Introduction to network programming pdf

In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout.

Networks may be classified based on the method of data used to convey the data, these include digital and analog networks. Common layouts are: 1 Bus Network: all nodes are connected to a common medium along this medium. Internet History In ARPA university and private sector contractors met with representatives of the Department of Defense to discuss possible protocols for sharing information via computers. In , the U. Defence Department funded a project to develop a network, which can withstand the bombing.

Basically the idea was to develop a very secure network which can work even after a nuclear attack. The proposed network was not supposed to have a central control—which would be an obvious target. There were computers connected at about two dozen sites when the first email was sent in , but the number of sites and messages soon mushroomed. By there were 63 sites.

Protocol is a network term used to indicate the standard used by a network for communication. TCP "converts messages into streams of packets at the source, and they are reassembled back into messages at the destination. IP handles the dispatch of these packets. It handles the addressing, and makes sure that a packet reaches its destination through multiple nodes and even across multiple networks with multiple standards. The Internet has revolutionized the computer and communications world like nothing before.

The invention of the telegraph, telephone, radio, and computer set the stage for this unprecedented integration of capabilities. The Internet is at once a world-wide broadcasting capability, a mechanism for information dissemination, and a medium for collaboration and interaction between individuals and their computers without regard for geographic location.

The Internet represents one of the most successful examples of the benefits of sustained investment and commitment to research and development of information infrastructure. In the 's and 80's people who were online put out information about furniture and cars they wanted to sell. Debates raged about whether this was an appropriate use of the new research tool, the Internet, but when the Commercial Internet Exchange CIX was formed in the genie would not go back in the bottle.

As Tang and Teflon began as curiosities of the space program and later became common consumer products, so too have email, web research, and home shopping on the Web. It has only been ten years since the first relay between a commercial entity MCI Mail and the Internet was made. Since that time technologies have emerged that have fuelled the growth of private enterprise on the Web. In Paul Linder and Mark McCahill at the University of Minnesota released Gopher, a tool that allowed researchers to retrieve specific data from myriad 8 locations.

The Past, Present, and Future of the Internet As the technology advanced, the Internet became easier to use and the World Wide Web sites became more intricate and inviting. In shopping malls arrived on the Net. Of course, the advancements came with a downside. Vladimir Levin of Russia became the first publicly known Internet bank robber when he used the Internet to illegally transfer funds to his account saw the introduction of several emerging technologies such as JAVA and JAVAscript, Virtual Environments, and RealAudio which further enhanced the kind of product information which could be made available to consumers.

Commercial users now outnumbered research and academic users by a two to one margin, and Bill Gates decided to redefine Microsoft as an Internet company.

The Past, Present, and Future of the Internet Today one can shop online for books, food and wine, travel, and real estate. Other business activities include buying stocks and bonds, banking, and retirement planning.

In light of this growth, the U. Commerce Department will begin studying the impact of online shopping on total retail activity. Commerce Department to Measure Online Sales Consumer spending via the Internet draws much interest, but business to business activity is also booming. For further information on the history of the Internet, an extensive list of links may be found at the Internet Society Web site.

Connecting to the internet 1. May be four things, basically: mail, discussion groups, long- distance computing, and file transfers.

Internet mail is e-mail or electronic mail , 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. Programmers can maintain accounts on distant, powerful computers, execute programs. File transfers service allows Internet users to access remote machines and retrieve programs, data or text.

E-Mail Electronic Mail E-mail or Electronic mail is a 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.

It works 24 hours a day, seven days a week. You have the privilege of sending something extra even such as a file, graphics, images etc. 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.

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 email address provides all of the information required to get a message to the recipient from anywhere in the world.

Consider the e-mail ID john hotmail. Hotmail is the mail server where the mailbox "john" exists,. 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 "Client" is a program running on the your computer that enables you to talk to, and get stuff from, remote computers.

If one does not have an account in the remote FTP server, still he can connect to the server using anonymous login. Using anonymous login anyone can login in to a FTP server and can access public file archives, anywhere in the world, without having an account. One can easily Login to the FTP site with the username anonymous and e-mail address as password. 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 commands typed 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.

The WWW is a system that we use to access the Internet. One can easily surf the Web by jumping from one document to another using the links in those documents. These documents can be in many formats, such as text, graphics, animation, sound and latest is video. They may also be a combination of all these. All the information on Internet are presented to the user as a document or more popularly known as Web Page.

All these Web Pages are link to each other or even to section within a Web Page. And these links are known as Hyper Links. A Usenet newsgroup is a repository usually within the Usenet system, for messages posted from many users in different locations. Usenet newsgroups, are a similar e-mail conferencing system, but are less intrusive to the subscriber than list-servers since messages are posted to Usenet sites around the world instead of appearing in each subscriber's mailbox.

