Martin: Created page with "Refernces: * http://java.sun.com/javaee/5/docs/tutorial/doc/ * http://java.sun.com/javaee/technologies/ == Web Component == * JSP - Script * Servlets - Class files (compiled..."

2021-09-14T21:18:10Z

Created page with "Refernces: * http://java.sun.com/javaee/5/docs/tutorial/doc/ * http://java.sun.com/javaee/technologies/ == Web Component == * JSP - Script * Servlets - Class files (compiled..."

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Refernces:
* http://java.sun.com/javaee/5/docs/tutorial/doc/
* http://java.sun.com/javaee/technologies/

== Web Component ==
* JSP - Script
* Servlets - Class files (compiled)
* JSF - Framework based on JSP + Servlets

* Html + Server utility classes
** these are not considered web components but can be bundled with the web components

- May include java beans that talk to the business tier

=== Web Service support ===

* web based application - open XML standards + transports
* JEE provides XML API and tools

Web services - method + parameters

Document oriented - document containing service data

XML - cross platform, extensible, text based

=== SOAP - Simple Object Access Protocol ===

*Envelope* describes message and how to process

*Body* Encoding rules to express app, defined data types, convention used to represent request and response

==== WSDL - Web Service Definition Language ====
XML format for describing network services
* description, name, location, communication mechanism (transport)
* can be stored in UDDI or published - web

UDDI + ebXML - allows publishing of services

== Business Component ==
* EJB Enterprise beans that solve business needs
** Stores and retrieves information from the EIS (Enterprise Information System)

== Enterprise Information System ==
may contain:
* ERP - Enterprise resource planning
* Mainframe transaction processing
* Database
* Other legacy

== Java EE Containers ==
* component based - organises business logic into components
* provides underlying services
* requires assembly into a module and deployment
** specifying component settings for each component e.g. transaction management, JNDI, remote connectivity
* Transaction model allows relationships of methods to be defined
* JNDI - unified naming and lookup mechanism across directory services
* Remote connectivity - manages low level connectivity clients -> EJB

Security can be configured differently in different environments

Container manages non configurable items
* EJB + servlet live cycle
* DB pooling
* Persistence
* Access to JEE API

JEE Server = EJB container + Web Container

=== Deployment ===
* Functional components + optional deployment descriptors
* via platform specific tools - specifying user access + DB access

=== Packaging ===
* JEE app = EAR file (Enterprise Archive - standard jar format)

/Web module (.war)
/Application client module (.jar)
/Resource Adaptor (.rar)
/EJB module (.jar)
/META-INF/application.xml - JEE deployment configuration - root of web app, protable naming mappings
/META-INF/sun-application.xml - runtime - app specific runtime e.g. caching options

Deployment configuration can be changed without need to modify code and rebuild

== Deployment roles ==
* Tool provider - provider of development, packaging tools
* Application component provider - develops beans/applets/clients etc
** Enterprise Bean developer
** Web component developer
** Application client developer - client jar file
* Application assembler - assembles war,jar files into ear + writes deployment descriptors
* Application deployer + administrator - configures deploys application, administers servers, JEE, network etc.

== Simplifies System integration ==
* platform independent system integration solution
* unified application model across tiers with EJB
* simplified request/response - Servlets/JSP
* reliable security model - JAAS
* XML data interchange - JAXP, SAAJ, JAX-WS
* interoperability - JCA
* easy DB connectivity - JDBC
* enterprise application integration with JMS, JTA, JNDI

== Protocols ==
Standard web based protocols:
* TCP
* HTTP 1.0
* SSL 3.0
* RMI (Remote Method Invocation) Serialisation + JRMP (Java Remote Messaging Protocol)
** OMG protocols (Object Management Group)
** CORBA (Common Object request Broker Architecture)
*** Defines interface in IDL (Interface Definition Language)
*** IDL compiled into client and server stubs
** ORB (Object Request Broker)
*** Communicates using IIOP (Internet Inter Orb Protocol)
Requires:
* Java IDL - idlj - hava compiler - generates java stubs from IDL
* RMI-IIOP - RMI implementation over IIOP

From [URL="http://en.wikipedia.org/wiki/RMI-IIOP"]wikipedia [/URL]

Both CORBA and RMI-IIOP use the same GIOP communication standard. If required, it is possible to generate the IDL definitions for the involved RMI-IIOP data structures and use these definitions to arrange the interoperability between the RMI-IIOP and plain CORBA applications.

There is a program that will generate the idl:
http://java.sun.com/j2se/1.4.2/docs/guide/rmi-iiop/rmi_iiop_pg.html

So though RMI-IIOP is CORBA compiant it needs work for corba clients to integrate.

java IDL is the typical way to integrate with an existing CORBA application.

java EJB is RMI-IIOP and CORBA can integrate but needs IDL to be generated (with the help of rmic)

http://java.sun.com/javase/6/docs/technotes/guides/idl/jidlFAQ.html

* Java IDL - existing CORBA application - mainly CORBA/C++ based.
* RMI-JRMP - (Application Servers see below). Designed for java.
* RMI-IIOP - Used by Application Servers - part of spec. Mostly java based but want to maintain legacy applications.

== Data formats ==
* HTML
* Image files: gif + jpeg
* JAR
* Class
* XML

J2EE Basics - Revision history

Martin: Created page with "Refernces: * http://java.sun.com/javaee/5/docs/tutorial/doc/ * http://java.sun.com/javaee/technologies/ == Web Component == * JSP - Script * Servlets - Class files (compiled..."