Fundamentals of Internet and Java Programming-1

Introduction

Internet is the world's largest computer network, the network of networks, scattered all over the world. It was created nearly 25 years ago as a project for the U.S. Department of Defence. Its goal was to create a method for widely separated computers to transfer data efficiently even in the event of a nuclear attack. From a handful of computers and users in the 1960s, today the internet has grown to thousands of regional networks that can connect millions of users. Using internet, organisations all over the world can exchange data, people can communicate with each other in a faster and effective way. With the help of video conferencing over the interent, it has become possible that people can even see each other while they are communicating. Even one can do all his shopping sitting back at home. He does not bother to visit crowded market place for wasting his valuable time. Gradually, shopkeepers are also interested to opt for electronic commerce which provides them greater reach, faster and better ways to do business over the internet. Don't get surprised, if tomorrow you come to know that the paanwalla in your locality has started selling his paan over the internet. Thus, the internet has thrown up a number of technological challenges like using the net for secure, private and fast communication as well as supporting video and 3D graphics. Given this scenario of the internet, there was an implicit need to come up with a programming language to enable authors to incorporate
program application fragments (applets) into the web document. Finally this gave birth to Java programming language. We will discuss about this language in detail in later part of this lesson.

Internet - The History

In 1969, the U. S. Defence Department funded a project to develop a network, which can withstand the bombing. Basically the idea was to develop a very secured network which can work even after a nuclear attack. This project was known as ARPANET. The proposed network was not supposed to have a central control-which would be an obvious target. Ten years of research brought Local
Area Networks (LANs) and workstations were developed to get connected to LAN. These workstations and LANs were then connected to the ARPANET. For next decade the ARPANET grew and its decentralized features helped its rapid expansion. Computers connected to ARPANET used a standard or rule to communicate with each other. This standard used by ARPANET is known as
NCP (National Control Protocol). Protocol is a network term used to indicate the standard used by a network for communication. But the passing time and rapid change in information technology suppressed NCP and brought TCP/IP (Transmission Control Protocol/Internet Protocol) into the world of networking. TCP converts messages into streams of packets at the source, and they are
reassembled back into messages at the destination. Internet Protocol handles the dispatch of these packets. IP handles the addressing, and makes sure that a packet reaches its destination through multiple nodes and even across multiple networks with multiple standards. This flexibility of TCP/IP to handle multiple protocols encourages other networks to get connected to ARPANET. Slowly the
ARPANET became a massive network of networks and now it is known as 'Internet'. Internet is termed by some people as the world of largest democracy with no government. It has no state head to control it. Why do people want to get connected to Internet? May be because of the freedom it provides. The internet is a rare example of a large democracy with no head of state, no official censors, no bosses, no board of directors. Nobody controls the Internet and in principle, any computer can speak to any other computer, as long as it obeys the technical rules of the TCP/IP protocol. This freedom of Internet helped it to move out of its original base in military and research institutions, into elementary and high schools, colleges, public libraries, commercial sectors even into the shop of a vegetable vendor.

Services of Internet - E-mail, FTP, Telnet, WWW

But what does one do with the Internet? May be four things basically mail, discussion groups, long-distance computing, and file transfers. Internet mail (e-mail or electronic mail) is much faster as compared to normal postal mail. One can also send software and certain forms of compressed digital image as an attachment. News groups or discussion groups facilitate Internet user to join for various kinds of debate, discussion and new sharing. Long-distance computing was an original inspiration for development of ARPANET and does still provide a very useful service on Internet. Programmers can maintain accounts on distant, powerful computers which execute programs. File transfers
service allows Internet users to access remote machines and retrieve programs, data or text.

