AOP-IOC made by Vi Quoc Hanh and Vu Cong Thanh in SC Team

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Copyright 2011 eXo Platform

IoC & AOPIoC & AOP

Vu Cong ThanhVi Quoc Hanh

Social team

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AgendaAgenda

IoC - Introduction IoC – Definition & Benefits IoC – Concepts IoC – Design your own IoC. Demo AOP - Introduction AOP - Definition & Benefits AOP - Concepts AOP - How it works? Demo

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Inversion Of Control Inversion Of Control (IoC)(IoC)



IoC – Introduction - “Dependencies”



IoC – Introduction – Dependency Problems

»Code is tightly coupled

»Difficult to isolate when testing

»Difficult to maintain.



IoC – Introduction - WITHOUT IoC

»Construction by Hand.

»Factory Pattern.



IoC – Definition & Benefits

»Hollywood principle “Don't call us, we'll call you.”

»Creating, Assembling and Wiring the dependencies into Object graph.

»Type of Dependency Injector:

– Constructor

– Setter

– Method

– Field(Guice)



IoC – Definition & Benefits

»Pros:

– Loosely Coupled

– Increases Tesability

– Separates component clearly.

– Allows for use of Inversion of Control Container.

»Cons:

– Increases code complexity

– Difficult to understand at First

– Complicate Debugging at First

– Complicates following Code Flow.



IoC – Concepts – Time launcher

»Constructed and prepared before it can be used.

– In the init lifecycle stage of a web application.

– On startup of a desktop program



IoC – Concepts– Time launcher

»Constructed and prepared before it can be used.

– On demand, every time it is needed

– Lazily, when it is first needed



IoC – Concepts – Metadata Configuration

»XML configuration file.

»Annotations(@Injector, @Singleton, …)

»Invoking into a programmatic API.



IoC – Concepts - Scope

Fixed duration of time or method calls in which an object exist. General-purpose scopes: Singleton and No-scope.

»Web Application:

– Request, Session and Conversation scope

– Transaction scope



IoC - Concepts - Benefit of Scope

»Lets injector manage the latent state of your objects

»Ensures that your services get new instances of dependencies as needed

»Implicitly separates state by context.



Design your own IoC

Source Code:

Guice: google-guice.googlecode.com/svn/trunk/

Vbox: https://github.com/thanhvc/etk-vbox



Design your own IoC – Injector Diagram



Design your own IoC – Context Diagram



Design your own IoC – State Diagram

StartConstructing Finish

States: Constructing, Start and Finishhttp://www.slideshare.net/Thuy_Dang/regular-expression-made-by-to-minh-hoang-portal-team



Design your own IoC – State Diagram(Cont)

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DEMODEMO

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Aspect Oriented Aspect Oriented Programming (AOP)Programming (AOP)



AgendaAgenda

What is IOC? IOC – Time of Injector IOC – Pros & Cons IOC - Scope Demo AOP - Introduction AOP - Definition & Benefits AOP - Concepts AOP - How it works? Demo



INTRODUCTION - OOP

»A set of objects that interact with each other



INTRODUCTION - AOP

»View the system as a set of concerns



INTRODUCTION – CONCERNS

»A particular role, concept or area of interest



INTRODUCTION - CROSSCUTTING



INTRODUCTION - CROSSCUTTING CONCERNS

»System level requirements that crosscut many core module level requirements



INTRODUCTION – CROSSCUTTING CONCERNS PROBLEMS

»Code tangling, Code scattering, Less code reuse, More difficult evolution...

»Face problem in design when requirements growth



AOP - DEFINITION

»Lets you implement individual concerns in a loosely coupled way and combine these implementations to form the final system.

»Complements object oriented programming.

» Is not about “patching” pieces of code. About performing an action systematically upon recognition of a behavior in the code. behavior in the code.



AOP - BENEFITS

»Modularized implementation of crosscutting concerns behavior in the code.

»Easier-to-evolve systems - extensibility behavior in the code.



AOP - BENEFITS

»Late binding of design decision behavior in the code.

»More code reuse



AOP - CONCEPTS

» Aspect: The merger of advice and pointcuts. All information about where, when and what job is to be done.

» Advice: The job of an aspect. Defines what and when of an aspect.

» Pointcut: Pointcuts help narrow down the joinpoints advised by an aspect. Define the where of an aspect.

» Jointpoint: A point in the execution of an application where an aspect can be

plugged in. All the opportunities for advice to be applied. behavior in the code.



AOP - CONCEPTS

» Target: Object being advised.

» Proxy: The object created after applying advice to the target object.

» Weaving: Process of applying aspects to a target object to created a new proxied object code.



AOP – HOW IT WORKS

» Decorator Pattern

» Proxy Pattern Control access to an object

Allows for object level access control by acting as a pass through entity or a placeholder object. co

d

.



AOP – HOW IT WORKS



AOP – BEHIND THE SCENCES

Aspect

Object_BObject_A

advice

Object Oriented Flow

Aspect Oriented Flow

pointcut = method_B

Target Object = Object_B

Wea

ving

jointpoint = method invocation

Object Oriented Flow



AOP – ENGINES & FRAMEWORKS

» JDK

» CGLIB really create new class through bytecode manipulation code.

» ASPECTJ

» JBOSS AOP

» SPRING FRAMEWORK c

…........ode.

Engines

Frameworks (Java)



AOP vs OOP - CONCLUSION

Object Oriented Aspect Oriented

Class – code unit that encapsulates methods and attributes.

Aspect – code unit that encapsulates pointcuts, advice, and attributes.

Method signatures – define the entry points for the execution of method bodies.

Pointcut – define the set of entry points (triggers) in which advice is executed.

Method bodies – implementations of the primary concerns.

Advice – implementations of the cross cutting concerns.

Compiler – converts source code into object code.

Weaver – instruments code (source or object) with advice.

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DEMODEMO

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Thank you!

AOP-IOC made by Vi Quoc Hanh and Vu Cong Thanh in SC Team

Technology

Transcript of AOP-IOC made by Vi Quoc Hanh and Vu Cong Thanh in SC Team