A project created to learn basic components of Spring MVC (a popular Java web framework).

The project explores the out of box Spring boot solutions with almost no configuration such as
1. Embedded Tomcat server
2. Embedded/In-memory H2 database
3. Thymeleaf Templating Engine (for mapping static content with dynamic data from model)
4. Maven as a build automation tool

With respect to Spring, a POJO is a Bean with state and behaviour. Unlike EJB's which only holds state, getters and setters for that state.

It is used to transfer the state across the application.

Normal control: Programmer has to take control of object creation, managing application dependencies.

Inversion of control: In this principle, control of object creation, managing application dependencies is moved from developer writing application to the framework itself. Hence, developing application becomes easy.

DI is one of the forms of IOC. It is a technique using which object contruction and usages is separated.
Dependency/Service - A object of a class on which some other class depends
Client - It depends on the service
Injector - Creates the service and inject into the client This way client does not have to worry about creating the object. It just have to use it. Abstraction!

Benefits:

• Depeloper does not have to manage the object creation
• Testing becomes easy using mock object.
• Code becomes more readable.

Note: IOC and DI are similar except that IOC is general concept whereas DI is concrete design pattern.

An interface between database layer and Java layer. It provides ready to use access control mechanisms for data.

A Java class representation of Database table or document.