In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication. Protocols may be implemented by hardware, software, or a combination of the two. At the lowest level, a protocol defines the behavior of a hardware connection. Image File history File links This is a lossless scalable vector image. ... Look up Protocol in Wiktionary, the free dictionary. ... Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... Communication is a process that allows beings - in particular humans - to exchange information by one of several methods. ... For other uses, see Data (disambiguation). ... For other uses, see Syntax (disambiguation). ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Typical properties

It is difficult to generalize about protocols because they vary so greatly in purpose and sophistication. Most protocols specify one or more of the following properties:

• Detection of the underlying physical connection (wired or wireless), or the existence of the other endpoint or node
• Handshaking
• Negotiation of various connection characteristics
• How to start and end a message
• How to format a message
• What to do with corrupted or improperly formatted messages (error correction)
• How to detect unexpected loss of the connection, and what to do next
• Termination of the session or connection.

In information technology, telecommunications, and related fields, handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins. ... It has been suggested that Error-correcting code be merged into this article or section. ...

Importance

The widespread use and expansion of communications protocols is both a prerequisite to the Internet, and a major contributor to its power and success. The pair of Internet Protocol (or IP) and Transmission Control Protocol (or TCP) are the most important of these, and the term TCP/IP refers to a collection (or protocol suite) of its most used protocols. Most of the Internet's communication protocols are described in the RFC documents of the Internet Engineering Task Force (or IETF). In the field of telecommunications, a communications protocol is the set of standard rules for data representation, signalling, authentication and error detection required to send information over a communications channel. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. ... It has been suggested that Internet Protocols be merged into this article or section. ... A protocol stack is a particular software implementation of a computer networking protocol suite. ... In internetworking and computer network engineering, Request for Comments (RFC) documents are a series of memoranda encompassing new research, innovations, and methodologies applicable to Internet technologies. ... The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ...

Object-oriented programming has extended the use of the term to include the programming protocols available for connections and communication between objects. Object-oriented programming (OOP) is a programming paradigm that uses objects to design applications and computer programs. ... In computer sciences object-oriented programming, a protocol (Java: interface) is what or how unrelated objects use to communicate with each other. ...

Generally, only the simplest protocols are used alone. Most protocols, especially in the context of communications or networking, are layered together into protocol stacks where the various tasks listed above are divided among different protocols in the stack. It has been suggested that this article or section be merged with communications protocol. ...

Whereas the protocol stack denotes a specific combination of protocols that work together, a reference model is a software architecture that lists each layer and the services each should offer. The classic seven-layer reference model is the OSI model, which is used for conceptualizing protocol stacks and peer entities. This reference model also provides an opportunity to teach more general software engineering concepts like hiding, modularity, and delegation of tasks. This model has endured in spite of the demise of many of its protocols (and protocol stacks) originally sanctioned by the ISO. The OSI model is not the only reference model however. Reference model, a notion used in standard conceptual (computing) models: OSI model - OSI Reference Models Open Geospatial Consortium - OGC Reference Models Von Neumann architecture - Sequential computing referencial model Federal Enterprise Architecture - Federal Enterprise Reference Models Many others This is a disambiguation page: a list of articles associated with the same... The software architecture of a program or computing system is the structure or structures of the system, which comprise software elements, the externally visible properties of those elements, and the relationships between them. ... The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design, developed as part of Open Systems Interconnection (OSI) initiative. ... Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. ... This article does not cite any references or sources. ...

Common Protocols

• IP (Internet Protocol)
• DHCP (Dynamic Host Configuration Protocol)
• TCP (Transmission Control Protocol)
• HTTP (Hypertext Transfer Protocol)
• FTP (File Transfer Protocol)
• Telnet (Telnet Remote Protocol)
• SSH (SSH Remote Protocol)
• POP3 (Post Office Protocol 3)
• SMTP (Simple Mail Transfer Protocol)
• IMAP (Internet Message Access Protocol)

The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... (DHCP) is a set of rules used by a communications device such as a computer, router or network adapter to allow the device to request and obtain an IP address from a server which has a list of addresses available for assignment. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on the World Wide Web. ... “FTP” redirects here. ... For the packet switched network, see Telenet. ... Secure Shell or SSH is a network protocol that allows data to be exchanged over a secure channel between two computers. ... In computing, local e-mail clients use the Post Office Protocol version 3 (POP3), an application-layer Internet standard protocol, to retrieve e-mail from a remote server over a TCP/IP connection. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... The Internet Message Access Protocol (commonly known as IMAP or IMAP4, and previously called Internet Mail Access Protocol, Interactive Mail Access Protocol (RFC 1064), and Interim Mail Access Protocol [1] ) is an application layer Internet protocol operating on port 143 that allows a local client to access e-mail on...

See also

• Internet protocol suite
• Communications protocol
• List of network protocols
• Application programming interface
• Calling convention