Software ArchitectureModule Views and Styles

Inam Soomro

November 2011

Agenda • GENERALIZATION STYLE

– ELEMENTS, RELATION AND PROPERTIES– CONSTRAINSTS– WHY GENERALISATION STYLE– NOTATION

• LAYERED STYLE– ELEMENTS, RELATION AND PROPERTIES– CONSTRAINSTS– WHY LAYERED STYLE– LAYER TYPES– NOTATION

• ASPECTS STYLE– ELEMENTS, RELATION AND PROPERTIES– CONSTRAINSTS– WHY ASPECTS STYLE– NOTATION– BEFORE AND AFTER ASPECT ORIENTATION

GENERALIZATION STYLE

• Abstraction of common properties and attributes

• Employs “IS A“ relationship• Parent module is a more general version of

child modules• interface Realization • Architects emphasis on interface, not the

implementation

An Example of generalisation Style

Elements, Relation and Properties

• Element– Module

• Relation– Generalisation

• Constraints– A module can have multiple parents, bad design!– Loopholes are not allowed

Why Generalisation

• Expressing inheritance in OOD• Evolution and Extension• Support reuse• Capturing commonalities

Notation for Generalisation Style

• UML

Layered Style

• Reflects division of software into smaller units• Offers a cohesive set of services• unidirectional and • “allowed to use“• A System with uses relation from lower to

upper layer is not a layered architecture; however it may conveys an ideal design an architect was trying to achieve.

Example

What do u think of this design??

Elements, Relation and Properties

• Elements– Layer

• Relation– Allowed to use

• Constraints– Every piece of software is allocated only one layer– At least two layers– Lower layers cannot use the upper layers

Why Layered Style

• Modifiability and Portability• Managing complexity• Reuse• Seperation of concerns

Notation of Layered Style

• Stack

Segmented Layers

Rings

Layers with a Sidecar

UMLSegmented Layers

Example of Java EE Application

Aspects Style

• Aspects are modular units that complement objects to modularize the cross cutting concerns

ELEMENTS, RELATION AND PROPERTIES

• Elements– Aspect modules

• Relation– Crosscuts

• Properties– Pointcut– Advice

• Constrains

Why Aspects Style

• provide systematic means to modularize by allowing separation of crosscutting concerns

• promotes modularity• Address separation of concerns

Notation

• UML

Before and after Aspect Orientation

Problems with Traditional Object Orientation

After Aspect Orietation

Aspect Oriented Programming

• Facililitates in implementation of crosscutting concerns

• AspectJ , Spring AOP, Jboss AOP, AspectC++and Aspect#

The chapter is taken from the bookDocumenting Software Architectures: Views and BeyondBy: Paul Clements; Felix Bachmann; Len Bass; David Garlan; James Ivers; Reed Little; Robert Nord; Judith Stafford

Thanks!