Application Architectures - The Practice of Cloud System Administration - page 68

Figure 4.1: Single-machine web service architecture
The web server generates web pages from three different sources:
• Static Content: Files are read from local storage and sent to the user unchanged.
These may be HTML pages, images, and other content like music, video, or down-
loadable software.
• Dynamic Content: Programs running on the web server generate HTML and pos-
sibly other output that is sent to the user. They may do so independently or based
on input received from the user.
• Database-Driven Dynamic Content: This is a special case of dynamic content
where the programs running on the web server consult a database for information
and use that to generate the web page. In this architecture, the database software
and its data are on the same machine as the web server.
Not all web servers have all three kinds of traffic. A static web server has no dynamic con-
tent. Dynamic content servers may or may not need a database.