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constrained application protocol (CoAP)

Constrained Application Protocol (CoAP) is a web transfer protocol developed by the Internet Engineering Task Force ( IETF) for the Internet of Things( IoT) or for M2M communication. It is based on Representational State Transfer( REST), the architectural model for web services, where resources are controlled by servers through an application process and identified via Uniform Resource Identifiers( URI).

The CoAP protocol is a pure binary protocol and cannot be represented in the ASCII character set. It was designed for simple applications and is organized over two layers: The Transport Layer and the Transaction Layer. A major difference between HTTP and CoAP is the transport layer on which both protocols are built. While the HTTP protocol uses the Transmission Control Protocol( TCP), which is relatively unsuitable for Low Power and Lossy Networks( LLN) because the overhead is too large for deterministic transactions, the CoAP protocol works with the User Datagram Protocol( UDP), which has a much smaller overhead.

Embedding the CoAP protocol with UDP and 6LoWPAN

Embedding the CoAP protocol with UDP and 6LoWPAN

The Transaction Layer is used to exchange messages between endpoints. A distinction is made between four message types: confirmables, which are messages to be confirmed, non-confirmables, which are messages not to be confirmed, acknowledgement, which is the confirmation of a message to be confirmed, and reset indicates that a confirmable message was received but cannot be processed further.

The CoAP protocol is also used as an application protocol in Lightweight M2M( LWM2M), in Lemonbeat and in IoTivity, among others.

Informations:
Englisch: constrained application protocol - CoAP
Updated at: 06.07.2016
#Words: 246
Links: protocol, Internet, Internet engineering task force (IETF), Internet of things (IoT), market to market (M2M)
Translations: DE
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