bcd session 01

8/10/2019 BCD Session 01

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Slide 1 of 24Ver. 1.0

Business Component Development Using EJB Technologies

In this session, you will learn to:

Identify characteristics of Enterprise Java Beans technology,

for EJB 3.0 specification

Identify the use of annotations

Define the Java Platform, Enterprise Edition (Java EE)Examine the Java EE application architecture

Examine the EJB application creation process

Compare the Java EE application development with traditional

enterprise application development

Objectives


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EJB 3.0 Specification

Enterprise JavaBeans (EJB) is defined as a server-side

component framework that builds enterprise-class

distributed component applications in Java.

You can create scalable, reliable, transactional, secure, and

multi-user distributed applications by using EJB.EJB is designed to support application portability and

reusability across any vendors enterprise middleware

services.

The new EJB3.0 API offers ample of simplification over the

previous version EJB API.


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Prior to EJB 3.0

The following list briefly describes some of the general EJB

2.x implementation artifact:

Enterprise bean class

EJB object

Remote interfaceLocal interface

Home interface

Deployment descriptor

Vendor-specific files

The Ejb-jar file


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EJB 3.0 Enterprise Bean

EJB 3.0 beans are the Plain Old Java Object (POJO) styled

beans as opposed to pre-EJB 3.0 enterprise beans that

used to constitute multiple Java classes and interface per

EJB component.

EJB 3.0 bean has all its code contained in a single Javaclass.

EJB 3.0 enterprise bean provides a single business

interface for both local and remote clients.

EJB 3.0 bean provides a bean class that provides definitions

of only the business interface.EJB 3.0 bean does not have a home interface.

A message-driven bean, in EJB 3.0, doesnt need a

business interface.


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EJB 3.0 Enterprise Bean (Contd.)

The bean provider is not required, in EJB 3.0, to implement

the component interface regardless of whether it is needed

or not.

The bean class does not have to implement the component

interfaces, javax.ejb.SessionBean for a session bean orjavax.ejb.MessageDrivenBean for a message-driven bean.


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Annotations

The use of annotation is one of the most important features

of EJB 3.0 specification.

They have been added to the java language in Java Service

Request 175 (JSR) and made available since the release of

Java 5 platform.Annotation is defined as the metadata that consists of the

additional definition that can be attached inside your source

file.

They can be used as an alternative to the standard XML

deployment descriptor files.Java annotations provide information about the code in the

code itself. They are complied and type-checked. They can

be accessed at the runtime by using Java reflection, but

cannot perform computation.


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Annotations (Contd.)

Annotations can be applied to various elements of the Java

code such as methods, variables, constructors, package

declarations, and so on.

Annotations begin with an @ sign followed by the

annotation name which in turn is followed by annotationdata.

You can use annotations if:

The metadata you are applying changes the design of the

class.

The metadata changes the design of code interacting with theclass.




Annotations (Contd.)

Benefits of using annotations in Java:

Annotations are compiled by Java language compiler,

therefore no external tools are required.

Annotations are potable, because the metadata is

standardized.

Annotations on a class can be kept in a class file and retained

for accessing at the runtime.

Drawbacks of annotations:

Annotation cannot form an inheritance hierarchy like interfaces

and classes.

Annotation data member types are restricted to primitive types,

String, Class, enum, annotation types, and arrays of the

preceding types.

You must access permission on the code, to annotate it.




Java EE is the standard for developing portable, robust,

scalable, and secure server-side Java applications.

The Java EE platform consists:

A set of specifications.

Java EE 5 Software Development Kit (Java EE 5 SDK).Commercial and open source Java EE application servers and

tools.

Java EE components and applications.

Introducing the Java Platform Enterprise Edition (Java EE)


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Examining the Java EE Application Architecture

The key features of the component-container architecture

are:

Separation of application specific functionality and application

generic functionality.

Components consist of application specific functionality.

Containers consist of the generic functionality common to all

enterprise applications.

Containers provide an execution environment for components.

Containers provide services for components.


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Examining the Java EE Application Architecture (Contd.)

The following figure shows the component-container

architecture.


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The following figure shows the Java EE containers

associated with the Java EE platform.


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The following table lists the containers, components and the

machines that host the containers.

Container Compo nent Type Container Host

EJB container EJBs EJB container is part of the Java EE

application server.Web container Servlets and

JavaServer

Pages (JSP)

EJB container is part of the Java EE

application server.

Applet

container

Applets Applet container can be a web browser or

other application that supports the applet

programming model. The applet container is

hosted on a client machine.

Application

client

container

Application client

component

Application client container is hosted by the

client machine.

Web browser Web pages Web browser is hosted by the client

machine.


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The following figure shows the Java EE application

architecture with the inclusion of the application

function-specific components.


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Examining Java EE Container Services (Contd.)

Vendor-specific functionality- Vendor-specific functionality can

include clustering, which addresses:

Scalability.

Failover.

Load balancing.

API-based services- The supporting services and APIs that areincluded in the Java EE platform are:

Java DataBase Connectivity (JDBC) API for database

connectivity

JNDI API

RMI over Internet Inter-Object Request Broker (ORB) Protocol

(IIOP) and the interface definition language (IDL) for the Java

application

JavaMail API and JavaBeans Activation Framework (JAF) API

Java EE Connector Architecture

JMS API


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JMS API

JTA

Java Authentication and Authorization Service (JAAS)

Java API for XML Processing (JAXP)

Web services integration features

JMXTimer services


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The following figure shows the accessibility of important

API-based services with Java EE containers.


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Examine the EJB Application Creation Process

Adhere to the following steps to create an EJB application:

1. Use your preferred object oriented methodology to analyze the

business problem.

2. Analyze the inter-tier communications requirements.

3. Use entity classes to model the persistence data.

4. Use session beans and synchronous service faade.

5. Use the JMS API and message-driven beans.

6. Create the client.

7. Assemble and package the application.

8. Deploy the server-side components.9. Package and distribute the client.


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Examine the EJB Application Creation Process (Contd.)

The following figure shows the creation of Java EE

components and their assembly into Java EE modules.


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Comparing Java EE Application Development With Traditional Enterprise Application Development

Java EE platform:

Provides strict separation of the application components from

the general services and infrastructure.

Helps the developers to focus on the application business

logic.


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Comparing Java EE Application Development With Traditional Enterprise Application Development (Contd.)

The following figure shows the advantages of using

server-provided services.


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In this session, you learned that:

Enterprise JavaBeans (EJB) is defined as a server-side

component framework that builds enterprise-class distributed

component applications in Java.

EJB 3.0 beans are the POJO styled beans as opposed to

pre-EJB 3.0 enterprise beans that used to constitute multipleJava classes per EJB.

The home interface and the component interface are

eliminated from EJB 3.0 enterprise bean.

Annotation, defined as the metadata, consists of the additional

definition that can be attached to an element within the code tohelp further explain.

Summary


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Annotations can be applied to various elements of the Java

code such as:

Methods

Variables

Constructors

Package declarationsJava EE is the industry standard for developing portable,

robust, scalable, and secure server-side Java applications.

The Java EE component model relies on both container-based

and platform services.

Java EE services can be grouped into the following categories:Deployment-based

Inherent services

Vendor-specific functionality

API-based services

Summary (Contd.)

bcd session 01

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