cis 285 robinson winter 2005 cis 285 web application development with java cis 285 sinclair...

CIS 285 ROBINSON WINTER 2005

CIS 285CIS 285 Web Application Web Application

Development with JavaDevelopment with Java

CIS 285Sinclair Community CollegeInstructor: Mary Robinson


Course Objectives

Create attractive Web sites that include graphics, forms, tables & form validation

Understand the JavaScript/HTML Object model

Use Cookies to access Web applications Construct and use JavaServer Pages and

integrate Java Beans Construct and launch Java Servlets from

HTML and JavaServer Pages


Course Objectives

Use JDBC to retrieve, insert and update data in a back end database from a Web page

Generate dynamic Web pages using JavaServer Pages, JavaBeans, Java Servlets, JDBC and XML

Understand the model-view-controller (MVC) Design, create and deploy a small e-business

Web-site using all the tools taught in the class Introduce “Best Practices”


Course Progress

Class attendance Labs & Projects Assignments Exams Contacting the instructors


Introduction

Name and organization Object-oriented programming

experience HTML, XHTML, XML, JavaScript

background Java, WebSphere Studio Application

Developer or other IDE experience


Agenda – 4 Jan 2005

General Web Architecture Web Evolution Server-Side Technologies Servlet / Java Server Page (JSP) Lab Exercise (HTML) Lab Assignment


Class #1 Objectives:

Define the stages of Web application development

Discuss static content - HTML Dynamic content – client-side Dynamic content – server-side Create an HTML page Instructions for Lab #1


General Web Architecture

Web server requests a Web page from a Web server

Web server locates requested page Web server could process some code in the

requested page Web server send page to the client that

requested it


Client / Server Model

Data LayerDatabase

Legacy Store

BusinessLogic

Separates execution of tasks evenly (goal)

Makes optimal useof resources

Based on the distributionof the components, N-tierclient-server models havebeen developed

PresentationLogic


Two Tier Client / ServerArchitecture

DatabaseServer

Accesses databaseIssues queries

Return results to client

Presentation LogicBusiness Logic Database Management


Three Tier Client / ServerArchitecture

DatabaseServer

Presentation LogicDatabase

Management

ApplicationServer

Business Logic

Client Application Server Database

Send requestto application

server

Access databaseand issuequeries

Send anddisplay results

Business logicmanipulatesquery result


Web Application – Static

Server

Client

Web Browser

Web Server

File System

HTTP Request

HTTP Response

Network


Web Application – Static Pages

Content exists before the page is requested

User requests a page via URL into the browser, and the request is sent from the browser to the Web server via HTTP (HTTP request)

Web server receives the request (via HTTP) and locates the .htm /.html page in file system

Web server sends HTML stream (response) back across the Internet (via HTTP) to client browser

Browser interprets the HTML and displays the page


Web Application – DynamicClient-Side

Server

Client

Web BrowserJVM & JScript, JS

(Interpreters)

Web Server

File System

HTTP Request

HTTP Response

Network


Web Application – DynamicClient - Side

Content (some or all) does not exist before a page is requested

Content can be improved with client-side programs such as: JavaScript, VBScript, JScript, Applets

Browsers must provide the appropriate interpreter to execute scripting code (Browser Dependent)

All browsers come with built-in engines – not all have the same engines ( Ex. Netscape cannot interpret VBScript or JScript)

Examples: Current time on your system


Web Application – DynamicClient - Side 2

Notes on Applets: Have security constraints which restrict access to

back-end systems

Web browser (or JDK’s appletviewer) uses the HTML document to locate the applet’s byte code files on the Internet or the system’s hard drive

HTML file must contain an <applet> tag

Web browser will then load the JVM, which will load applet’s code into memory – interpret and execute it


Web Application – DynamicServer-Side

Server

Client

Web Browser

Web Server

File System

(URL) HTTP Request

HTTP Response

Network

Server-sideScript

Business Logic

Accessdatabase

Result

Result

Server-sideProgramDynamic ReqStatic Req


Web Application – DynamicServer - Side

Content (some or all) does not exist before a page is requested

Server-side scripts are executed on the server

Content can be improved with server-side programs such as: CGI, ASP, ASP.NET, JSPs (Servlets) – different ext.

