Spring Framework

1
Spring Framework

• Kansas City Java Users 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 POJOs
• 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
• 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.

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 ApplicationDependency Injection (DI)
Example
9
Example ApplicationAOP 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 aspects 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 ExampleDI 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