Introduction to Spring

Spring framework is a light-weight container for development of Enterprise applications. Spring is used to configure transaction management, remote accessing using RMI or web services, mailing facilities and persisting data to the database. Spring is a multi-purpose technology, it is used in standard mode to allow, use in parts and leave the other components which is not required by the application.

Features of Spring Framework:

Transaction Management: Spring framework is uses transaction management to handle all transactions. It allow java developer to add the pluggable transaction managers, and building it easy to transactions without considering with low-level issues.
JDBC Exception Handling: The JDBC abstraction layer of the Spring offers a significant exception hierarchy, which alters the error handling strategy.
Integration with Hibernate, JDO, and iBATIS: Spring provides most beneficial Integration services with Hibernate, JDO and iBATIS.
AOP Framework: Spring is most beneficial AOP framework
MVC Framework: Spring goes with MVC web application framework, constructed on core Spring functionality. This framework is extremely configurable via strategy interfaces, and suits multiple view technologies like JSP, Velocity, Tiles, iText, and POI.

Spring Architecture
Spring framework is well-organized architecture  consisting of seven modules. These are:
1. Spring AOP: This is the one of the most  important components of Spring framework. AOP is used in Spring:

    
    To provide 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
    

2. Spring ORM: This ORM package is used to  access the database. It allows for integration layers of popular  object-relational mapping APIs, including JDO, Hibernate and iBatis.
3. Spring Web: The Spring Web module is  part of Spring web application development stack, which includes Spring MVC.
4. Spring DAO: The DAO (Data Access  Object) defend in Spring is primarily for standardizing the data access work  using the technologies like JDBC, Hibernate or JDO.
5. Spring Context: This package constructs  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.
6. Spring Web MVC: This is the Module  which provides the MVC implementations for the web applications.
7. Spring Core: This package is the most  import component of the Spring Framework. It 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.