@sirena-lwm2m/coap

RFC 7252 CoAP stack for Node.js with RFC 8323 TCP transport support.

Installation

npm install @sirena-lwm2m/coap

Quick start — UDP

import { createServer, Response, stringToBytes } from '@sirena-lwm2m/coap';

const server = createServer({
  listen: [{ host: '0.0.0.0', port: 5683 }],
});

server.on('request', async (req, ctx) => {
  await ctx.respond(Response.ok(stringToBytes(req.url)));
});

await server.start();
console.log('Listening on:', server.listenerSummary());

TCP transport (RFC 8323)

The server supports CoAP over TCP using the coap+tcp:// URI scheme. Bind one or more TCP listeners alongside UDP by passing URI strings to the listen array.

import { createServer, Response, stringToBytes } from '@sirena-lwm2m/coap';

const server = createServer({
  listen: [
    'coap://127.0.0.1:5683',     // UDP
    'coap+tcp://127.0.0.1:5684', // TCP (RFC 8323)
  ],
});

server.on('request', async (req, ctx) => {
  // ctx.transport is 'udp' or 'tcp'
  console.log(`[${ctx.transport}] ${req.url}`);
  await ctx.respond(Response.ok(stringToBytes(`hello via ${ctx.transport}`)));
});

await server.start();
console.log('Listening on:', server.listenerSummary());
await server.stop();

See examples/slice-2.ts for a working dual-transport demo.

See docs/tcp-transport.md for framing details, connection multiplexing, and configuration.

ExchangeContext

Every 'request' event handler receives a Request and an ExchangeContext:

interface ExchangeContext {
  remote: string;           // "ip:port" of the sender
  local: string;            // "ip:port" of the receiving socket
  transport: 'udp' | 'tcp'; // which transport delivered this request
  token: Uint8Array;        // CoAP token bytes
  messageId: number;        // CoAP message ID (0 for TCP)
  options: CoapOption[];    // raw parsed options
  peer: Peer;               // { mode: 'anonymous' }
  respond(res: Response): Promise<void>;
  cancel(): void;
  abort(code: CoapCode): void;
}

License

MIT