Simplistic view of Spring

What is Spring?

TO bare minimum Spring is
Lightweight - Non-intrusive to your applications
Dependency Injection
Aspect-Oriented
Container - configuration and Management of lifecycle of Application objects
Framework - compose complex applications from simple components

What are spring modules? and why its there?

On top of these 6features, spring provides ready made modules to easy development. Otherwise if this is not something you are after you can plug-in/configure your own modules. Also Spring provides integration points to plugin other modules e.g. Hibernate

 Spring framework is made up of six modules

1. Core Spring cotainer
2. DataAccess & integration
3. AOP
4. Testing
5. Web and Remoting
6. Instrumentation

(Image take from Spring in Action Ed 3MEAP, first chapter available on Manning website)

What is Spring Core?

- Spring Core is made up of BeanFactory and ApplicationContext

- BeanFactory provides configures and manages bean instances using DI

- Application Context provides a way to configure Spring.

- Spring supports several implementations,

What is Data Access and Integration?

Spring doesnt have any ORM on its own, it just has Spring JDBC (core class JDBCTemplate)
It provides integration points with tools like Hibernate

What is web and remoting module?

Spring provides Spring MVC and Spring Portlet for web

Also supports Struts like frameworks...

Remoting has support for RMI and JAX-WS (contract first approach)