Introduction to Spring Framework

Introduction: 

Spring is an open source framework created to address the complexity of enterprise application development. Enterprise applications has a tremendous need of wiring objects or implementing different behavior of object at runtime that too without imposing much load on application. One of the main advantages of the Spring framework is its layered architecture design, which allows us to wire the objects as and when necessary with reduced maintenance efforts.

Core Features of Spring

• Lightweight:

1.      Spring provides you different modules and allows you to use any one based to your requirement.  Ideally the spring jar is just 2-3 MB. 

2.      If you compare Spring with EJB, then you have to write very less code and configurations too. The beauty of Spring is that you can actually focus on business logic whereas in EJB you have to write lot of code along with business logic which makes the code bulky and tightly coupled.

3.      Through Spring you are playing with POJO which do not depends on Framework and it improves the testability of your code. 

4.      And, Spring provides seamless integration with frameworks, third party libraries etc.

• Inversion of control (IOC):

The Inversion of Control (IoC) and Dependency Injection (DI) patterns are all about removing dependencies from your code.. No need to directly connect your components and services together in program, instead just describe which services are needed by which components in a configuration file/xml file. The Spring IOC container is then responsible for binding it all up.

• Aspect oriented (AOP): 

Aspect oriented programming refers to the programming paradigm which isolates secondary or supporting functions from the main program's business logic. AOP is a promising technology for separating crosscutting concerns, something usually hard to do in object-oriented programming. The application's modularity is increased in that way and its maintenance becomes significantly easier.

• Container:

Spring contains and manages the life cycle and configuration of application objects.

• MVC Framework:

Spring comes with MVC web application framework, built on core Spring functionality. This framework is highly configurable via strategy interfaces, and accommodates multiple view technologies like JSP, Velocity, Tiles, iText, and POI. But other frameworks can be easily used instead of Spring MVC Framework.

• Transaction Management:

Spring framework provides a generic abstraction layer for transaction management. This allowing the developer to add the pluggable transaction managers, and making it easy to demarcate transactions without dealing with low-level issues. Spring's transaction support is not tied to J2EE environments and it can be also used in container less environments.

• JDBC Exception Handling:

The JDBC abstraction layer of the Spring offers a meaningful exception hierarchy, which simplifies the error handling strategy. Integration with Hibernate, JDO, and iBATIS: Spring provides best Integration services with Hibernate, JDO and iBATIS

Architecture:

Spring is well-organized architecture consisting  of seven modules. Modules in the Spring framework are:

1. Spring AOP:

One of the key components of Spring is the AOP framework. AOP is used in Spring:

• To provide declarative enterprise services, especially as a replacement for EJB declarative services. The most important such service is declarative transaction management, which builds on Spring's transaction abstraction.
• To allow users to implement custom aspects, complementing their use of OOP with AOP
1. Spring ORM:

The ORM package is related to the database access. It provides integration layers for popular object-relational mapping APIs, including JDO, Hibernate and iBatis.
  

3. Spring Web:

The Spring Web module is part of Spring?s web application development stack, which includes Spring MVC.

·  Spring DAO:

The DAO (Data Access Object) support in Spring is primarily for standardizing the data access work using the technologies like JDBC, Hibernate or JDO.
 

·  Spring Context:

This package builds on the beans package to add support for message sources and for the Observer design pattern, and the ability for application objects to obtain resources using a consistent API.
  

·  Spring Web MVC:

This is the Module which provides the MVC implementations for the web applications.
  

·  Spring Core:

The Core package is the most import component of the Spring Framework. 
This component provides the Dependency Injection features. The BeanFactory  provides a factory pattern which separates the dependencies like initialization, creation and access of the objects from your actual program logic.

In my next blog post I will let you dive in Dependency injection(ioc) in spring

Keep posting your queries if any