(a) E-Mail (Electronic Mail)
E-mail or electronic mail is paperless method of sending messages, notes or letters from one person to another or even many people at the same time via the Internet. E-mail is very fast compared to the normal post. E-mail messages usually take only few seconds to arrive at their destination. One can send messages anytime of the day or night and it will get delivered immediately. You need not have to wait for the post office to open and you don't have to get worried about holidays. It works 24 hours a day, seven days a week. What's more, the copy of the message you have sent will be available whenever you want to look at it even in the middle of the night. You have the privilege of sending something extra even such as a file, graphics, images etc. along with your e-mail. The biggest
advantage to using e--mail is that it is cheap, especially when sending messages to other states or countries and at the same time it can be delivered to a number of people around the world.
Although e-mail is faster and cheaper, it has many of the components of regular mail. It allows you to compose note, get the address of the recipient and send it. Once the mail is received and read, it can be forwarded, replied. One can even store it for later use, or delete. In e-mail even the sender can request for delivery receipt and read receipt from the recipient.

(i) Features of E-mail

• One-to-one or one-to-many communication
• Instant communication
• Physical presence of recipient is not required
• Most inexpensive mail service, 24-hours a day and seven days a week
• Encourages informal communication

(ii) Components of an E-mail Address

As in the case of normal mail system, e-mail is also based upon the concept of a recipient address. The e-mail address provides all the information required to get a message to the recipient from anywhere in the world. Consider the following e-mail ID
john@ hotmail.com

In the example above, "john" is the local part, which is the name of a mailbox on the destination computer, where finally the mail will be delivered. Hotmail is the mailserver where the mailbox "john" exists,.com is the type of organisation on net, which is hosting the mail server.
There are six main categories;

.com Commercial institutions or organization
.edu Educational institutions
.gov Government site
.mil Military site
.net Gateways and administrative hosts
.org Private organizations

(b) FTP (File Transfer Protocol)

File Transfer Protocol, is an Internet utility software used to upload and download files. It gives access to directories or folders on remote computers and allows software, data and text files to be transferred between different kinds of computers. FTP works on the basis of the same principle as that of Client/Server. FTP client is a program running on your computer that enables you to talk to and get stuff from remote computers. The FTP client takes FTP commands and sends them as requests for information from the remote computer, known as FTP servers. To access remote FTP server it is required but not necessary to have an account in the FTP server. When the FTP client gets connected, FTP server asks for the identification in terms of User Login name and password of the FTP client. If one does not have an account in the remote FTP server, still he can connect to
the server using anonymous login. This has been properly shown in Fig. 6.1 Using anonymous login anyone can login to a FTP server and can access public file archives, anywhere in the would, without having an account. One can easily Login to the FTP site with the username anonymous and e-mail address as password.
The basic objectives of FTP are l to give flexibility and promote sharing of computer programs, files and data.

• to transfer data reliably and more efficiently over network.
• to encourage implicit or indirect use of remote computers using Internet.
• to shield a user from variations in file storage systems among hosts.

The basic steps in an FTP session are:

• Start up your FTP client; by typing ftp on your system’s command line c;\>’ prompt (or, if you are in a Windows, double-click on the FTP icon).
• Give the FTP client an address to connect to. This is the FTP server address to which the FTP client will get connected.
• Identify yourself to the FTP remote site by giving the Login Name
• Give the remote site a password l Remote site will verify the Login Name/Password to allow the FTP client to access its files.
• Look directory for files in FTP server
• Change Directories if required
• Set the transfer mode (optional);
• Get the file(s) you want; and
• Quit

(c) Telnet (Remote Computing)

Telnet or remote computing is telecommunication utility software, which uses available telecommunication facility and allows you to become a user on a remote computer. Once you gain access to the remote computer, you can use it for the intended purpose. The TELNET works in a very step by step procedure. The commands types on the client computer are sent to the local Internet Service Provider (ISP), and then from the ISP to the remote computer that you have gained
access. Most of the ISP provides facility to TELNET into your own account from another city and check your e-mail while you are travelling or away on business.
The following steps are required for a TELNET session

• Start up the TELNET program;
• Give the TELNET program an address to connect to
• Make a note of what the "escape character" is;
• Log in to the remote computer;
• Set the terminal emulation;
• Play around on the remote computer; and
• Quit.