Module @pamoja/coap

Ergonomic facade over the generated CoAP binding.

CoAP is the transport for links where MQTT is more than the budget allows: it runs over UDP, its headers are a handful of bytes, and a node can fire a reading and forget it rather than holding a session open.

The reliability choice is re-exported as a runtime Reliability object, because the generated enum is types-only.

@pamoja/coap

A CoAP client over UDP with confirmable delivery and observe. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

npm install @pamoja/coap

This pulls in @pamoja/native, the compiled engine. npm install pamoja is the whole framework in one package.

Example

The test that runs in CI, spliced here as it ran.

From bindings/node/guides/coap.ts:

import { CoapClient, Reliability } from '@pamoja/coap'

async function main(): Promise<void> {
  // CoAP runs over UDP and opens no session, so connecting only binds a local socket.
  // Nothing is listening on the far side here, and for a non-confirmable send nothing
  // needs to be.
  const reporter = new CoapClient({
    host: '127.0.0.1',
    port: 5683,
    reliability: Reliability.NonConfirmable,
  })
  await reporter.connect()
  console.log(`reporter  connected: ${await reporter.isConnected()}`)

  // Non-confirmable delivery is at most once: the datagram leaves unacknowledged, which is
  // what a battery-powered node sends when one missed reading costs nothing.
  await reporter.send('sensors/1/temperature', Buffer.from('21.5'))
  console.log('reporter  sent 21.5 and did not wait for an answer')

  // A command is different: it has to arrive. Confirmable delivery retransmits until an
  // acknowledgement comes back. RFC 7252 fixes the defaults at a two-second wait and four
  // retransmissions; both are cut short here so the guide does not sit waiting.
  const commander = new CoapClient({
    host: '127.0.0.1',
    port: 5683,
    reliability: Reliability.Confirmable,
    ackTimeoutMs: 20,
    maxRetransmits: 1,
  })
  await commander.connect()
  try {
    await commander.send('actuators/valve', Buffer.from('open'))
    console.log('commander the valve acknowledged the command')
  } catch (error) {
    console.log(`commander gave up unacknowledged: ${(error as Error).message}`)
  }

  await reporter.disconnect()
  console.log(`reporter  disconnected: ${!(await reporter.isConnected())}`)
}

main()

The same capability in every language

Language	Package	Reference
Rust	`pamoja-coap`	reference, docs.rs, install
TypeScript	`@pamoja/coap`	reference, install
Python	`pamoja-coap`	reference, install
C#	`Pamoja.Coap`	reference, install