Aspect Oriented Software Development

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Aspect Oriented Software Development

• By Mostafa El Barbary

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On July 20th 2008, our name has changed from
to
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Objectives

• To explain the principle of separation of
  concerns in software development
• To introduce the fundamental ideas underlying
  aspect-oriented development
• To show how an aspect-oriented approach can be
  used at all stages of development

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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Introduction

• A concern is an area of interest or focus in a
  system. Concerns are the primary criteria for
  decomposing software into smaller, more
  manageable and comprehensible parts that have
  meaning to a software engineer.
• Object-oriented programming, describing concerns
  as objects
• Procedural programming, describing concerns as
  procedures

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Introduction

• Separation of concerns (SOC) The principle of
  separation of concerns states that software
  should be organized so that each program element
  does one thing and one thing only.
• Each program element should therefore be
  understandable without reference to other
  elements.
• Object-oriented programming languages such as
  Java can separate concerns into objects.
• Service-oriented architecture can separate
  concerns into services.
• Procedural programming languages such as C and
  Pascal can separate concerns into procedures.

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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Problem Statement
void transfer(Account fromAccount, Account
toAccount, int amount) if
(fromAccount.getBalance() lt amount)
throw new InsufficientFundsException()
fromAccount.withdraw(amount)
toAccount.deposit(amount)
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Problem Statement
void transfer(Account fromAccount, Account
toAccount, int amount) throws Exception
if (!getCurrentUser().canPerform(OP_TRANSFER))
throw new SecurityException()
Transaction tx database.newTransaction()
try if (fromAccount.getBalance() lt
amount) throw new InsufficientFundsExc
eption() fromAccount.withdraw(amoun
t) toAccount.deposit(amount)
tx.commit() systemLog.logOperation(
OP_TRANSFER, fromAccount, toAccount, amount)
catch(Exception e)
tx.rollback() throw e
Authentication Concern
Transaction Concern
Transaction Concern
Logging Concern
Transaction Concern
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Problem Statement
Transfer Concern
Authentication Concern
Logging Concern
Transaction Concern
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Problem Statement
Banking System
Transfer Concern
Cash Deposit Concern
Authentication Concern
Authentication Concern
Logging Concern
Logging Concern
Transaction Concern
Transaction Concern
Cash Withdrawal Concern
Authentication Concern
Logging Concern
Transaction Concern
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Problem Statement

• Code is scattered when one concern (like logging)
  is spread over a number of modules (e.g.,
  Transfer method).
• Modules end up tangled with multiple concerns
  (e.g., Transfer, logging, and Authentication).

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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Aspect Solution

• AOSD attempts to solve this problem by allowing
  the programmer to express cross-cutting concerns
  (e.g., Transaction, logging, and Authentication)
  in stand-alone modules called aspects.
• Used in conjunction with other approaches -
  normally object-oriented software engineering.
• Aspects encapsulate functionality that cross-cuts
  and co-exists with other functionality.
• Aspects include a definition of where they should
  be included in a program as well as code
  implementing the cross-cutting concern.

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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Aspect Anatomy
aspect authentication //this is the
aspect before call (public void Transfer
(..)) // this is a pointcut // this is
the advice int tries 0 string
userPassword Password.Get ( tries ) while
(tries lt 3 userPassword ! thisUser.password (
) ) // allow 3 tries to get the password
right tries tries 1 userPassword
Password.Get ( tries ) if (userPassword
! thisUser.password ( )) then //if password
wrong, assume user has forgotten to
logout System.Logout (thisUser.uid) //
authentication
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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Aspect Terminology
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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Aspect Weaving

• Aspect weavers process source code and weave the
  aspects into the program at the specified
  pointcuts.

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Aspect Weaving
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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Evolution of Systems Development Methods
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Agenda

• Introduction
• Problem Statement
• Aspect Solution
• Aspect Anatomy
• Aspect Terminology
• Aspect Weaving
• Evolution of Systems Development Methods
• Aspect Oriented Software Development

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Aspect Oriented Software Development

• A holistic approach to developing software
  systems with aspects.
• Better modularity for functional requirements,
  nonfunctional requirements, platform specifics,
  and so on and keeping them separate from each
  other.
• AOSD is not just AOP. It encompasses a whole
  range of techniques to help you achieve better
  modularity.
• object orientation
• component-based development
• design patterns
• object-oriented frameworks such as J2EE and .NET,
  and more

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Aspect Oriented Software Development
... Requirements Engineering
... Architecture
... Design
Aspect-oriented...
... Programming
... Verification techniques
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QA
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• Mostafa Elbarbary
• 012-428-6547
• Mostafa.elbarbary_at_its.ws

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Thank You