CoAP-Packet

CoAP-Packet is a generator and parser of CoAP packets for node.js.

What is CoAP?

Constrained Application Protocol (CoAP) is a software protocol intended to be used in very simple electronics devices that allows them to communicate interactively over the Internet. - Wikipedia

This library follows RFC 7252 and RFC 8974 for generating and parsing of CoAP packets. It also supports the method and option codes specified by other specifications, such as RFC 7641, RFC 7959, and RFC 8132.

It does not provide any CoAP semantics, it just parses the protocol.

CoAP-packet is an OPEN Open Source Project, see the Contributing section to find out what this means.

The library is being tested on Node versions 12, 14, and 16.

Installation

$: npm install coap-packet --save

Basic Example

The following example opens an UDP client and UDP server and sends a CoAP message between them:

const dgram = require('dgram')
const packet = require('coap-packet')
const parse = packet.parse
const generate = packet.generate
const payload = Buffer.from('Hello World')
const message = generate({ payload: payload })
const port = 41234
const client = dgram.createSocket('udp4')
const server = dgram.createSocket('udp4')

server.bind(port, function () {
  client.send(message, 0, message.length, 41234, 'localhost', function (err, bytes) {
    if (err) {
      console.error(err.message)
    }
    client.close()
  })
})

server.on('message', function (data) {
  console.log(parse(data).payload.toString())
  server.close()
})

API

• JS packet format
• coapPacket.parse()
• coapPacket.generate()

parse(buffer)

The parse function takes a buffer and returns a JS object that follows a particular format.

generate()

The generate function takes a JS object that follows a particular format and transform it into a CoAP packet.

JS packet format

The JS representation of a CoAP packet is:

{
  token: Buffer.alloc(4),
  code: '0.01',
  messageId: 42,
  payload: Buffer.alloc(200),
  options: [{
    name: 'If-Match',
    value: Buffer.alloc(5)
  }, {
    name: 'Uri-Path',
    value: Buffer.from('hello')
  }]
}

Instead of numerical codes, it also supports humanized names, e.g. GET, POST, PUT, DELETE.

Numerical codes can also be specified in HTTP format, like 500 or '404'.

Contributing

CoAP-Packet is an OPEN Open Source Project. This means that:

Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.

See the CONTRIBUTING.md file for more details.

Contributors

Coap-Packet is only possible due to the excellent work of the following contributors:

LICENSE

MIT, see LICENSE.md file.