What is CoAP?
CoAP or Constrained Application Protocol, as the name suggests, is an application layer protocol that was introduced by the Internet Engineering Task Force in the year 2014. CoAP is basically designed for the constrained environment.
It is a web-based protocol that resembles HTTP. It is also based on the request-response model. Based on the REST-style architecture, this protocol considers the various objects in the network as resources. These resources are uniquely assigned a URI or Uniform Resource Identifier. The data from one resource to another resource is transferred in the form of CoAP message packets whose format is briefly described later.
The Client requests for some resources and in response to that, the server sends some response over which the client sends an acknowledgement. Although, some types of CoAP do not involve the receiver sending acknowledgments for the information received. This type of CoAP message is called NoN or Non Confirmable messages, whereas the messages in which the receiver sends a response to sender is known as CON or confirmable messages.
Similar to HTTP, a CoAP request is sent by a client using a method code to request an action on a URI identifiable object.
The server replies with a response code which may include a resource representation. CoAP model is essentially a client/server model enabling the client to request for service from server as needed and the server responds to client’s request.
However, CoAP messages are asynchronous since it uses UDP. The message layer interfaces with UDP layer which formats the data received into a datagram and sends it to the lower layer of the OSI or the TCP/IP model.
Constrained Application Protocol (CoAP)
There are several protocols in the application layer of the Internet protocol suite. One such useful protocol is the CoAP or Constrained Application Protocol. This protocol has a wide range of advantages and applications in the field of the Internet of Things (IoT) and cloud computing. CoAP also has a powerful contribution in providing versatile solutions to IoT applications.
This article delves into a set of key topics and fundamental concepts in CoAP protocol along with its applications in the real world.