kats

Simple and durable subscription system for Krist using NATS.

Installation

The recommended installation method for kats is using Docker. Example nats-server.conf and docker-compose.yml files are provided to get you started.

git clone [email protected]:Lustyn/kats.git
cd kats
docker compose up -d

Alternatively, the Dockerfile and images available at ghcr.io/lustyn/kats can be used to run the container in any OCI-compliant runtime, like containerd in Kubernetes.

Usage

All Krist transactions are reconciled (since the start of the chain) and stored into a JetStream called krist. Subjects are formatted as krist.from.<address>.to.<address> and messages are the transaction object. Subjects can be used to filter to listen for events from a particular address, and consumers can opt to use different a DeliveryPolicy if they want to process all messages since the start of Krist or only new messages.

For example, in the JavaScript NATS client you can do the following:

const nc = nats.connect({
  servers: process.env.NATS_SERVER ?? "127.0.0.1",
  user: process.env.NATS_USER ?? "krist",
  pass: process.env.NATS_PASSWORD ?? "krist",
});

const jsm = nc.jetstreamManager();

await jsm.consumers.add("krist", {
  durable_name: "my-krist-consumer",
  deliver_policy: DeliverPolicy.New,
  ack_policy: AckPolicy.Explicit,
  replay_policy: ReplayPolicy.Instant,
  filter_subject: `krist.from.*.to.${process.env.KRIST_ADDRESS}`,
});

const kristConsumer = await js.consumers.get("krist", "my-krist-consumer");

const transactionMsgs = await kristConsumer.consume();
for await (const msg of transactionMsgs) {
  const transaction = msg.json<KristTransaction>();
  console.log("Processing transaction", transaction);
  msg.ack();
}