Web Applications

World Wide Web

Is the name given to the collection of information that has grown up on computers connected to the Internet and which is made available for anyone to access.

Features

• Written using HTML programing language
• Viewed using web browser
• contains HYPERTEXT which provides the user with clickable links

It is a network of computers, each communicating with several other computers in the network.

It is a world-wide communication system linking computers in geographically separate locations through the use of a variety of telecommunication links such as telephone lines and satellites.

A URL is a reference to the address of a resource on the Internet.

An example of a URL which addresses the CCEA website is: http://www.ccea.org.uk.

Hypertext Transfer Protocol is an application protocol used on the world wide web. It defines how data is structured and transmitted and specifies how browsers and web servers should act in response to requests.

This represents a standard set of rules used to ensure the proper transfer of information between computers on the Internet. They define how data is to be structured and what control signals are used. Every device linked to a network using the TCP/IP protocol is identified by a unique IP address. The IP address allows messages and data to be routed to the correct address on the network.

IP addresses can be:

Static – a permanent IP address that does not change.

Dynamic – temporary addresses that are assigned each time a computer accesses the Internet.

Computers identify websites by their IP address.

This software allows users to view and use the web pages on the Internet.

It is responsible for requesting the text and graphics of webpages from servers on the Internet, and assembling them for display.

These are usually in HTML format. Web browsers can be used to view any HTML pages whether users are online or offline.

A computer designed to deliver internet webpages across the internet or within an intranet. It processes requests for information that comes from the internet infrastructure. The web server contains applicatin software to enable the transmission of content and makes use of client-server technology.

In client-server technology, the program that accesses the application is called the client. This could be the browser. The program that provides the application is called the server.

In order to have an internet presence a web hosting service is required. this service provides individuals and organisations with access to a web server and web space to store a website or webpages. the web host company will ensure that the website is available online and the service may include: web space to store the website, an email feature, an interface for managing the wbsite online, customer support.

File Transfer Protocol - is the most common protocol used to transfer files across the Internet between client and server devices.

An Internet Service Provider - has direct links to the Internet and accepts transmission fromusers over communication lines and passes these onto the internet. The ISP sells Internet access to companies or individuals and provides acces to web servers which connect to the search engines on the internet. An ISP will provide the user with a range of services.

Typical services provided by an ISP include:

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