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Java and the Internet

Internet is based on the concept of network of computers. In a network, two or more computers can communicate with each other and exchange information and resources among themselves, by using certain hardware (like network interface card, modem, cables etc.) and software.

Different types of networks

(Local Area Network)
This network links individual computers within a premises or campus. LAN's are used in offices to transfer information from one department to other and to share resources like printer.

(Metropolitan Area Network)
This network covers a large area, may be area of a city.

(Wide Area Network)
It is a network, which covers wide geographical area connecting remote cities, countries and continents. Communication media that can be used for WAN can be telephone wires, underwater cables, electromagnetic waves propagating in free space or communication satellites. WAN's are usually public networks. Internet is an example of WAN.

The Internet

Internet began as a US government project. This early network was called as ARPANET. Slowly universities and research facilities also got connected to it. Eventually this collection of networks became the Internet. In 1991, Internet was allowed for commercial use.

The Web

World Wide Web is also called as WWW or w3. The web is the brainchild of Tim Berners-Lee, who proposed the web as a way for physicists around the world to collaborate using a networked information system based on hypertext. Hypertext allows you to navigate through networked resources, at the touch of a button. Let's look at some general concepts:

Is WWW same as the Internet?

World Wide Web is not same as the Internet. The Web is just:

  • A part of the Internet.
  • A way of getting around on the Internet.
  • An interface of the Internet.
  • An easy way of getting to where you are going on the Internet.
  • A huge collection of interconnected hypertext documents. Hypertext documents are simple text documents with links to other documents. Links are the elements of the hypertext documents that are often presented as underlined words or icons and cursor changes to the shape of hand when placed on the link. When a link is clicked, a new document (to which link was associated) is transported on the screen. The structure of hypertext documents is defined by a language called as HTML i.e. Hypertext Markup Language. 
Common Internet Jargon

(Hypertext Transfer Protocol)
It is a protocol used on the web to transfer HTML documents from one location to another. 
Web browser: 
This is a client program (program on your computer) and is used to view web pages and run applets on the web. The commonly used web browsers are Netscape Navigator, Internet Explorer, Cyberdog (for Macintosh computers), HotJava etc. 
Web site: 
HTML documents on the web are referred to as web pages. All the related web pages are linked together and maintained in a same file on the web server to form a web site. 
(Uniform resource locators)
It is an address of any web page or file on the Internet. It consists of a protocol, a hostname, a port (optional), path to resource, that is, a directory and a file name. For example,

Protocol part consists of the name of the protocol that the client will use to access and transfer a particular file. In the above URL, http is the protocol. Protocol name is followed by a colon : and two //. Hostname identifies the address of the host. The hostname consists of two or more parts separated by periods. Periods separate domain information from the host name. In the above example: is the hostname and www is the domain name. Port information in URL identifies the port number. It is optional. If you do not specify the port number, the browser will use a default value. Therefore, you do not need to specify port numbers in URL, unless connection has to be made to a port other than the default. The final part of the URL is the path to the resource i.e. this path generally follows the directory structure from the root to the file specified in the URL. In the above example of the URL, products/index.html is the path to the resource, where products is a directory and index.html is a file.

How are Java and the Internet related to each other?

Java is used to create fully interactive programs for the web. These interactive applications developed in Java for the web are called as applets. Java is the most secure programming language for developing applications for distributed environments like World Wide Web.

In order to get a big picture of Java’s features, you can read James Gosling testimony in the Microsoft Antitrust case from this URL: