Web Application Concepts_updated.pdf

Web Application Development

Web Application Concepts

Objectives

• Discuss the concepts of web applications,

• Explain the web server application request

handling,

• Enumerate the Java web application technologies,

• State the web application life cycle, and

• Discuss web modules.

Web Application

• An application program that is stored on a

remote server and delivered over the

Internet through a browser interface

Dynamic vs. Static Content

• Dynamic Content – content-based generated based on program parameters, HTTP request and

responses and database queries

• Static Content – output produced for the consumer

is still the same. Typical representation is HTML

Java Web Application Request and Response Handling

Java Web Application Request and Response Handling

Servlets and JSP

• Servlets – Java classes that dynamically process

requests and responses

• JSP pages - text-based documents that execute as

Servlets but allow a more natural approach to

creating a static content

Web Container

Web Container Concepts

• Services that provide for web components

(request dispatching, security, concurrency

and life-cycle management)

• Give access to APIs such as naming,

transaction and email

Web Application Life Cycle

Web Application Life Cycle – Composition

Web components

Static resource files

Helper classes

Libraries

Web Application Life Cycle

• Development the web component code

• Develop the web application deployment

descriptor

• Compile the web application components and

helper classes referenced by the components

Web Application Life Cycle

• Optionally package the application into a

deployable unit

• Deploy the application into a web container

• Access a URL that references the web

application

Web Modules

Web Module Application – Document Root

JSP Pages

Client-side classes and

archives

Static web resources

(images, etc)

Web Application - WEB-INF

• web.xml – web application deployment

descriptor

• Tag library descriptor files

• classes – directory that contains server-side

classes: servlets, utility classes and JavaBeans

components

Web Application - WEB-INF

• tags – a directory that contains tag files,

which are implementation of tag libraries

• lib – a library that contains JAR archives of

library called by server-side classes

Web Application

Looking Back

• Discussed the concepts web applications

• Explained the web server application request

handling

• Enumerated the Java web application

technologies