Internet Applications

Notes for Chapter 19Digital Domain, 2 ed

E-Commerce

E-Commerce is rapidly emerging as an essential business strategy

E-Commerce has the following components Web interface on the client side backend databases on the server side scripts to enable the interaction of these

two

Client-Side Scripting in E-Commerce

Resides on the client machine (downloaded with the Web interface)

Creates client interactivity Collects data from the user Does preliminary analysis and validation on

user-supplied data Sends validated data to the server

Server-Side Scripting in E-Commerce

Resides on the server Accepts data from the client Uses that data to

search backend databases write to databases initiate credit card processes, etc.

Returns response data to the client

Client-Side Processing and DHTML

Dynamic HTML (DHTML) is a collection of technologies to make client-side

interactions better and more interactive is a bit of a misnomer – it is not an extension of

HTML DHTML is not standardized

different browser companies compete with their own DHTML features

as long as the “browser wars” persist, DHTML is unlikely to be standardized

Two important components of DHTML CSS (cascading style sheets) client-side scripting

Cascading Style Sheets (CSS)

Define styles for formatting and displaying information

provides for better Web site internal consistency makes Web site style modifications much easier

Three types of CSS inline embedded external applied with precedence: inline->embedded-

>external

Client-Side Scripting and Forms

Scripting works hand-in-hand with HTML forms HTML forms have built-in mechanisms for

soliciting and collecting user data Forms are a part of standard HTML Client-side scripts are used to take action on

the data collected before sending it to the server

Such scripts are invoked using the onSubmit event handler

Server-Side Scripting

Accepts data from client Often written in

CGI (Common Gateway Interface) actually an interface rather than a scripting language can be written in a number of different scripting

languages PHP: HyperText Preprocessor ASP (Active Server Pages – Microsoft)

Java Programming

Java is an object-oriented full-purpose (as opposed to scripting only) programming language

Java is noted for its excellent cross-platform capability

accomplished by first compiling into bytecodes bytecodes are machine-independent a given machine’s Java RTE (Runtime Environment)

then interprets the bytecodes into the appropriate machine language at run-time

Java applets are small Java programs designed specially for the Web

XML (eXtensible Markup Language)

XML is a very flexible language designed to facilitate exchange of information across the Web

It is actually a meta-language that allows the creation of domain specific markup languages

HTML is but one example of a language that could be created with XML

Languages especially designed for the exchange of financial information, medical information, graphical information, and mathematics are other examples of existing XML specifications

Summary

E-Commerce is rapidly emerging as an essential business strategy

E-Commerce has the following components Web interface on the client side backend databases on the server side scripts to enable the interaction of these two

Client-side scripts create client interactivity collect data from the user send data to the server

Server-side scripts accept data from the client use that data to access backend databases or other

server resources return response data to the client

Summary (cont’d)

Dynamic HTML (DHTML) is a collection of technologies to improve client-

side interactivity and Web site usability two important components of DHTML

CSS (cascading style sheets) client-side scripting

scripting works hand-in-hand with HTML forms Java is an object-oriented full-purpose (as opposed

to scripting only) programming language Java applets are small Java programs designed

specially for the Web

Summary (cont’d)

XML is a meta-language that allows the creation of domain specific markup languages

It is designed to facilitate exchange of information across the Web