natsio/jetstream_pubsub.go

package natsio

import (
	"errors"
	"fmt"
	"github.com/nats-io/nats.go"
)

// Publish ...
func (js JetStream) Publish(subject string, payload []byte) error {
	_, err := js.instance.PublishAsync(subject, payload)
	if err != nil {
		msg := fmt.Sprintf("[natsio.JetStream] publish message to subject #%s error: %s", subject, err.Error())
		return errors.New(msg)
	}

	if js.debug {
		fmt.Printf("[natsio.JetStream] published a message to subject #%s \n", subject)
	}

	return nil
}

// Subscribe ...
func (js JetStream) Subscribe(subject string, cb nats.MsgHandler) (*nats.Subscription, error) {
	sub, err := js.instance.Subscribe(subject, cb)
	if err != nil {
		msg := fmt.Sprintf("[natsio.JetStream] subscribe subject %s error: %s", subject, err.Error())
		return nil, errors.New(msg)
	}

	if js.debug {
		fmt.Printf("[natsio.JetStream] subscribe new message from subject #%s \n", subject)
	}

	return sub, nil
}

func (js JetStream) PullSubscribe(subject, consumer string) (*nats.Subscription, error) {
	// check if consumer existed
	con, err := js.GetConsumerInfo(consumer)
	if con == nil || err != nil {
		msg := fmt.Sprintf("[natsio.JetStream] pull subscribe consumer %s not existed in stream %s", consumer, js.streamName)
		return nil, errors.New(msg)
	}

	// pull
	sub, err := js.instance.PullSubscribe(subject, consumer)
	if err != nil {
		msg := fmt.Sprintf("[natsio.JetStream] pull subscribe subject #%s - consumer #%s error: %s", subject, consumer, err.Error())
		return nil, errors.New(msg)
	}

	if js.debug {
		fmt.Printf("[natsio.JetStream] pull subscribe new message from subject #%s \n", subject)
	}

	return sub, nil
}