pect Oriented Programming

1
pect Oriented Programming
AOP
S
A

• hinking on the level of Concerns

T
2
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

3
volution of software programming methodology
E
AOP

• Direct machine-level coding
• Structured programming
• Object Oriented Programming
• Aspect Oriented Programming

4
volution of software programming methodology
E
AOP

• Direct machine-level coding

00110101011001100110011011100010110010011001101110
0000
Thinking about the machines instruction set more
than the problem it self
5
volution of software programming methodology
E
AOP

• Structured programming

Algorithm A
Algorithm B
DS B
Input
Design the Algorithm then Design the Data
DS C
Algorithm D
Algorithm C
DS D
Output
6
volution of software programming methodology
E
AOP

• Object Oriented Programming

Object A
Object C
Object B
A set of objects that interact with each other
Object F
Object E
Object G
Object D
7
volution of software programming methodology
E
AOP

• Aspect Oriented Programming

Crosscutting Concern A
Crosscutting Concern B
Crosscutting Concern C
Crosscutting Concern D
View the system as a set of concerns
Weaver
End System
8
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

9
ystem Crosscutting concerns
S
AOP

• Concern

A particular goal, concept, or area of interest
10
ystem Crosscutting concerns
S
AOP

• Crosscutting Concerns

Crosscutting concerns
System Level Requirements
System level requirements that crosscut many core
module level requirements
Logging
Security
Authen.
Analyze
Module A
Module B
Module C
Requirements
Core Module Level Requirements
11
ystem Crosscutting concerns
S
AOP

• Crosscutting Concerns Problems

Poor traceability Lower productivity Less code
reuse Poor code quality More difficult
evolution
12
ystem Crosscutting concerns
S
AOP

• Crosscutting Concerns Problems

Current Responses
13
ystem Crosscutting concerns
S
AOP

• Crosscutting Concerns Problems

The architect's dilemma
14
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

15
undamentals of AOP
F
AOP

• Aspect Oriented Programming

Orthogonal Concerns
lets you implement individual concerns in a
loosely coupled fashion, and combine these
implementations to form the final system.
16
undamentals of AOP
F
AOP

• AOP Development Steps

Final System
Aspectual Recomposition
Aspectual Decomposition
Aspects
Concerns Implementation
1
2
3
17
undamentals of AOP
F
AOP

• AOP Development Steps

Example
CreditCardProcessor
System Concerns
Logging
1 - Aspectual Decomposition
18
undamentals of AOP
F
AOP

• AOP Development Steps

Example
public class CreditCardProcessor      public
void credit(CreditCard card,Currency amount)
        throws InvalidCardException // logic

public interface Logger     public void
log(String message)
2 - Concerns Implementation
19
undamentals of AOP
F
AOP

• AOP Development Steps

Example
CreditCardProcessor

• Log each public operation's beginning
• Log each public operation's completion

weaving rules
Logging
Final System
3 - Aspectual Recomposition
20
undamentals of AOP
F
AOP

• AOP Development Steps

Example
public class CreditCardProcessor   Logger
logger public void credit(CreditCard
card,Currency amount) throws InvalidCardExceptio
n logger.log("Starting CreditCardProcessor.
credit(CreditCard,Money) "
"Card " card " Amount " amount) //
Crediting logic logger.log("Completing
CreditCardProcessor.credit(CreditCard,Money) "
"Card " card "
Amount " amount)
Final System
21
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

22
natomy of AOP languages
A
AOP

• The AOP language specification
• AOP language implementation

23
natomy of AOP languages
A
AOP

• The AOP language specification

Describes language constructs and syntax
Implementation of concerns
Weaving rules specification
public class CreditCardProcessor      public
void credit(

• Log each public operation's beginning
• Log each public

24
natomy of AOP languages
A
AOP

• AOP language implementation

• Combine the individual concerns
• Convert the resulting information into executable
  code

Source-to-Source Translation
VM Implementation
25
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

26
OP benefits
A
AOP

• Modularized implementation of crosscutting
  concerns
• Easier-to-evolve systems
• Late binding of design decisions
• More code reuse

27
OP benefits
A
AOP

• Modularized implementation of crosscutting
  concerns

Logging
Auth.
Module A
Security
Security
Logging
Auth.
Assembling Rules
System Modules
With AOP
Without AOP
28
OP benefits
A
AOP

• Easier-to-evolve systems

To Add New Feature
New Feature
Logging
Auth.
Module A
Security
Security
Logging
Auth.
New Feat.
Assembling Rules
System Modules
Without AOP
With AOP
29
OP benefits
A
AOP

