This Ruby gem implements client functionality for RFC 7252, the Constrained Application Protocol (CoAP). The message parsing code included is written by Carsten Bormann, one of the RFC authors.

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained (e.g., low-power, lossy) networks. The nodes often have 8-bit microcontrollers with small amounts of ROM and RAM, while constrained networks such as 6LoWPAN often have high packet error rates and a typical throughput of 10s of kbit/s. The protocol is designed for machine-to-machine (M2M) applications such as smart energy and building automation.

Additionally supported extensions of the CoAP protocol:

• Blockwise Transfer
• Observe

Add this line to your application's Gemfile:

gem 'coap'

And then execute:

$ bundle

Or install it yourself as:

$ gem install coap

require 'coap'

CoAP::Client.new.get_by_uri('coap://coap.me/hello').payload
=> "world"

CoAP::Client.new.get('/hello', 'coap.me')
=> #<struct CoRE::CoAP::Message ver=1, tt=:ack, mcode=[2, 5], mid=51490, options={:max_age=>60, :token=>366862489, :content_format=>0}, payload="world">

c = CoAP::Client.new(host: 'coap.me')
c.get('/hello')

See the API documentation at rubydoc.info or test/test_client.rb for more examples.

The command line client supports the basic CoAP methods.

coap get coap://coap.me/.well-known/core

You can skip the install section if you want to use Docker.

docker run nning2/coap get coap://coap.me/hello

rake

The code is published under the MIT license (see the LICENSE file).

• Carsten Bormann
• Simon Frerichs
• henning mueller