Prologue

Abstract

Digital communication has developed into one of the driving technical and cultural forces in the 21st century. More than ever has it become impossible to imagine living in today’s world without the Internet as our universal communication medium. In the first volume of this series the focus was on the general foundation of digital communication, i.e., the basics of computer networking, media encoding technology and digital security. In this volume, the Internet, with its various contributors, technological foundation and numerous protocols and technologies, will be covered.

“Read quickly, because nothing is more certain than change on the Internet!”

– Anita Berres (German journalist)

Glossary

Advanced Research Projects Agency Net (ARPANET)

The first packet switching data network and forerunner of the Internet. It was founded by the DARPA, a research initiative of the US Department of Defense. The first network node (Interface Message Processor, IMP) was ready for employment on August 30, 1969 and the ARPANET began operation in December 1969 with 4 IMPs in Stanford, Santa Barbara, Los Angeles and Utah. It was comprised of multiple satellites at its highpoint, among them were those from the West to the East Coast of the USA to Hawaii, Great Britain, Norway, Korea and Germany. The ARPANET ended its operation in July 1990

Client

This designates a program that contacts a server from which it requests information services. The browser used in WWW is in this sense a client. There are also other clients in WWW that contact the WWW server in order to download information e.g. search engines or agents

Client/server architecture

An application is carried out based on a network of multiple computers connected to each other. The server provides specific services, the client, on the other hand requests services. Except for allocation and answering in connection with the task at hand, the components are independent of each other. Interface and the type of communication necessary for order submissions and responses are clearly defined

Communication

Communication can be understood as the process of individually or mutually supplying, transmitting, and processing information by people or technical systems

Communication protocol

A communication protocol (or simply protocol) is a collection of rules and requirements that define the data format of information to be transmitted as well as the way of transmission. They contain agreements about the data packets to be sent, the establishment and termination of the connection between the communication partners as well as how the data is to be sent

Digital communication

Digital communication is a term used to describe the exchange of digital information over specialized, digital communication channels intended for this purpose. The type of media (text, image, audio, video, etc.) determines the data format of the information. The information is transmitted according to the requirements of the implemented communication protocols over the communication channel (e.g., Internet or WWW)

Dot-com bubble

The expression dot-com-bubble was a word originating in the media that came to be used for a worldwide phenomenon. It primarily gained use in connection with the collapse of stock market speculation in March 2000—when “the bubble burst.” The so-called dot-com companies were particularly affected by this turn of events. Particularly in industrial countries it led to major losses for small investors. Dot-com companies are characteristically technological companies whose field of business involves Internet services. The name comes from the “.com” ending of the domain names of these companies. It was first coined in the jargon of the stock exchange and then adopted in the media

Electronic commerce (also e-commerce)

Electronic commerce describes that part of electronic business involving Internet-based agreements and legally-binding business transactions. E-commerce normally encompasses the three transaction phases: information, agreement, transaction

HTML

Hypertext Markup Language the standardized document format for hypermedia documents in WWW. Documents that can be transmitted and represented by the browser in the WWW by means of HTTP are encoded in HTML

HTTP

Hypertext Transfer Protocol the protocol regulating the WWW communication of browsers and WWW servers. If a browsers requests a document from the WWW server or answers a request from the WWW server this communication must obey the conventions of the HTTP protocol

Hyperlink

Reference to another hypermedia document or text passage in the same hypertext. This enables a (non-linear) linking of information in different documents

Internet

The Internet is the largest computer network in the world. It made up of many networks connected to each other as well as individual resources. Among the most important services of the Internet are: electronic mail (email), hyper-media documents (WWW), file transfer (FTP) and discussion forums (Usenet/Newsgroups). The global network gained its popularity primarily through the introduction of the World Wide Web (WWW). While this is often spoken of as synonymous with the Internet, it is in fact just a subset and represents one of the many Internet services

Internetworking

A technique for bridging multiple different and possibly incompatible networks (LANs, WANs) into one Internet. To enable this, suitable switching computers (routers) are necessary, which mediate the path of a data packet through the network and ensure a secure delivery. The network appears as a homogeneous, virtual network (Internet) to the user

Internet standard

Because many companies and organizations were involved in the development of the Internet it was necessary to create standardized protocols and interfaces to simplify the development effort. These were adopted in the form of Internet standards in a public standardization process. It thus became possible for every user to take a position on a new proposal for a future standard (Request for Comment RFC) and thereby play a role in steering the course of Internet development

Internet Protocol (IP)

Protocol on the network layer of the TCP/IP reference model, more precisely called IPv4. As one of the pillars of the Internet, IP ensures that the global Internet, consisting of many heterogeneous, individual networks appears as a unified homogeneous network. A standardized addressing scheme (IP addresses) enables worldwide unambiguous computer identification. IP additionally provides a connectionless, packet switching datagram service that cannot fulfill quality of service guarantees, but always works according to the best effort principle. For the communication of control information and error notification, the ICMP protocol is an integral component of the IP

Medium

The expression of a transportation channel for information transmission between a sender and a receiver. In order to transport information it must be be exchanged over a carrier medium set up between the sender and receiver

Multimedia

A multimedia information presentation is referred to when the information presented involves multiple and varied media, for example, text, image, and sound

Network application

An application program whose operation includes access to resources that are not locally available from the executing computer but attainable at a remote computer that then must be accessible over a network

Request for Comments (RFC)

New technologies in the Internet developing from expert discussions are recorded in so-called RFCs. In the course of the Internet standardization processes a consecutively and chronologically numbered collection of documents was begun, in which technologies, standards and further Internet-related information have been documented and standardized

Semantic Web

The semantic web represents an expansion of the existing World Wide Web. Every information content represented in the semantic web is given a well-defined and machine-readable meaning. This should enable a program, acting autonomously, to interpret the information and to be capable of making decisions based on it. The concept of the semantic web originated in a proposal by the WWW founder Tim Berners-Lee

Server

Designates a process which is contacted by clients in order to send back requested information or to make resources available. A computer on which a server process is carried out is often referred to as a server

TCP/IP reference model (also TCP/IP protocol suite

TCP/IP communication model), This term refers to the communication layer model for the Internet. The TCP/IP reference model is divided into 4 protocol layers. These are: the data link layer, the Internet layer, the transport layer, and the application layer. In this way it is possible for different computers and protocol worlds to be able to communicate over unified interfaces on the Internet

Uniform Resource Identifier (URI)

Serves as the world-wide unique identification of information resources in the WWW. Implemented as Uniform Resource Locator (URL) at this time in the form of a unique address. As the address of an information resource in WWW is subject to change, work is being done on the creation of a Uniform Resource Name (URN) that identifies an information resource explicitly by its name and not by its address

Web 2.0

Web 2.0 identifies a seemingly new generation of web-based services that are characterized by the simple possibility they also offer to lay people to participate and interact in the WWW. Typical examples of these services are wikis, weblogs, image and video portals, or peer-to-peer exchanges

World Wide Web

Term for the “worldwide data net” (also WWW, 3 W, W3, Web). The most successful service on the Internet distinguishes itself by its high degree of userfriendliness as well as its multimedia elements. WWW in fact designates a technology that implements a distributed, Internet-based hypermedia document model. Internet and the World Wide Web (WWW) are often used as synonyms today, however the WWW is only a special service in the Internet using the HTTP protocol