CoAP

The Constrained Application Protocol (CoAP) is an internet application protocol that has been designed to be very inexpensive, and as such, able to work on micro-controllers with very little RAM and code space. It is a powerful protocol to connect devices in the Internet of Things.

Just like HTTP, it implements the REST model, where servers make resources available, which then can be accessed via a URL using methods such as GET, PUT, POST and DELETE. This makes CoAP blend in very well with other HTTP sites, especially from a developer’s point of view. What makes it different from HTTP is the lightweight transport stack. It uses only few bytes for extra information in headers, and gets by with UDP on IP.