Usenet refers to the huge collection of messages which are posted to tens of thousands of newsgroups worldwide. Millions of people around the world regularly read newsgroup messages, following their favorite topics of interest. New newsgroups are added and old ones deleted every day. Usenet can provide a unique information resource not readily accessible from any other source. If you are looking for personal anecdotes about products, especially computer-related hardware and software products, how-to information, practical advice, or the latest news stories, newsgroup archives may be a valuable resource.

Typically, the newsgroup is focused on a particular topic of interest. Some newsgroups allow the posting of messages on a wide variety of themes, regarding anything a member chooses to discuss as on-topic, while others keep more strictly to their particular subject, frowning on off-topic postings. The news admin the administrator of a news server decides how long articles are kept on his server before being expired deleted. Different servers will have different retention times for the same newsgroup; some may keep articles for as little as one or two weeks, others may hold them for many months.

Some admins keep articles in local or technical newsgroups around longer than articles in other newsgroups. Newsgroups generally come in either of two types, binary or text. Hierarchies Newsgroups are often arranged into hierarchies, theoretically making it simpler to find related groups. The term top-level hierarchy refers to the hierarchy defined by the prefix before the first dot. The most commonly known hierarchies are the Usenet hierarchies.

So for instance newsgroup rec. One of the most popular ways is through the use of web or online conferencing. Videoconferencing is the conduct of a videoconference also known as a video conference or video teleconference by a set of telecommunication technologies which allow two or more locations to communicate by simultaneous two-way video and audio transmissions. It has also been called 'visual collaboration' and is a type of groupware. This can be as simple as a conversation between people in private offices point-to-point or involve several multipoint sites in large rooms at multiple locations.

Besides the audio and visual transmission of meeting activities, allied videoconferencing technologies can be used to share documents and display information on whiteboards. Web conferencing is currently being used by businesses for employee training, meetings and general communication. Educational institutions are using web conferencing as a way to enhance on-site classes or distance education classes.

Web conferencing is a tool which provides a way for "students" to share information, ask questions, get answers, discuss problems and work collaboratively. Conferencing provides opportunities to solve issues by providing a dynamic exchange of text, graphics, HTML links to information, audio, and video in a structured conversation organized by topic. Web conferences may take place in "real-time" where all participants are communicating at the same pre-arranged time. There are basically two kinds of videoconferencing systems: 1.

Dedicated systems have all required components packaged into a single piece of equipment, usually a console with a high quality remote controlled video camera. These cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom. They became known as PTZ cameras. The console contains all electrical interfaces, the control computer, and the software or hardware-based codec. There are several types of dedicated videoconferencing devices: 1.

Large group videoconferencing are non-portable, large, more expensive devices used for large rooms and auditoriums. Small group videoconferencing are non-portable or portable, smaller, less expensive devices used for small meeting rooms. Individual videoconferencing are usually portable devices, meant for single users, have fixed cameras, microphones and loudspeakers integrated into the console.

Desktop systems are add-ons hardware boards, usually to normal PCs, transforming them into videoconferencing devices. A range of different cameras and microphones can be used with the board, which contains the necessary codec and transmission interfaces. Videoconferences carried out via dispersed PCs are also known as e-meetings.

Internet Chat Communication on the Internet goes even further than personal e-mail, newsgroups and mailing lists, to encompass real-time conversations synchronous communication among two or more people. It consists of thousands of chat channels, each covering a different topic and with participants from all over the world.

Chat rooms The term chat room, or chatroom, is primarily used by mass media to describe any form of synchronous conferencing, occasionally even asynchronous conferencing.

The term can thus mean any technology ranging from real-time online chat over instant messaging and online forums to fully immersive graphical social environments. Text-based chat Online chat is a way of communicating by sending text messages to people in the same chat-room in real- time. Some chat rooms such as Yahoo! The oldest form of chat rooms are the text-based variety. These are characterized by using a graphic representation of the user [[Avatar virtualing elements such as games in particular massively multiplayer online games and educational material most often developed by individual site owners, who in general are simply more advanced users of the systems.

The most popular environments also allow users to create or build their own spaces. Some visual chat rooms also incorporate audio and video communications, so that users may actually see and hear each other. Chat room activities The primary use of a chat room is to share information via text with a group of other users. Generally speaking, the ability to converse with multiple people in the same conversation differentiates chat rooms from instant messaging programs, which are more typically designed for one-to-one communication.

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