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e-business Application Development

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J2EE vs .Net

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Benefits of J2EE

Simplified architecture and developmentƒ Variety of standard services, components, and clientsƒ Choices of toolsƒ Portabilityƒ Integration with existing information systems

Separation of Responsibilities

Scalability

Flexible security model

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API AppletApplication

ClientWeb EJB

JDBC 2.0 N Y Y YJTA 1.0 N N Y YJNDI 1.2 N Y Y YServlet 2.3 N N Y NJSP 1.2 N N Y NEJB 2.0 N Y1 Y2 YRMI-IIOP 1.0 N Y Y YJMS 1.0x N Y Y YJavaMail 1.2 N N Y YJAF 1.0x N N Y Y

J2EE 1.3 Required Standard Extension APIs

1 Application clients can only make use of the enterprise bean client APIs.2 Servlets and JSP pages can only make use of the enterprise bean client APIs.

J2EE Technologies Summary

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HTML documentƒ Embedded JSP specific tagsƒ Inline Java Code

On the server, JSP Page is parsed and compiled into a Java Servlet

WebSphere 5.0 fully supports JSP1.2

Server Side Component - JSP

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Server-Side Components - Servlets

Servlets are Java classes that allow application logic to be embedded in HTTP request-response process.

J2EE 1.3 requires:ƒ Servlet 2.3 specification

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J2EE Services: JDBC

Provides database-independent connectivity to a variety of data stores

J2EE 1.2 specifies:ƒ JDBC 2.0 Core APIs - Basic database servicesƒ JDBC 2.0 Extension APIs - Advanced functionality

Connection PoolingTransactional capabilities

Functionality provided by a combination of WebSphere and a compliant JDBC driver

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Application Servers:Work with Web server to manage browser and Java based client sessionsSupport server-side business logic (Servlets/JavaServer Pages/EJBs)Connect to back end computing resources for data and transaction processing

Application server benefits:Simplify development and deployment of web-enabled e-business applicationsSupport connections to legacy data and applicationsDeliver a set of application deployment and management tools

Application Serving

Transaction Serving

Active Business Rules

Web Server

Business Applications

App Server

Client

Page Serving

User Interfac

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Transactions

Application Servers

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Model-View-Controller architecture

Reduce the programming effort required to build and maintain systems

Separate the application into 3 distinct layers

Controller - application flow

Model - business logic

View - the output

Models, Controllers, and the views are treated as separate entities

Changes can be made independently

Different people/skills can work independently

WebSphere Application ServerWebSphere Application Server

/JSP

Model 1

Model 2

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Software

• HTTP Servers– Apache HTTP Server (Open Source)– IBM HTTP Server powered by Apache– Many others

• Some Application Servers– Jakata Apache (Open Source)

• Tomcat

– IBM WebSphere Application Server– BEA Weblogic– Sun iPlanet– And more

• Comparable MS support– IIS (Internet Information Services)

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WebSphere Application Server - Express

• An offering from IBM that contains:– WebSphere Application Server– WebSphere Studio Site Developer– IBM Agent Controller

• Tools to build and deploy J2EE compliant applications

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Site Developer ExpressApplication Server

Applicationserver- JSPs- Servlets

Web server-HTML-images

Webprojects

ExpressTestEnvironment

Develop

deploy

Data Access -DB2 -Oracle -SQL Server -Cloudscape

WebClient

WebSphere Application Server Express

Agent Controller

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Perspectives

There is a perspective for each of the different roles in a development life cycle (some roles overlap)

Open different perspectives by ƒ Perspective>Open>Otherƒ Selecting Open Perspective Button

To switch between perspectives use: shortcut bar

A group of related views and editors is called a perspective

Configurable

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Perspective/Project, What's the difference?

Projects - a grouping of resources

Perspectives-multiple views of assets in workbench providing tools to help with task

Perspectives are different ways of looking at the same project

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Perspectives are made up of views

Display a view by selecting Perspective > Show Views

Views support:

ƒ Editors ƒ Provide alternative presentations or navigation of the

information A view might appear by itself, or stacked with other views in a tabbed notebook

Views can be floated by Selecting the blue bar at the top of the Tasks view and drag it on to the desktop.

Views

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Web Application

• Defined in J2EE and Java servlet specification• Standardized format which is compatible between

multiple vendors• Contains:

– JavaServer Pages

– Servlets

– Applets

– HTML and XML files

– Meta information to connect elements• Deployment descriptor

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XML-based files describing the environment for modules and its componentsƒ Each module and ear file has a deployment descriptor

Can be automatically created and verified by WebSphere's deployment toolƒ Application Assembly Tool (AAT)

Can be manually created or edited

J2EE: Deployment Descriptor (DD)

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Running the Application

• Need to create an application server

• Site Developer will create one for you– HTTP Server– Application Server

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Site Developer ExpressApplication Server

Applicationserver- JSPs- Servlets

Web server-HTML-images

Webprojects

ExpressTestEnvironment

Develop

deploy

Data Access -DB2 -Oracle -SQL Server -Cloudscape

WebClient

WebSphere Application Server Express

Agent Controller

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Web Pages

• Static– Constant information– Can only be changed by changing the html page

• Dynamic– Information changes – Database access– May be customized for individual end user

• Personalization

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Creating an HTML Page

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HTML Editor

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Framesets

header.html

main.htmlmenu.htmltoggle

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Frameset source

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Setting attributes

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Using tables

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The completed table

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Adding Links

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Cascading Style Sheet

• A file that defines a hierarchical set of style rules that the creator of an HTML or XML file uses in order to control how that page is rendered in a browser or viewer, or how it is printed. 

• A CSS includes a defined order of precedence to address cases when the definitions of any style element in a document conflict. 

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Cascading Style Sheets

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Set Style Properties

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WebArt Designer

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Common Database Models

• Relational– Stores data in a database consisting of one or more

tables of rows and columns

• Object – Combine the elements of object orientation and

object-oriented programming languages with database capabilities

– Support additional data types (complex types)

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Relational Model Concepts

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SQL• Structured Query Language• Provides a standard language to access relational

databases• Works with most common database systems

– Microsoft Access, IBM DB2, Oracle, Informix, MS SQL Server

• SQL statements can be used to manipulate a database– Define a database– Define tables– Define columns and their characteristics

• SQL can be used to request rows from a database• SQL can be used to add, update and delete rows

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Middleware

• A layer of software between your application and the database

• Provides a standard interface to any DBMS

• Examples:– ODBC – Open Database Connectivity

• Microsoft Products like Visual Basic

– JDBC – Java Database Connectivity• Java

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Benefits of Middleware

• The same object code can be used to access different DMBS products

• The application is independent of the data communications protocol

• Data can be handled in a format convenient to the application

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JDBC

• JDBC provides standard Java interfaces to access databases

• It is based on ODBC and supports a subset of what ODBC supports

• Database definition and manipulation is done using SQL statements

• JDBC is useful because it implements a standard interface

• It can theoretically work for accessing any database• A JDBC driver provides a database specific connection

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Some JDBC Drivers

• JDBC Driver provides access to a specific database– COM.ibm.db2.jdbc.net.DB2Driver

• Driver from IBM for accessing DB/2 across a network

– COM.ibm.db2.jdbc.app.DB2Driver• Driver from IBM for accessing DB/2 locally

– sun.jdbc.odbc.JdbcOdbcDriver• Driver from Sun for accessing databases supported by ODBC

• ie, MS Access

– oracle.jdbc.driver.OracleDriver • Driver to access Oracle databases