12-06-2012, 03:51 PM
INTRODUCTION TO DEVELOPMENT OF DYNAMIC WEB APPLICATIONS
DYNAMICWEBAPPLICATIOS.pdf (Size: 1.98 MB / Downloads: 131)
Introduction
Web-pages and web sites
The Internet was initiated in the 1970's as a further development of the ARPANET. The World Wide Web, WWW, was developed and introduced in 1989 by Tim Berners-Lee and Robert Cailliau at the European Particle Physics Laboratory (CERN) as an Internet tool for collaborative knowledge-sharing. It became in short time very popular. Today, the WWW comprises a large number of computers that make files available through the Internet according to the HyperText Transfer Protocol, HTTP. Today, it is estimated that more than 250 M people worldwide are using the web.
CGI and PERL
The first step towards dynamic web pages is the possibility for a remote client to request the execution of a process at the host. Use of the FORM tags of HTML requires for example that the server can perform a processing of the data submitted on the form. A program must exist for this purpose at the host site, and the web server must be able to communicate with this program. We will refer to such a program as a script, and the addressable files in which the script is stored as templates to avoid any confusion with other types of programs, files, and pages.
ColdFusion Markup Language
The most well-known API tools include the Active Server Pages, ASP, and ASP.NET from Microsoft, the open source system PHP: Hypertext Preprocessor, PHP, Inline Internet Systems, iHTML, and ColdFusion MX, CFMX, from Macromedia. We are leaving the comparisons between the tools to evaluators and sales people, and concentrate on CFMX in this course because it is well developed, easy to learn, and reliable.
Evaluating a web site
Before starting to improve a web site, you should try to make an evaluation of its performance. Evaluating a web application requires empirical data. The most obvious source is the log of the activities of the web server. The first step towards collecting data on the use of pages was counting the number of visitors to the web site. The number of visitors tells the owner of the site if his/her site was visited at all, and how frequently. In most web servers, an access log system is embedded. The access log system continuously records all requests to the server as well as the server's retrieval of different files to compose the responses. A log, even for a completely static web site, gives data on dynamic development because it reflects visits during a time interval.