aspect oriented software development

Aspect Oriented Software Aspect Oriented Software DevelopmentDevelopment

By:

Maryam Malekzad

M.Tech II 11301

AOSD Maryam Malekzad M.Tech. 11301 PUCSD 2

Birth of AOSD ;)Birth of AOSD ;)AOSDAOSD describes a number of approaches to software

modularization and composition including, in order of publication:

reflection and metaobject protocols, Composition Filters, developed at the University of Twente in the University of Twente in the NetherlandsNetherlands,

SubjectOriented Programming (later extended as Multidimensional Separation of Concerns) at IBMIBM

Feature Oriented Programming at University of Texas University of Texas at Austinat Austin


Birth of AOSD continue Birth of AOSD continue

Adaptive Programming at Northeastern University, Northeastern University, USAUSA

and AspectOriented Programming (AOP) at Palo Palo Alto Research Center.Alto Research Center.

The term aspectorientedaspectoriented was introduced by was introduced by Gregor Kiczales Gregor Kiczales and his team at Palo Alto Research Center


What is the main Idea?What is the main Idea?Aspectoriented software development (AOSD):Aspectoriented software development (AOSD):

is an emerging software development technology that seeks

new modularizations of software systems in order to isolate secondary or supporting functions from the main program's business

logic.

AOSD allows multiple concerns to be expressed separately and automatically unified into working systems.


AOSD's target?AOSD's target?

AspectOriented Software DevelopmentAspectOriented Software Development focuses on

the identification, specification and representation of crosscutting concerns and their modularization into separate functional

units as well as their automated composition into a

working system.


AOSD's target? continue AOSD's target? continue

The focus of AspectOriented Software Development (AOSD) is in the investigation and implementation of new structures for software modularitysoftware modularity that provide support for explicit abstractions to modularize concerns.


What is ”Aspect” ?What is ”Aspect” ? (1)(1) An aspect is a module that encapsulates a concern. An aspect is composed of pointcuts, advice bodies

and intertype declarations. In some approaches, and aspect may also contain

classes and methods. Intertype declarations allow the programmer to

modify a program's static structure, such as class members and classes hierarchy. New members can be inserted and classes can be pushed down the class hierarchy.


What is ”Aspect” ? What is ”Aspect” ? (2)(2)

An aspect is a common feature that's typically scattered across methods, classes, object hierarchies, or even entire object models. It is behavior that looks and smells like it should have structure, but you can't find a way to express this structure in code with traditional objectoriented techniques.


What is ”Pointcut” ?What is ”Pointcut” ?

In aspectoriented computer programming:aspectoriented computer programming: a pointcut is a set of join points.

Whenever the program execution reaches one of the join points described in the pointcut, a piece of code associated with the pointcut (called advice) is executed.

This allows a programmer to describe where and when additional code should be executed in addition to an already defined behavior.


What is ”Pointcut” ? continue What is ”Pointcut” ? continue

Pointcut Pointcut permits the addition of aspects to existing software, or the design of software with a clear separation of concerns, wherein the programmer weaves (merges) different aspects into a complete application.


AOP ?!AOP ?!

Aspectoriented programming (AOP)Aspectoriented programming (AOP) is a programming paradigm that aims to:

increase modularity by allowing the separation of crosscutting

concerns. AOP forms a basis for aspectoriented software

development.


Crosscutting Concerns Vs. Core ConcernCrosscutting Concerns Vs. Core Concerncrosscutting concernscrosscutting concerns are :

aspects of a program that affect other concerns.

These concerns often cannot be cleanly decomposed from the rest of the

system in both the design and implementation, and

can result in either scattering (code duplication), tangling (significant dependencies between systems), or both.


The implementation of a concern is scatteredscattered if its code is spread out over multiple modules. The concern affects the implementation of multiple modules. Its implementation is not modular.

The implementation of a concern is tangledtangled if its code is intermixed with code that implements other concerns. The module in which tangling occurs is not cohesive.

Scattering and tangling often go together, even though they are different concepts.

Do you know ?Do you know ?


What is ”Concern” ?What is ”Concern” ?a concernconcern :

is a particular set of information that has an effect on the code of a computer program.

It can be as general as the details of database interaction or

as specific as performing a primitive calculation, depending on the level of conversation between

developers and the program being discussed.


AO Requirement EngineeringAO Requirement Engineering"Early Aspects""Early Aspects" focuses on the

identification, specification and representation of crosscutting properties at the requirement level.

Examples of such properties include: security, mobility, availability and realtime

constraints.

Crosscutting properties are: requirements, use cases or features that have a

broadly scoped effect on other requirements or architecture components.


AO System ArchitectureAO System Architecture focuses on the localization and specification of

crosscutting concerns in architectural designs. Crosscutting concerns that appear at the

architectural level cannot be modularized by redefining the software architecture using conventional architectural abstractions.

Aspectoriented system architecture languages propose explicit mechanisms to identify, specify and evaluate aspects at the architecture design level.


AO System ArchitectureAO System Architecture

Aspectoriented architecture starts from the observation that we need to identify, specify and evaluate aspects explicitly at the architecture design level.

Aspectual architecture approaches describe steps for identifying architectural aspects.


Specific Areas of Excellence are:Specific Areas of Excellence are:

the aspectoriented architecture process itself, the aspectoriented architecture notations, aspectoriented architecture tool support, adoption and integration of aspectoriented

architecture, and assessment/evaluation of aspectoriented

architecture.


Modeling and DesignModeling and Design It has the same objectives as any software design

activity, i.e. characterising and specifying the behavior and structure of the software system.

Its unique contribution to software design lies in the fact that concerns that are necessarily scattered and tangled in more traditional approaches can be modularized.

Typically, such an approach includes both a process and a language.


Aspectoriented languagesAspectoriented languages

AspectC++ AspectJ AspectLua (a Lua extension) CaesarJ Compose* ObjectTeams e (verification language)


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aspect oriented software development

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