Architecture of the web

Client Serverretrieved or generated web page

Activities on the Client

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 using a database (SQLite)•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

Activities On The Server

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

Activities On The Server

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-php5

mod-ruby

mod-cgi

jsp redirect

Operating System: port 80

n-Tier Client/Server

Apache or IIS Server

mod-php5

mod-ruby

mod-cgi

jsp redirect

Operating System: port 80

Database Server

Request

Response

Local DatabaseJSP Server

Interaction with the File System

Apache or IIS Server

mod-php5

Request for file

File or Error code

Request for Error Page

request fo

r inclu

de

or data file handle

File

hand

le

Request

Response

PHP FilePHP Output

Interaction with the Database

Apache or IIS Server

mod-php5

library

function ca

ll

Result Set, r

ecord count o

r errr

or code

Request with form data

Response

Client

Library function call (Java, VB) using sockets for communication

Result Set, record count or errror code