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title: Overview
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        <h1>CoAP</h1>
        <h2>RFC 7252 Constrained Application Protocol</h2>
        <p class='lead'>
          “The Constrained Application Protocol (CoAP) is a specialized web
          transfer protocol for use with constrained nodes and constrained
          networks in the
          <strong>Internet of Things.</strong>
          <br>
          The protocol is designed for machine-to-machine (M2M) applications
          such as smart energy and building automation.”
        </p>
      </div>
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        <div class='span4'>
          <h2>REST model for small devices</h2>
          <p>
            Like HTTP, CoAP is based on the wildly successful REST model:
            Servers make resources available under a URL, and clients access these resources using methods such as GET, PUT, POST, and DELETE.
          </p>
          <h3>Existing skills transfer</h3>
          <p>
            From a developer point of view, CoAP feels very much like HTTP.
            Obtaining a value from a sensor is not much different from obtaining a value from a Web API.
          </p>
          <h3>Ready for integration</h3>
          <p>
            Since HTTP and CoAP share the REST model, they can easily be connected using application-agnostic cross-protocol proxies.
            A Web client may not even notice that it just accessed a sensor resource!
          </p>
          <h3>Choose your data model</h3>
          <p>
            Like HTTP, CoAP can carry different types of payloads, and can identify which payload type is being used.  CoAP integrates with XML, JSON,
            <a href='http://cbor.io'>CBOR,</a>
            or any data format of your choice.
          </p>
        </div>
        <div class='span4'>
          <h2>Made for billions of nodes</h2>
          <p>
            The Internet of Things will need billions of nodes, many of which will need to be inexpensive.
            CoAP has been designed to work on microcontrollers with as low as 10 KiB of RAM and 100 KiB of code space (<a href='http://tools.ietf.org/html/rfc7228'>RFC 7228</a>).
          </p>
          <h3>Keep waste in check</h3>
          <p>
            CoAP is designed to use minimal resources, both on the device and on the network.
            Instead of a complex transport stack, it gets by with UDP on IP.
            A 4-byte fixed header and a compact encoding of options enables
            small messages that cause no or little fragmentation on the link
            layer.
            Many servers can operate in a completely stateless fashion.
          </p>
          <h3>Discovery integrated</h3>
          <p>
            The CoAP resource directory provides a way to discover the
            properties of the nodes on your network.
          </p>
        </div>
        <div class='span4'>
          <h2>Well-designed protocol</h2>
          <p>
            CoAP was developed as an Internet Standards Document,
            <a href='/spec.html'>RFC 7252.</a>
            The protocol has been designed to last for decades.
            Difficult issues such as congestion control have not been swept
            under the rug, but have been addressed using the state of the art.
          </p>
          <h3>Secure</h3>
          <p>
            The Internet of Things cannot spread as long as it can be exploited by hackers nilly-willy.
            CoAP does not just pay lip service to security, it actually provides strong security.
            CoAP's default choice of DTLS parameters is equivalent to
            3072-bit RSA keys, yet still runs fine on the smallest nodes.
          </p>
        </div>
      </div>