Spring

A framework for building Java applications, provides:

• IOC container
• Dependency Injection
• Aspect-Oriented Programming (AOP)
• Abstractions for web, data, security, messaging, etc.

Spring itself is modular, not a full product. (like a toolbox)

Issue:

• Manually configure:
  • DataSource
  • TransactionManager
  • EntityManagerFactory
  • DispatcherServlet
• Write lots of XML / Java config
• Manage server: Tomcat / Jetty separately
• Handle dependency version conflicts manually

Flow

Application Start
 ↓
Create ApplicationContext (create IOC container)
 ↓
Scan Classpath
 ↓
Read Bean Definitions
 ↓ 
Build Dependency Graph (Analyze and build)
 ↓
Instantiate Beans
 ↓
Inject Dependencies (DI)
 ↓
Lifecycle Callbacks
 ↓
Application Ready