The increasing importance of fast and reliable communication has resulted in the creation of certain communication rules, which nowadays, we call communication protocols. In this chapter, a historical overview of early protocol development and deployment is presented as a look-back to the evolution of communication protocols. Then we introduce the most important terms and notions of the protocol theory. To make it easier to understand these concepts, we use the INRES protocol as demonstration tool. In the next topic, we summarize the steps of the protocol engineering. At the end of the chapter, we give some guidelines for protocol classification.
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This chapter provides an introduction into the world of protocols: the communication rules which are responsible for controlling various communication services. Communication rules are presented by introducing syntax (what sort of notation is used, what are the names of the messages, how the messages are structured, what are the components of the messages), semantics (what kind of messages are sent and expected as response in certain situations), and temporal rules (a strict and limited timing aspect, the encoded lifetime of every message sent). The author also presents various protocol classification methods, based on different points of view.
If we want to exactly determine the behavior of a living or a lifeless system, the interactions have to be in the center of our examinations, because actions and reactions follow each other. The communication protocols specify the rules and laws describing the interactions of computer, telecommunication, industrial etc. networks. It is very important to note that the protocols in this chapter always refer to communication protocols.
The notion of protocol was simultaneously used in 1967 in two networks, in the Advanced Research Projects Agency Network (ARPANET) and in the National Physical Laboratory Network (NPL-NET). NPL-NET was designed to elaborate physical data transmission and evaluation, and it was operating in Daresbury, United Kingdom. ARPANET, which came into general use in the United States, was created to handle communications among computer users. Both systems implemented a revolutionary method for data communication called packet switching, the transmission of data streams, which were composed of messages with unified lengths. Using the packet switching method, the size of the data packages could be set to require only an average store capacity in the node. Then the packet could be forwarded so it would not occupy the whole dedicated route but only a path between two nodes following each other. After various modifications and fine-tuning of the network itself, the descendant of ARPANET first mentioned as Internet in 1974, became used worldwide. Communication via the Internet is realized by a set of protocols called the Internet Protocol Suite also known as the Transmission Control Protocol/Internet Protocol (TCP/IP) stack, specified by the Internet Engineering Task Force (IETF).
The NPL protocols referred to the reference model of the Open System Interconnection (OSI) determined by the International Organization for Standardization (ISO). Based on the experience of working with the NPL protocols, the European Organization Conseil Européenne pour la Recherche Nucléaire (CERN) developed the World Wide Web (WWW) in 1992. The basic protocol component of the Web is the Hypertext Transfer Protocol (HTTP) providing excellent searching and browsing possibilities (Buchanan, 1999; Davies et. al. 1982).
The main reason why the use of computer networks and communication protocols became widespread is the coexistence of the Internet and the Web. Nowadays the Internet and the Web are used together.
The importance of protocols is considerably growing because of the so-called information boom. This concept concerns both the personal communication and the industrial processes. The computers and computer networks play an important role in our everyday life and they are also important in several areas, such as online libraries and dictionaries, mass production, computer-aided planning, e-business and e-learning, web trading, the stock exchange, advertisements, sensor networks, the GPS, and even the CERN fusion reactor.
In this chapter, an introductory overview is given about the basic syntactic, semantic, and temporal rules of protocol operation.
This chapter consists of four subchapters. After the introduction, the first subchapter contains a historical overview of communication protocols. First the optical semaphore system developed in the Napoleonic times is presented, then it is illustrated how the evolution of Internet and NPL protocols took place starting from basic physical measurements and gradually developing into very complex communication systems.
The second subchapter discusses the syntactic, semantic, and temporal rules of operation and specifies the qualitative and quantitative protocol parameters and features. The INRES protocol is used to illustrate the protocol operation.