monero-lws/docs/zmq.md

monero-lws ZeroMQ Usage

Monero-lws uses ZeroMQ-RPC to retrieve information from a Monero daemon, ZeroMQ-SUB to get immediate notifications of blocks and transactions from a Monero daemon, and ZeroMQ-PUB to notify external applications of payment_id (web)hooks.

External "pub" socket

The bind location of the ZMQ-PUB socket is specified with the --zmq-pub option. Users are still required to "subscribe" to topics:

• json-full-pyment_hook: A JSON array of webhook payment events that have recently triggered (identical output as webhook).
• msgpack-full-payment_hook: A msgpack array of webhook payment events that have recently triggered (identical output as webhook).

json-full-payment_hook/msgpack-full-payment_hook

These topics receive PUB messages when a webhook (webhook_add), event is triggered. If the specified URL is zmq, then notifications are only done over the ZMQ-PUB socket, otherwise the notification is sent over ZMQ-PUB socket AND the specified URL. Invoking webhook_add with a payment_id of zeroes (the field is optional in webhook_add), will match on all transactions that lack a payment_id`.

Example of the "raw" output from ZMQ-SUB side:

json-full-payment_hook:{
  "index": 2,
  "event": {
    "event": "tx-confirmation",
    "payment_id": "4f695d197f2a3c54",
    "token": "single zmq wallet",
    "confirmations": 1,
    "event_id": "3894f98f5dd54af5857e4f8a961a4e57",
    "tx_info": {
      "id": {
        "high": 0,
        "low": 5666768
      },
      "block": 2265961,
      "index": 1,
      "amount": 3117324236131,
      "timestamp": 1687301600,
      "tx_hash": "ef3187775584351cc5109de124b877bcc530fb3fdbf77895329dd447902cc566",
      "tx_prefix_hash": "064884b8a8f903edcfebab830707ed44b633438b47c95a83320f4438b1b28626",
      "tx_public": "54dce1a6eebafa2fdedcea5e373ef9de1c3d2737ae9f809e80958d1ba4590d74",
      "rct_mask": "4cdc4c4e340aacb4741ba20f9b0b859242ecdad2fcc251f71d81123a47db3400",
      "payment_id": "4f695d197f2a3c54",
      "unlock_time": 0,
      "mixin_count": 15,
      "coinbase": false
    }
  }
}

Notice the json-full-payment_hook: prefix - this is required for the ZMQ PUB/SUB subscription model. The subscriber requests data from a certain "topic" where matching is done by string prefixes.

index is a counter used to detect dropped messages.

The block and id fields in the above example are NOT present when confirmations == 0.