• Late binding of design decisions

Module E
Module A
Module B
Module F
Module A
Module B
Expected Module
Expected Module
Expected Module
With AOP
Without AOP
30
OP benefits
A
AOP

• More code reuse

Pure Module Logic
Security
Module Logic
Module Logic
Auth.
Logging
With AOP
Without AOP
31
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

32
spectJ overview
A
AOP
AspectJ is a language specification as well as an
AOP language implementation.
AspectJ's language constructs extend the Java
programming language
provides an aspect weaver in the form of a
compiler
33
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

34
spectJ Language Overview
A
AOP

• Joinpoints

int x getXValue() if(x gt 10) print(X gt
10) else print(X lt 10)
Points in a program's execution
35
spectJ Language Overview
A
AOP

• Pointcuts

At if(x gt 10) collect x
Program constructs to designate joinpoints and
collect specific context at those points
int x getXValue() if(x gt 10) print(X gt
10) else print(X lt 10)
36
spectJ Language Overview
A
AOP

• Advice

Code that runs upon meeting certain conditions
At if(x gt 10) collect x
int x getXValue() if(x gt 10) print(X gt
10) else print(X lt 10)
Print(X x)
Advice
37
spectJ Language Overview
A
AOP

• Aspect

Pointcut
Advice
Weaving Rule

Pointcut Pointcut Pointcut Pointcut ...
Advice Advice Advice Advice ...

ASPECT
38
GENDA
A
AOP

• Evolution of software programming methodology
• System Crosscutting concerns
• Fundamentals of AOP
• Anatomy of AOP languages
• AOP benefits
• AspectJ overview
• AspectJ Language Overview
• AspectJ language concepts and constructs

39
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

AspectJ makes the following pointcuts available

• Method call and execution
• Constructor call and execution
• Read/write access to a field
• Exception handler execution
• Object and class initialization execution

40
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

• Method call and execution

Call(public void MyClass.myMethod(String))
Call(MyClass.new()) Call(MyClass.new()) Call
( MyClass.myMethod())
int x 10 MyClass.myMethod(Hello) if(x lt 10)
41
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

• Constructor call and execution

execution(public void MyClass.myMethod(String)) e
xecution( MyClass.myMethod(..)) execution(publi
c com.mycompany...(..)) execution(MyClass.n
ew(..))
Public void myMethod() ...
42
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

• Read/write access to a field

Public void myMethod() int y
getY() print(y) ...
get(int MyClass.x) set(String MyClass.name)
43
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

• Exception handler execution

Public void myMethod() try // catch()
//
handler(RemoteException) handler(IOException)
handler(CreditCard)
44
spectJ language concepts and constructs
A
AOP

• Joinpoints Pointcuts

• Object and class initialization execution

Class MyClass static //
staticinitialization(MyClass) Staticinitializatio
n(MyClass)
45
spectJ language concepts and constructs
A
AOP

• Advices

AspectJ provides three ways to associate an
advice with a joinpoint
Before
Joinpoint
Around
After
46
spectJ language concepts and constructs
A
AOP

• Advices

Before
before() call(public MyClass.(..))
        System.out.println("Before "
thisJoinPoint " " System.currentTimeMillis(
))
47
spectJ language concepts and constructs
A
AOP

• Advices

After
after() call(public MyClass.(..))
        System.out.println("After "
thisJoinPoint " " System.currentTimeMillis(
))
48
spectJ language concepts and constructs
A
AOP

• Advices

Around
void around(Connection conn) call(Connection.clo
se()) target(conn)     if
(enablePooling)         connectionPool.put(conn)
     else         proceed()    
49
spectJ language concepts and constructs
A
AOP

• Aspects

public abstract aspect AbstractAuthenticationAspec
t     public abstract pointcut
operationsNeeddingAuthentication()    befor
e() operationsNeeddingAuthentication()
        // Perform authentication. If it could
not be // authenticated, let the exception
thrown by         // authenticate
propagate.        Authenticator.authenticate() 
   
50
spectJ language concepts and constructs
A
AOP

• Aspects

public aspect DatabaseAuthenticationAspect
    extends AbstractAuthenticationAspect
    public pointcut operationsNeeddingAuthentic
ation()        call( DatabaseServer.connect())

51
eferences
R
AOP

• I want my AOP! By Ramnivas Laddad
• Introduction to Aspect-Oriented Programming By
  Graham O'Regan

52
uestions
Q
AOP
?