Table of Contents

• Objective
• What is the spring Framework?
• Why Spring framework came out?
• What is spring architecture?
• Spring Beans
  • What is a bean?
  • What is bean scope?
  • What is bean life-cycle?
• What is dependency injection & inversion of control?
• What is aspect-oriented programming?
• Spring MVC
  • What is Spring MVC?
  • Why to use Spring MVC
  • Structure of spring MVC
• Hibernate
  • What is hibernate?
  • What is an entity life-cycle?
  • What is cascading and their types?
  • Difference between eager and lazy loading
• Resources

Objective

• grasp spring concepts
• learn the theory behind the Spring framework

What is the Spring Framework?

• it's a web framework for building web apps using java
• released in 2004

Why Spring framework came out?

• to solve complex configurations in a java enterprise edition that uses java enterprise beans (EJB)
• also to enhance poor performance
• create loosely coupled software

What is spring architecture?

• spring introduces a layered architecture; each layer contains a set of modules (~20 modules)
• through this layered architecture spring achieved one-stop-shop philosophy
• Modules:
  1. Core: contains dependency injection and inversion of control which uses a factory design pattern
  2. Aspect-oriented programming: to remove cross-cutting concerns
  3. Data access: contains JDBC, ORM
  4. Web: contains servlets, web sockets

Spring beans

What is a bean?

• Simply, a bean is a java object which is created and destroyed through spring IOC and DI

What is bean scope?

• bean scope is responsible for deciding:

  1. How long will the bean live?
  2. How many instances will be created?

  Scope	Description
  Singleton	Default scope, create one instance per Spring container
  Prototype	Create a new instance every time the bean is requested
  Request	Single bean instance per HTTP request
  Session	Single bean instance per HTTP session
  Global-session	Single bean instance per global HTTP session

What is bean life-cycle?

What is Dependency Injection and Inversion of control?

• It's a process of delegating instantiation and assembling objects into:
  1. XML files
  2. XML using annotations
  3. other java code
• and to inject object dependencies you have to use:
  1. Constructor injection
  2. Setter injection

What is aspect-oriented programming?

• it's a programming paradigm that aims to increase modularity by separating cross-cutting concerns
• Steps:
  1. Define point-cut (logger, security) "cross-cutting concern"
  2. Define those points into something called aspect
  3. Define configuration for each aspect (when-where you want to call this aspect)

Spring MVC

What is spring MVC?

• It's a spring framework for building web-apps by applying model-view-controller architectural style

Why to use spring MVC?

• Separation of concerns which make your app able to:
  1. scale easily.
  2. be tested
  3. be developed in a fast and parallel fashion

Structure of spring MVC

Hibernate

What is hibernate?

• It's an object-relational mapping that relies on a layer in between app and database to handle conversion between tables and classes
• Java App ⇒ hibernate ⇒ JDBC ⇒ DB

What is an entity life-cycle?

1. transient (un-tracked)
2. persist (attached to the database so any change that happens will reflect on the database)
3. detached
4. removed

What is cascading and their types?

• Apply the same changes-operations to related entities
• Types:
  1. Save
  2. Delete
  3. Detach
  4. All
  5. Remove
  6. merge

Difference between eager and lazy loading

• Eager: loads all data at once
• Lazy: loads data whenever it's required-requested

Resources

• Coursera
• Udemy
• Youtube: Spring Framework
• Youtube: Spring MVC