Dynamic web page

A dynamic web page is a kind of web page that has been prepared with fresh information (content and/or layout), for each individual viewing. It is not static because it changes with the time (e.g. news content), the user (e.g. preferences in a login session), the user interaction (e.g. web page game), the context (e.g. parametric customization), or any combination thereof.

Properties associated with dynamic web pages

Classical hypertext navigation occurs among "static" documents, and, for web users, this experience is reproduced using static web pages, meaning that a page retrieved by different users at different times is always the same, in the same form.

However, a web page can also provide a live user experience. Content (text, images, form fields, etc.) on a web page can change in response to different contexts or conditions. In dynamic sites, page content and page layout are created separately. The content is retrieved from a database and is placed on a web page only when needed or asked. This allows for quicker page loading, and it allows just about anyone with limited web design experience to update their own website via an administrative tool. This set-up is ideal for those who wish to make frequent changes to their websites including text and image updates, e.g. e-commerce.

Two types of dynamic web sites

Client-side scripting and content creation

Using client-side scripting to change interface behaviors within a specific web page, in response to mouse or keyboard actions or at specified timing events. In this case the dynamic behavior occurs within the presentation.

Such web pages use presentation technology called rich interfaced pages. Client-side scripting languages like JavaScript or ActionScript, used for Dynamic HTML (DHTML) and Flash technologies respectively, are frequently used to orchestrate media types (sound, animations, changing text, etc.) of the presentation. The scripting also allows use of remote scripting, a technique by which the DHTML page requests additional information from a server, using a hidden Frame, XMLHttpRequests, or a Web service.

The Client-side content is generated on the user's computer. The web browser retrieves a page from the server, then processes the code embedded in the page (often written in JavaScript) and displays the retrieved page's content to the user.

The innerHTML property (or write command) can illustrate the client-side dynamic page generation: two distinct pages, A and B, can be regenerated as document.innerHTML = A and document.innerHTML = B; or "on load dynamic" by document.write(A) and document.write(B).

There are also some utilities and frameworks for converting HTML files into JavaScript files. For example webJS^[1] uses innerHTML property for rendering pages from converted HTML on client-side.

The first "widespread used" version of JavaScript was 1996 (with Netscape 3 an ECMAscript standard).

Server-side scripting and content creation

A program running on the web server (server-side scripting) is used to change the web content on various web pages, or to adjust the sequence of or reload of the web pages. Server responses may be determined by such conditions as data in a posted HTML form, parameters in the URL, the type of browser being used, the passage of time, or a database or server state.

Such web pages are often created with the help of server-side languages such as ASP, ColdFusion, Perl, PHP, and other languages. These server-side languages often use the Common Gateway Interface (CGI) to produce dynamic web pages. Two notable exceptions are ASP.NET and JSP, which reuse CGI concepts in their APIs but actually dispatch all web requests into a shared virtual machine.

Server-side dynamic pages can also use the first kind of dynamic content on the client side.

While VM-based server-side languages and CGI would be preferred for new development, some web-servers also support Server Side Includes (typically for a file extension such as .shtml), and Jhtml was a Java server-side technology developed before JSP.

Combining client and server side

Ajax is a web development technique for dynamically interchanging content with the server-side, without reloading the web page. Google Maps is an example of a web application that uses Ajax techniques and database.

Disadvantages

• Search engines work by creating indexes of published HTML web pages that were, initially, "static". With the advent of dynamic web pages, often created from a private database, the content is less visible^[2]. Unless this content is duplicated in some way (for example, as a series of extra static pages on the same site), a search may not find the information it is looking for. It is unreasonable to expect generalized web search engines to be able to access complex database structures, some of which in any case may be secure.

History

It is difficult to be precise about "dynamic web page beginnings" or chronology, because the precise concept makes sense only after the "widespread development of web pages": HTTP has been in use since 1990, HTML, as standard, since 1996. The web browsers explosion started with 1993's Mosaic. It is obvious, however, that the concept of dynamically driven websites predates the internet, and in fact HTML. For example, in 1990, before the general public use of the internet, a dynamically driven remotely accessed menu system was implemented by Susan Biddlecomb, at the University of Southern California BBS on a 16 line TBBS system with TDBS add-on.

See also

• Common Gateway Interface
• Deep web
• Rich Internet application
• Static web page
• TBBS
• Web template system

References

• "The Information Revolution", J. R. Okin. ISBN 0976385740. Ed. Ironbound Press, 2005. 350 pp.
• "Learning VBScript", P. Lomax. ISBN 1565922476. Ed. O'Reilly, 1997. sec. C13.

1. ^ http://code.google.com/p/webjs/
2. ^ http://www.hypergurl.com/articles/dynamic.html