URL and Port

URL

Uniform Resource Locator - It is the unique address of each resource on the web.
It is in the format:

protocol:// server : port/path of the resource/resource name/[optional query string]

eg: http://www.freshfruits.com/all/fruits/grapes.jsp

Protocol (http):- tells the server which communication protocol is used
Server (www.freshfruits.com) :- the unique name of server which maps to a unique IP address.
IP address is numeric.
Port (80):- port number is optional. By default the port number for web server is 80
.
Path (all/fruits/) :- the location of the resource in the server
(unix syntax is used to describe the path)
Resource name (grapes.jsp) :- the requested resource
Optional query string:- the extra info in the GET request is appended to the end of URL as query string.
It starts with ? followed by name/value pair separated by &


TCP Port

A 16 bit number that identifies a specific softare program on the server hardware. It is a logical
connection to a software running on a server harware. A server has 65536 ports ranging from 0 - 65535.
The port numbers from 0-1023 are reserverd for system services.
It is possible to run different applications on the same port provided the applications are using different
protocols.
Some reserved ports:
21 - FTP
23 - Telnet
25 - SMTP
37 - Time
80 - HTTP
110 - POP3
443- HTTPS
Apache (the open source web server )directory structure:
Apache_home -> htdocs -> index.html, root folders for the apps on the server -> sub folders and htm pages