URL&

protocols

URL

A Uniform Resource Locator (URL) is a standard way developed to specify the location of a resource available electronically.

RFC 1738

URL

What are URLs? • URLs make it possible to direct both people

and software. • A URL is like your complete mailing

address: • In short, a URL is a very convenient way to

direct people to a file or other electronic resource.

• URLs assist your exploration of the Internet.

John Brown12 Stoke RoadStoke-on-Trent ST4 2DG

• Uniform Resource Locators (URLs) • http://news.bbc.co.uk/1/hi/education/5341426.stm

URL

General URL syntax

<scheme>:<scheme-dependent-information>

Scheme examples:– http (hyper text transfer protocol)– ftp (file transfer protocol) – news (news protocol)

URL

Scheme Dependent Information<scheme>:<scheme-dependent-information>

– The information is detailed with each scheme – Machine is used for making the file available

– "Path" provides the information

– Example (for HTTP):

http://www.7sport.net/7sport/index.htm

Machine Path

Scheme

URL

URL Example (explained)

http://www.7sport.net/7sport/index.htm

Machine Path

Scheme

• http is the scheme hyper text transfer protocol

• two slashes (//) separate the scheme from the machine/domain name

• www.7sport.net is the machine/domain name• single slash (/) separates the name from the path• Finally 7sport/index.htm is the path.

URLHTTP URL Example (explained)

http://www.w3schools.com/html/html_forms.asp

Machine/Domain Name Path

Scheme

• http is the scheme hyper text transfer protocol

• two slashes (//) separate the scheme from the machine/domain name

• www.w3schools.com is the machine/domain name• single slash (/) separates the name from the path• Finally html/html_forms.asp is the path.

URL

Troubleshooting URLsReasons for not being able to access URLs:– the remote machine refuses the

connection– the site is very busy (e.g. peak hours of

use)– you have misspelled the URL– the file was moved

Protocol

In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing endpoints.

IP

Internet Protocol is a protocol which is responsible for addressing and packet routing between networks.

TCP

Transmission Control Protocol basically ensures that the packets get to their destination in the current sequence and without error.

FTP

File Transfer Protocol is a network protocol used to exchange and manipulate files over a TCP computer network, such as the Internet.

POP3

Post Office Protocol version 3 is an application-layer Internet standard protocol used by local e-mail clients to retrieve e-mail from a remote server over a TCP/IP connection.

SMTP

Simple Mail Transfer Protocol is an internet standard for e-mail transmission across internet protocol (IP) networks.

PPP

Point-to-Point Protocol, or PPP, is a data link protocol commonly used to establish a direct connection between two networking nodes. It can provide connection authentication, transmission encryption privacy, and compression.

Telnet

Telecommunication network is a network protocol used on the internet or local area networks. It provides access to a command-line interface on a remote machine.

HTTP

Hypertext Transfer Protocol is an application-level protocol for distributed, collaborative, hypermedia information systems. Its used for retrieving inter-linked resources led to the establishment of the world wide web (www).