1. Kansas City Java User’s Group Jason W. Bedell July 12, 2006
Spring Framework
Kansas City Java User’s Group
Jason W. Bedell
July 12, 2006

2. Overview J2EE Alternative
Inversion of Control (IoC) vs. Dependency Injection (DI)
Aspect Oriented Programming (AOP)
Spring Modules
Example Application
Dependency Injection Example
AOP Example
Real-World Application – DI & AOP

3. J2EE Alternative Heavyweight complexity
An easier way to connect disparate components
Enterprise Services using POJO’s
Other players: PicoContainer, HiveMind, Avalon

4. IoC and Dependency Injection
IoC an earlier, more general term
Think “plug-ins”
Behavior is configured instead of programmed.
Dependency Injection is a pattern to achieve IoC
Alternative patterns: Service Locator

5. Aspect Oriented Programming
“AOP enables modularization of crosscutting concerns”
AOP Terms:
Aspects
Joinpoints
Advice
Cutpoints
Introductions
Targets
Proxy
Weaving
Alternative AOP Containers: AspectJ, JBoss

6. AOP Terms Aspects: Joinpoints Advice Cutpoints Introductions Targets
The modularized logic that is being applied throughout an application.
Examples: Logging, Security, Transaction Management, etc.
Joinpoints
An execution point where an aspect can be applied.
Examples: a method being called, a method returning, an exception being thrown, a field being modified, etc.
Advice
The actual implementation of an aspect.
Cutpoints
The joinpoints where advice should be applied.
Introductions
A method or attribute that you introduce to an existing class
Targets
A class that is being advised
Example: Course Service, Student Service, etc.
Proxy
The object created after applying advice to a target object.
Weaving
The process of applying aspects to target objects to create a new, proxied object.
Weaving can occur at compile time, classload time, runtime.

7. Spring Modules The core container Application context module
AOP Module
JDBC abstraction and DAO module
O/R mapping integration module (supports Hibernate, JDO, Oracle TopLink, Apache OJB, and iBATIS)
Web module
MVC framework

8. Example Application Dependency Injection (DI) Example

9. Example Application AOP Example
Determine what Joinpoint to use as our Cutpoint
Implement the Aspect in the form of Advise
Define a Spring Advisor
Spring Advisor: the combination of advice that defines the aspect’s behavior and a pointcut defining where the aspect should be executed.
Spring allows you to define your own advisor or use a predefined, packaged advisor
Define your bean proxy
Inject your Advisor into the Proxy as an Interceptor

10. Real World Example DI & AOP
Application Tier
SpringMVC Framework
Tiles, JSTL
Service Tier
Service POJO Targets
Persistence Tier
DAO POJO Targets
Hibernate Framework
Security Aspect
Acegi Framework Advisor
Transaction Support Aspect
Spring Transaction Management Advisor