Real-time communication (RTC) is a category of software protocols and communication hardware media that gives real-time guarantees, which is necessary to support real-time guarantees of

real-time computing Real-time computing (RTC) is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constrai ...

.Sharad Sundaresan; Riccardo Bettati
"Distributed Connection Management for Real-Time Communication over Wormhole-Routed Networks"
1997. Real-time communication

protocols Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

are dependent not only on the validity and integrity of data transferred but also the timeliness of the transfer. Real-time communication systems are generally understood as one of two types: ''Hard Real-Time (HRT)'' and ''Soft Real-Time (SRT)''. The difference between a hard and soft real-time communication system is the consequences of incorrect operation. Safety-critical systems capable of causing catastrophic consequences upon a fault, such as aircraft fly-by-wire systems, are designated as hard real-time, whereas non-critical but ideally real-time systems, such as hotel reservation systems, are designated as soft real-time. The designation of a real-time communication system as hard or soft has significant influence on its design.

Hard Real-Time Systems

Hard real-time communication systems are frequently electromechanically linked to a physical mechanism, often one that interfaces directly with people or property, which often contributes to or defines the potential danger of a fault. Due to their safety-critical nature, the communication protocols defined in a hard real-time system generally must be

deterministic Determinism is a philosophical view, where all events are determined completely by previously existing causes. Deterministic theories throughout the history of philosophy have developed from diverse and sometimes overlapping motives and consi ...

. Hard real-time communication systems are particularly common in the

transportation Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, ...

industrial Industrial may refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems * Industrial city, a city dominate ...

, and

medical Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practic ...

sectors. Common applications include

control systems A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large industrial c ...

, automotive controllers,

medical devices A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

, and critical safety systems such as airbag firing computers.

Examples

* The

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...

communication network A telecommunications network is a group of nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, messag ...

SpaceWire SpaceWire is a spacecraft communication network based in part on the IEEE 1355 standard of communications. It is coordinated by the European Space Agency (ESA) in collaboration with international space agencies including NASA, JAXA, and RKA. ...

supports real-time communication. * Time-Triggered Ethernet supports real-time synchronous communication in complex multi-hop Ethernet networks.

Soft Real-Time Systems

Unlike hard real-time communication systems, soft real-time communication systems generally do not have the capacity to cause catastrophic harm upon a fault, which allows for non-deterministic, less rigorous

network infrastructure A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...

. This allows soft real-time communication systems to operate over consumer networks such as residential internet connections and

cellular networks A cellular network or mobile network is a communication network where the link to and from end nodes is wireless. The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver (typically thre ...

. A large amount of soft real-time systems are

telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

products such as VOIP systems and certain

video calling Videotelephony, also known as videoconferencing and video teleconferencing, is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication.McGraw-Hill Concise Ency ...

platforms such as

Discord Discord is a VoIP and instant messaging social platform. Users have the ability to communicate with voice calls, video calls, text messaging, media and files in private chats or as part of communities called "servers".The developer documenta ...

and

Google Meet Google Meet (formerly known as Hangouts Meet) is a video-communication service developed by Google. It is one of two apps that constitute the replacement for Google Hangouts, the other being Google Chat. It replaced the consumer-facing Google ...

. Data transmitted over a soft real-time communication system is not stored in a centralized server, and peers are connected directly to one another rather than through a server, although intermediary connecting nodes between peers are allowed when a direct link cannot be established.

Examples

WebRTC WebRTC (Web Real-Time Communication) is a free and open-source project providing web browsers and mobile applications with real-time communication (RTC) via application programming interfaces (APIs). It allows audio and video communication to wor ...

, an

open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

real-time communication

framework A framework is a generic term commonly referring to an essential supporting structure which other things are built on top of. Framework may refer to: Computing * Application framework, used to implement the structure of an application for an op ...

for mobile applications and web browsers, is the current most prominent implementation of real-time communication in the web-oriented telecommunications space.

References

{{reflist Communication software Voice over IP Multimedia