Web protocols and applications
Dynamic web pages
Original web pages were static in that they rarely changed in terms of their content and the same content was delivered to every user. Modern websites, on the other hand, change frequently and deliver different content to different users.
As such, the use of static content is seen as being labour intensive and costly today compared with the dynamic, ever-changing content of modern sites.
A good example of a static web page is this 1997 news story from the BBC. If you take a look, notice how small the images are to suit the typical bandwidth available at the time, and the absence of tickers or any other kind of animation or dynamic content. | BBC News | Single currency | Emu timetable: a single European currency by 2002?
Some large websites have so much content on offer that it is impractical to have a unique page for every article. To get round this issue, the website will typically consist of a generic template page, a CGI script and a large database.
When a visitor requests a page from the server, certain parameters are passed from the browser to the server (usually in the form of a cookie) and are fed into the Common Gateway Interface (CGI) script. This script processes the data and possibly interacts with content held in a database to produce a unique set of HTML items that are placed back into the template page. It is this finalised page that is delivered back to the end user as their webpage.
CGI scripts can be written in any of the different programming languages available, but the most common language used is PERL. Scripts written in this language have a .pl extension and can be loaded onto any web server platform. The resultant web page that is produced as a result of a CGI script usually has the file extension .asp or .php.
The .asp file extension is indicative of the Microsoft Active Server Page module being installed on the web server, which would indicate that the web server is more than likely the Microsoft Internet Information service (IIS). Some websites return .aspx files as a result of the CGI script. This indicates that the newer ASP.NET framework has been used to create the file.
The .php extension indicates that the PHP: Hypertext Preprocessor processor module is installed on the web server and that this may mean that the web server is Apache, although this is not guaranteed as the PHP module can be installed on Microsoft’s IIS web server.
Another server-side technology akin to both .asp and .php is Java Server Page (jsp). Developed by Sun as a rival to the other two technologies, jsp is a collection of JAVA servlets that reside on the web server and create output files in either HTML or XML.
As the name describes, a hybrid webpage is one where some browser-side elements are placed alongside server-side content and are delivered as the webpage.
Many modern webpages are hybrids that collate HTML and other content elements from numerous places via a script and then package it up to be delivered to the end user.
One way for websites to gain revenue is from hosting advertising space in their web pages. The adverts that fill these spaces are hosted on separate servers and are called whenever the page is requested by a user. Modern web sites utilise clever coding to provide these advertisement servers with detailed information so that relevant adverts are embedded in the pages you view.
This 2017 web page from the BBC, through the story of the development of their own website over the 20 years since its launch in 1997, tells a great story of how the World Wide Web has developed. Why not take a look around and see how the website has changed even since this story was published? | How the BBC News website has changed over the past 20 years - BBC News |
In this Course, you’ll further explore the web protocols that underpin the internet and the world wide web, and some of the applications they enable.
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