Difference Between Server-Side And User View Programming

Sometimes it is desirable to have web pages that are dynamically generated from a database each time a user visits them, based on user login, or generated from the user's previous entries in a web form. The site owner usually wants to keep the data and logic of page generation hidden from the viewer, so a client-side script is not appropriate (since client-side scripts are text-based, embedded in the HTML page itself, and can only operate on data that is also embedded in the HTML page, they keep neither the data nor the program secret). So, the usual practice is to store data in a database program running on the web server (or perhaps a separate database server), and generate the HTML pages the viewer sees from programs or scripts also running on the web server.

These so-called "server-side" scripts and programs can be quite complex, and can be written in any programming language. When the web server receives a request (from the user's browser) for a particular page, it passes the request on to the server-side script or program, which could gather information from a database, read information entered by the user in forms, do text manipulations, or perform numerical calculations; the program then puts the result in HTML format. This end result is passed back to the web server, which sends it to the user's browser for display as a standard HTML page.

The most commonly-used database programs for web pages are MySQL and Microsoft SQLServer; some web pages also use Oracle, PostgreSQL, and other databases. And while server-side programs can be written in any language, the most common languages are PHP, Perl, and ASP/Visual Basic/C#; some server-side programs are also written in JSP/Java, C++, and other languages. Typically, a software developer is needed to write server-side scripts, but some pre-written scripts can be purchased or downloaded for use by less technical web designers (such as scripts for shopping carts, guest books, form-email, blogs, and forums).

There are also collections of server-side scripts known as "content management systems", which are pre-written scripts for managing web site content. My article on Web Programming Resources has a review of several content management systems.