1. Architecture of the web
Client
Request
Server
Response
retrieved or generated web page

2. Activities on the Client
Generate a request
Manage loading of web content
Translates Web Pages into DOM
Render HTML, CSS, Images
Renders SVG Graphics
interpret JavaScript, VBScript
Manipulate the DOM using JavaScript, VBScript
Stores Cookies, Bookmarks, History, Form Data and local datastores
AJAX requests using JavaScript, VBScript
Maintains “sandbox” security (SOP, CORS)
Interprets XML+XSLT
A container for video and audio codecs
A container for Java Applets
Client

3. Activities On The Server
Listens for Requests
Loads modules in mods-enabled
Translates directory refs in sites-enabled (root directory for system and per-user web accounts)
Moves uploaded files into /tmp
Passes QUERY_STRING, par
Sends the output of the following
Requests files from the OS
Returns error page if the file is not found
Requests execution of CGI scripts by the OS
Interprets PHP
Logs web page access and errors
Requests JSP (Java) execution from a secondary server
Server

4. Activities On The Server
Operating System: port 80
The Server DOES NOT talk directly to an SQL Database Engine!!! Communication with a database is done either through the PHP-MYQL library or through a library in some other server based language such as Java, Python, Ruby, PERL or some variation of C. All of the above can also talk to the OS to read and write files. The database does not have to be resident on the same machine
CSS, Script, Images or other included files in a web page are loaded by the Client, NOT the server.
Apache or IIS Server
mod-php
mod-ruby
mod-cgi
jsp redirect

5. n-Tier Client/Server Request Response Database Server JSP Server
Apache or IIS Server
mod-php
mod-ruby
mod-cgi
jsp redirect
Operating System: port 80
Request
Response
Local Database
JSP Server

6. Interaction with the File System
Request for file
Request
Apache or IIS Server
File or Error code
Request for Error Page
PHP File
request for include or data file handle
PHP Output
Response
File handle
mod-php

7. Interaction with the Database
Library function call (Java, PHP) using sockets for communication
Client
Result Set, record count or errror code
library function call
Apache or IIS Server
Request with form data
Result Set, record count or errror code
mod-php
Response