Introducing Web Development

One of the most popular server-side technologies used today for developing Web applications is ASP.NET.

WEB applications are programs that are executed on a Web server and accessed from a Web browser. These applications enable organizations to share and access information on the Internet and corporate intranets.

This information can be accessed from anywhere and at any time. In additions, Web applications can support on-line commercial transactions popularly known as e-commerce. An on-line store accessed through a Web browser is an example of a Web application.

A Web Application consists of Web pages. Web pages can be of the following types:

    • Static Web Page: A Web page that consists of only Hyper Text Language (HTML) is a static Web page. A static Web page does not respond dynamically to the actions performed by a user.

    • Dynamic Web Page: A Web page that responds dynamically to the actions performed by a user is a dynamic Web page and an application that consists of dynamic Web pages is a dynamic Web application. Such an application can be created by using server-side scripts, client-side scripts, or both in addition to HTML pages.

Server-Side Scripting

Server-side scripting is a technique used in website design which involves embedding scripts in an HTML source code which results in a user's (client's) request to the server website being handled by a script running server-side before the server responds to the client's request. The scripts can be written in any of a number of server-side scripting languages available (see below). Server-side scripting differs from client-side scripting where embedded scripts, such as JavaScript, are run client-side in the web browser.

Server-side scripting is usually used to provide an interface and to limit client access to proprietary databases or other data sources. These scripts may assemble client characteristics for use in customizing the response based on those characteristics, the user's requirements, access rights, etc. Server-side scripting also enables the website owner to reduce user access to the source code of server-side scripts which may be proprietary and valuable in itself. The down-side to the use of server-side scripting is that the server website computer needs to provide most of the computing resources before sending a page to the client computer for display via its web browser.

When the server serves data in a commonly used manner, for example according to the HTTP or FTP protocols, users may have their choice of a number of client programs (most modern web browsers can request and receive data using both of those protocols). In the case of more specialized applications, programmers may write their own server, client, and communications protocol, that can only be used with one another.

Programs that run on a user's local computer without ever sending or receiving data over a network are not considered clients, and so the operations of such programs would not be considered client-side operations.

What can Server Scripts Do?

Dynamically edit, change or add any content to a Web page

Respond to user queries or data submitted from HTML forms

Access any data or databases and return the result to a browser

Customize a Web page to make it more useful for individual users

Provide security since your server code cannot be viewed from a browser

Client Side Scripting

Client-side scripting generally refers to the class of computer programs on the web that are executed client-side, by the user's web browser, instead of server-side (on the web server).This type of computer programming is an important part of the Dynamic HTML (DHTML) concept, enabling web pages to be scripted; that is, to have different and changing content depending on user input, environmental conditions (such as the time of day), or other variables.

Client-side scripts are often embedded within an HTML or XHTML document (hence known as an "embedded script"), but they may also be contained in a separate file, to which the document (or documents) that use it make reference (hence known as an "external script"). Upon request, the necessary files are sent to the user's computer by the web server (or servers) on which they reside. The user's web browser executes the script, then displays the document, including any visible output from the script. Client-side scripts may also contain instructions for the browser to follow in response to certain user actions, (e.g., clicking a button). Often, these instructions

can be followed without further communication with the server.A Client Side script helps reduce network traffic because it does not need to interact with a Web Server to provide dynamic response to the user input. Scripting languages, such as VBScript and JavaScript, are used to write client-side scripts.