Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Constrained Application Protocol
open-in-new
<p>Constrained Application Protocol (CoAP) is a specialized <a href="/facts/User_Datagram_Protocol/dxLU0D6q">UDP-based</a> Internet application protocol for constrained devices, as defined in <a href="https://datatracker.ietf.org/doc/html/rfc7252">RFC 7252</a> (published in 2014). It enables those constrained devices called "nodes" to communicate with the wider Internet using similar protocols. CoAP is designed for use between devices on the same constrained network (e.g., low-power, lossy networks), between devices and general nodes on the Internet, and between devices on different constrained networks both joined by an internet. CoAP is also being used via other mechanisms, such as SMS on mobile communication networks. </p><p>CoAP is an application-layer protocol that is intended for use in resource-constrained Internet devices, such as <a href="/facts/Wireless_sensor_network/r5LIAVsU">wireless sensor network</a> nodes. CoAP is designed to easily translate to <a href="/facts/HTTP/TWtvf7JD">HTTP</a> for simplified integration with the web, while also meeting specialized requirements such as <a href="/facts/Multicast/D9IspSfl">multicast</a> support, very low overhead, and simplicity. Multicast, low overhead, and simplicity are important for <a href="/facts/Internet_of_things/rwwGAxn3">Internet of things</a> (IoT) and <a href="/facts/Machine-to-machine/tdsbXlnr">machine-to-machine</a> (M2M) communication, which tend to be <a href="/facts/Embedded_system/a4muX1wU">embedded</a> and have much less memory and power supply than traditional Internet devices have. Therefore, efficiency is very important. CoAP can run on most devices that support UDP or a UDP analogue. </p><p>The Internet Engineering Task Force (<a href="/facts/IETF/tIcCsFhX">IETF</a>) Constrained <a href="/facts/RESTful/Q58zfr5h">RESTful</a> Environments Working Group (<a href="https://datatracker.ietf.org/doc/charter-ietf-core/">CoRE</a>) has done the major standardization work for this protocol. In order to make the protocol suitable to IoT and M2M applications, various new functions have been added. </p>