Servers must be equipped with an engine that can interpret the corresponding scripting code

Server-side scripts have Nothing to do with client browsers


Server–Side Application NotesFor CGI, ASP & ASP.NET

CGI Compiled, runs fast Difficult to modify and update (recompile program) Not convenient to connect to database Security issues – poor code and tainting

ASP ASP script is contained within HTML tags Using Active control and DLL ASP script itself needs to be interpreted every time it is

requested

ASP.NET Overcomes drawbacks discussed above Limited support - primarily used on Windows platform


Web Application – ServletsServer - Side

ServerClient

Web Browser

Web Server Plug-in

Web Container

HTTP Request

HTTP ResponseWeb Server

File System

NetworkStaticResourceRequests

DynamicResourceRequests

DynamicResponse


Web Application: Servlets

Servlets are small Java programs that run on a Web server in response to client requests

Servlets generate dynamic content that is sent back to client

Servlets are compiled and represented as .class files

Servlets are loaded either on demand or by the server at start-up

When a servlet is requested from client, a method or function is called in response to the request


Web Application: Servlets

Once a servlet has been loaded, it remains in memory until the server decides to remove it or the server is shutdown.

A servlet is loaded either at start-up or upon the first client request to it, and after that, every time a client makes a request to the servlet, the server merely runs a method within the servlet. This dramatically reduces the response time experienced by client.

Servlets are completely written in Java.

Platform independent, server-side modules (components) that are download, on demand, by the system that needs these application components.


Web Application: Servlets Many major software vendors currently provide native support

for servlets and JSP within their product:

IBM WebSphere server

BEA WebLogic Application Server

Netscape Enterprise Server

Servlet and JSP engines:

JRUN from Live Software

ServletExec from New Atlanta Communications

Apache Tomcat from the Apache Software Foundation

Support many popular Web servers including Microsoft Internet Information Server (IIS) and Apache (HTTP)


Web Application – Servlets

ServerClient

Web Browser

Web Server Plug-in

Web Container

HTTP Request

HTTP ResponseWeb Server

File System

NetworkStaticResourceRequests

DynamicResourceRequests

DynamicResponse


Servlet Problem When a JSP page is requested, the first time, it is compiled into its

corresponding servlet

Servlets give poor separation between business logic and presentation logic

If this servlet is responsible for handling all corresponding requests and content from the browser, then the HTML and other content must be embedded in the Java code:

A Java editor must be used

Code must be produced by a Java developer

Application flow and presentation may be “colluded” - limiting reuse, maintenance becomes difficult, and parallel development may be limited or not even possible


Web Application: Servlet Problem

Web Container

Request

Response

Servlet

RequestDispatcher – not being utilized

service (req, res)

methods()

forward (req, res)

service (req, res)


Web Application Solution for Servlets – JSP Evolution

Web Container

Request

Response

Servlet

RequestDispatcher

JavaServer Page

JavaBean

service (req, res)

service (req, res)

methods()

forward (req, res)

methods()


JSP Benefits

Uses HTML / XML tags that encapsulate the logic that generates the content for the page

Application logic can reside on other servers – separation of logic from display

Formatting tags are passed to the response page

Can use JSP technology without having to learn the Java language – ease of administration


JSP Benefits

Separates the page logic from its design and display

Supports a reusable component-based design – Web-based applications can be built quickly

Extension of Java Servlet technology Platform independent, enhanced

performance, extensible and easy to use.


J2EE Architecture Diagram

Java 2 Platform Enterprise Edition Specification, v1.4 11/24/03 Shannon


Resources

http://www.w3.org/MarkUp/ http://www.w3.org/MarkUp/Guide/ http://validator.w3.org/ http://www.w3.org/TR/html401/index/elements.html http://java.sun.com/products/jsp/overview.html http://www.course.com/catalog/downloads.cfm?isbn=0-61

9-06343-2 http://www.brainopolis.com/jsp/book/jspBook_Architecture

s.html


Questions?

cis 285 robinson winter 2005 cis 285 web application development with java cis 285 sinclair...

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