J2EE Overview Version 1.0.

Course Objective •The Objective of J2EE course are: – To understand multi-tiered enterprise applications. – To understand J2EE framework for developing enterprise applications. – To understand various components of J2EE like JSP, Servlets, EJB etc. and effectively use them. – To understand Application Server and its configurations. – To learn and deploy web based applications in application server. – To learn supporting technologies like TCS Internal

September 3, 2009

What is WWW •The WWW incorporates all of the Internet services above and much more. •You can retrieve documents, view images, animation, and video, listen to sound files, speak and hear voice, and view programs that run on practically any software in the world, provided your computer has the hardware and software to do these things.

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How does WWW work

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HTTP •HTTP defines the requests that a client can send to a server and responses that the server can send in reply •Each request contains a URL, which is a string that identifies a Web component or a static object such as an HTML page or image file.

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HTTP Communication

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HTTP Commands •GET - retrieves the resource identified by the request URL. •HEAD - returns the headers identified by the request URL. •POST - sends data of unlimited length to the Web server. •PUT - stores a resource under the request URL. •DELETE - removes the resource identified by the request URL. •OPTIONS - returns the HTTP methods the server supports. •TRACE - returns the header fields sent with the TRACE request. TCS Internal

September 3, 2009

HTTP Request •An HTTP request is sent by the browser to server. It will have the command, the requested object, protocol, and any additional attribute passed along with the object. Eg: GET /reports/sales/index.html HTTP/1.0

Component/ Object

Protocol/ Version

Command

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HTTP Response •An HTTP message sent by a server to a client is called an HTTP response. The initial line of an HTTP response is called the status line. •It has three parts, separated by spaces: the HTTP version, a response status code that tells the result of the request, and an English phrase describing the status code. HTTP/1.0 200 OK Date: Tue, 01 Dec 2001 23:59:59 GMT Content-Type: text/html Content-Length: 52

Hello, John!

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Web Application •An obvious but still accurate definition of a web application is that it is an application that is accessible from the web! •Normally, web server serves static content only. •To build a web application, we write small programs on the server. •When the user requests for this script, it is executed on the server and the output (which is a HTML file) is sent to the client.

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September 3, 2009

J2EE •Java 2 Platform, Enterprise Edition (J2EE) defines the standard for developing component-based multi-tier distributed enterprise applications. •A J2EE component is a self-contained functional software unit that is assembled into a J2EE application along with related components. •An enterprise-level platform for developing portable, secure, scalable, distributed, multitier business applications. TCS Internal

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J2EE (contd.) •Application logic is divided into components according to function •The various application components that make up a J2EE application are installed on different machines depending on the tier in the multitiered J2EE environment to which the application component belongs

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J2EE Multi-tier Framework

ANY CLIENT

WEB CLIENT

Client Tier

JSP/Servlet Container

Web Tier

EJB Container

Database/Legacy Systems

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Business Tier EIS Tier

Client Machine

J2EE Server

Database Server / Legacy Server

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J2EE Architecture CLIENTS TIER External Clients from INTERNET (Browsers , WAP etc.) Applets

J2EE WEB APPLICATION SERVER TIER PRESENTATION LOGIC

BACK END TIER

BUSINESS LOGIC (EJB Container )

(Web Components)

SERVLETS

JSP

EJB

EJB

EJB

EJB

Enterprise Information Systems

EJB

EJB

(Databases, ERP, Legacy Systems)

XML Internal Clients from INTRANET (Browsers , Desk top Applications etc.) Applets, Javabeans

ENTERPRISE SERVICES WML JDBC

JNDI

JMS

JTS

HTML RMI - IIOP

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J2EE offerings for Developer Java Authentication & Authorization Service

Enterprise Java Beans

Java Naming & Directory Interface

JAXP – JAXB – JAXR – JAXRPC

Java Servlet Technology

J2EE

JDBC

Java Server Pages

Java Message Service

Java Transaction API & Service JTA + JTS

SAAJ (Web Services) JavaMail API

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J2EE Application Components – J2EE applications comprises various components. •Client Components – Built using applets which runs on client machine •Web Compoents – Built using Java Servlet technology and JSP technology which runs on server. •Business Compnents – Built using EJB technolgy which runs on server. TCS Internal

September 3, 2009

Web Components •J2EE Web components can be either servlets or JSP pages •Servlets are Java programming language classes that dynamically process requests and construct responses. •JSP pages are text-based documents that execute as servlets but allow a more natural approach to creating static content

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September 3, 2009

Web Components (cont..) •Static HTML pages and applets are bundled with Web components during application assembly, but are not considered Web components by the J2EE specification. •Server-side utility classes can also be bundled with Web components and, like HTML pages, are not considered Web components.

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Web Tier

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Business Components •Business code, which is logic that solves or meets the needs of a particular business domain such as banking, retail, or finance, is handled by enterprise beans running in the business tier.

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Business Tier

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EIS Tier •The enterprise information system tier handles enterprise information system software and includes enterprise infrastructure systems such as enterprise resource planning (ERP), mainframe transaction processing, database systems, and other legacy information systems. •Related API’s – JCA , JDBC , JMS , Web Services etc

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J2EE Containers •What is a Container – Containers are the interface between a component and the low-level platform specific functionality that supports the component. •How does it work – Container settings are specified for each component during assembly process before deployment. •What do I get – Support for security, transaction management, JNDI lookup, Remote connectivity. TCS Internal

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J2EE Containers (cont..) –Manage life cycle of objects –Manage transactions –Provide security –Resource optimization •DB pooling •Compiled JSP Caching –Persistence support •CMP (EJB-QL) TCS Internal

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J2EE Roles & Responsibilities •J2EE Product Provider – Builds Compliant products • IBM Websphere •JBoss •Application Component Provider – Develops the application – jsp, servlet, ejb etc. •Application Assembler – Resolves dependencies, Deliver deployable app. TCS Internal

September 3, 2009

J2EE Roles & Responsibilities (cont..) •Deployer – Configures resources •DB, Roles, Users, etc. •System Administrator / Production Support – Runtime monitoring, Network administration, Support •Tool Provider – Provides helper tools for managing, deploying, developing, packaging. TCS Internal

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Reference •Stephanie Bodoff, et. al., The J2EE Tutorial, Sun Microsystems. •James Mc Govern, et. al., J2EE 1.4. Bible.

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September 3, 2009