What is an Application Server ?

What is an Application Server ?

Ø Application server is a Server Software comprises of web container,EJB Container and other enterprise services. Via.JNDI naming Services JMS,JTS etc.,

Example of some of Application Servers :

·         Weblogic8.1 / weblogic 10

·         JBoss

·         Sun Server

·         WebSphere(WAS from IBM)

·         GlassFish

What is J2EE

What is J2EE ?

Ø J2EE(java 2 Enterprise Edition) is one of the three Java platform from sun micro system.

            Other two’s are :   (1) J2SE(Java 2 Standard Edition)

                                                 (2) J2ME(Java 2 Mobile Edition)

Ø J2EE is a collection of so many Java based technologies.

Ø J2EE technologies broadly divided into 2 catagories

o   Component technologies

o   Service technologies

Component technologies are :

o   Servlets

o   Jsp

o   EJB(enterprise java beans)

·        Servlets and jsp are know as web technologies

·        EJB is known as distributed technologies

·        A servlet and jsp are web components developed by web component developers

·        EJB’s are develooped by business component developers .EJB’s are knows as business components.

Service technologies are :

o   JMS (Java Messaging Service)

o   JTS (Java Transaction Service)

o   JAAS (Java Authentication and autherisation Service)

o   JNDI (Java Naming and directory Interface)

o   Java Mail

Distributed Architecture

Ø If business objects of a service layer are geographycally dispresed in the network and still communicating with one another such enterprise application is said to be distributed appliaction and is said to have distributed tier architecture

N-tier Architecture

Ø An extension of 3-tier architecture is nothing but n-tier architecture

Ø Service layer is one machine ;data layer in one machine; presentation layer is in morethan one machine.i.e. windows based enterprise application can be 3-tier architecture cannot be ‘n’ tier as presentation layer runs in only one machine as one process.

Ø Web-enabling a 3-tier architectural enterprise application is nothing but making it n-tiered.

3-tier architecture

Ø Physical seperation of service layer(data access layer as well) from the presentation layer is nothing but 3-tier architecturre.

Ø One machine for one machine for service layer( and DAL also) and another machine for presentation layer is the actual physical seperation in this architecture.

Ø 3-tier architecture eliminates client side maintainance.it also makes the clients thin

Ø 3 tier architecture does not make the client 100% thin.

2-tier (Client-server)architecute

     Ø 2-tier architecture is also known as client-server architecture.

Ø In two tier architecture always server is the database server(data layer).

Ø In such physical and data access layer run in one machine which is nothing but client machine.