs. Non-Invasive  Static vs. Dynamic Introduction

 What is a cross-cutting concern?  Examples  Reduction of code tangling and code scattering  Abstraction  Obliviousness  Expert Development  Object Reuse Purpose

 Join Point - Point in the base code that aspect code can utilized  Examples  A method being called  A method’s code being run  Initialization Join Points

 User defined join point(s) to utilize aspect code with  AspectJ examples  execution(!static * (Class1 || ClassA).*(..));  call(void Set*(int));  Explanation Pointcuts

 Basically a function  before, after, and around key words  around has a special proceed() function  Has access to some information from base code  Function name, parameters, return type, return value Advice

 Static vs dynamic  Compile-time vs load- or run-time  Invasive vs non-invasive  Directly changing base code or not Weaving

 Logging  Coordination  Security  Mutual Exclusion Applications

Coordination Silent Single Bid Public English Style

 Confusion about it’s role  Anti-pattern: Action at a distance Downsides

 Java-based  Pointcuts  Can use logical operators  Can be named  Advices are formatted like java functions AspectJ

 pointcut functionExecution(): execution(!static * (Class1 || ClassA).*(..))  Name  Join point type  Join point specification AspectJ Pointcuts

 Name  Shorter than the pointcut itself  Can include parameters to capture access to an object  pointcut setter(Person p): target(p) && … AspectJ Pointcuts

 Methods and Constructors  call(Signature) / execution(Signature) AspectJ Pointcut Types //before call Person.walk(); //after call Private void walk() { //before execution //TODO: write function body //after execution }

 Fields  get(Signature) / set(Signature)  E.g. set(int Racer.*) AspectJ Pointcut Types private int id; … //before set id = 42; //after set

 Instanceof checks and context exposure  this(type or id) / target(type or id) / args(type or id)  E.g. args(newval), target(Racer)  Others  AspectJ Pointcut Types

void around(Racer r): criticalSection(r) { int i = (int) r.getId(); …proceed(); … }  thisJoinPoint  Can be used to get arguments, signature, target, etc  thisJoinPoint.getArgs(); AspectJ Advices

Example of Mutual Exclusion Aspect

Questions

 [1] Aspect-oriented software development. In Wikipedia. Retrieved October 20, 2013, from oriented_software_development   [2] Rohit Sethi. “Aspect-Oriented Programming and Security”. Retrieved October 28, 2013, from   [3] Fuentes, Lidia; Sánchez, Pablo. “Aspect-Oriented Coordination”. In Science Direct. Retrieved from   [4] Aspect Weaver. In Wikipedia. Retrieved October 28, 2013, from   [5] Piveta, Eduardo Kessler; Zancanella, Luiz Carlos. “Aspect Weaving Strategies”. In Journal of Universal Computer Science. Retrieved from   [6] The AspectJ Programming Guide. Retrieved October 28, 2013, from References