Week6: Apache

Apache is the most popular choice for web servers on the Net with almost 50% of all machines running it. Released under its own license, the Apache HTTP Server software is released freely.

Uses

Apaches main usage is to handle incoming requests and pass them on to the relevant handle, this is typically a URI mapped to a file location. However it can also use various rewrite directives, typically mod_rewrite, to map a location to different locations to aid in the production of SEO amongst other things.

Apache can also handle a large array of dynamic scripting languages through the use of various libraries. Typically Apache can run PHP, Python, Perl and Ruby on Rails amongst others.

Finally, virtual hosting allows one installation of Apache to serve multiple websites which is used by shared hosting providers. With virtual hosting a single machine running Apache can provide the web serving capabilities for www.example.com, www.example2.co.uk and www.subdomian.example.com simultaneously.

Static & Dynamic

Web pages fall under two categories when served. A static page (normally HTML) is a file which contains plain text and does not change between requests. These pages are small and quickly served as no further action needs to be taken by the web server.

Dynamic pages are pretty much what they sound like, the content they display changes. This can be based on user input i.e. search terms, database content or even something as simple as time of day. Depending upon the complexity of the script the time needed to generate a dynamic page can range from a few milliseconds to several seconds (typically web servers have a timeout limit to prevent pages running for excessive amounts of time). Dynamic pages are intrinsically slower than static pages however through the use of caching this difference can be reduced.