Dynamic web pages

Author : DAOUDI Samir | Context : MSc Software Engineering – Internet Programming

The web field has seen major changes since last decade; Many technologies and tools have been designed to make the web what it looks like today. We can see nowadays very powerful web site allowing a great level of interaction and security with users and all these changes made our lives better.
Solutions that have been developed arround the web would never exist (or without the same efficiency and power) if great programming languages and additional scripting ones did not exist. So what is hidden behind this important web applications. A general overview of the flow between user and web server is important to describe before moving toward web development technics.
1st of all we should consider the web servers that are the 1st connection point from the end-users point of view; They connect to web servers that can deal with thousands of connections and queries simultanuously. Than, the web server sends back (after different manipulations) the HTML page to the users. If the page was a dynamic one, it gets rendered by the web server and the results sent as HTML. The web browser present the result (graphics and text) finally to the user.
The classic or static HTML pages have been covered earlier, so now let’s focus in dynamic ones.

What are the dymanic web pages?
The age of static web pages is over, for long time, the web was based on many simple static HTML web pages linked together (Ulman, 2003). However, today’s users expect web pages that are updated frequently and administrators are seeking for an easy to maintain and update. For these reasons and other, building web sites as a set of static pages is no longer acceptable. Dynamic web pages are the solution for all these concerns, in fact Dynamic pages can be defined as web pages that are generated by the web server when users require them and can also be changed by the interaction with users. These dynamic pages are a fundamental part of Web 2.0.
Dynamic web sites can also be defined as application rather than sites. They should:
– Respond to different parameters (eg. Time, version of the browser …etc.)
– Generally have interfaces where administrators can manage the content.
– Having a “memory”, allowing for user registration and log-in.
– Are easier to maintain and upgrade…etc. (Ulman, 2003).

Dynamic web pages programming languages
Two major dynamic programmig languages have taken the lead: PHP and ASP.
PHP stands for Personal Homepage Page, the name is a little bit ugly as it gives the impression that it is just dedicated for personal web sites. PHP is a scripting language that gives web sites a dynamic aspect as it allow for example :
– Sending feedback form a website to your mailbox.
– Uploading files from a web page.
– Generating thumbnails for large images.
– Files manipulations (I/O).
– Displaying and updating information dynamically.
– Connecting to dabases for data extraction and manipulation …etc. (Powers, 2010).

ASP stands for Active Server Pages, it was initially released in Nov 1996; It provides an easy way to create dynamic web pages. At that time, other languages were very popular as CGI and Perl, however, ASP quickly gained in popularity for the following reasons:
– Ease of data access.
– Ease of page design.
– Components Object Model (COM) interoperability.
– Relatively flat learning curve for many programmers (Smith, 2002).

Scripting languages
These particular programming languages have the particularity of supporting scripts which can be executed without compiling but are interpreted instead. Hence, what is exactly scripting?
“A script is program code that doesn’t need pre-processing (e.g. compiling) before being run. In the context of a Web browser, scripting usually refers to program code written in JavaScript that is executed by the browser when a page is downloaded, or in response to an event triggered by the user.” (Massieux, 2012).

The scripting languages are required for web pages to add a dynamic touch to these last, javascript has significantly improved the quality of web interactions and made a lot of nowadays applications possible. However, it is no the only available technic that we can use to get web pages behave like that. I personally had an experience with a web application that required a sort of form which should be dynamically updated depending on different choices. I knew later, that the best technic to use would be Ajax (JavaScript based), but at that time I had no idea about it and was really in a hurry, so I did not had enough time to learn any scripting languages. So I used a technic which is really obsolet and deprecated: The forms calls another page at each modification which forced me to create about 5 pages for the same form each one calls another, untill the form gets completely filled. I admit that this is not the smarter way to develop, but it worked at that time, and I re-wrote it couple of months later.