threedotslabs / watermill-jetstream Goto Github PK

I'm working on another integration where I want to be able to use core NATS for certain sets of publishers to try and improve throughput. Something I noticed is that you can pretty trivially form an interface for the methods we need (note the removal of options from the signatures):

type Connection interface {
	Subscribe(string, nats.MsgHandler) (*nats.Subscription, error)
	PublishMsg(*nats.Msg) error
	Drain() error
}

*nats.Conn already implements this, which gives you core NATS support. You can then trivially bind over this for jetstream:

// connection mimics the core NATS publish/subscribe API
// so that NATS and jetstream can use the same client orchestration.
type connection struct {
	conn   *nats.Conn
	js     nats.JetStream
}

func (j connection) Subscribe(s string, handler nats.MsgHandler) (*nats.Subscription, error) {
	subOpts := make([]nats.SubOpt, 0)

	//TODO: populate options from config

	return j.js.Subscribe(s, handler, subOpts...)
}

func (j connection) PublishMsg(msg *nats.Msg) (err error) {
	pubOpts := make([]nats.PubOpt, 0)

	//TODO: populate options from config

	_, err = j.js.PublishMsg(msg, pubOpts...)

	return
}

func (j connection) Drain() error {
	return j.conn.Drain()
}

I am not sure how valuable this would be in watermill, but I think it would be pretty easy. Most of the work would likely be to define the new core NATS configurations and setup appropriate tests.

What is the reason behind altering the publisher's subject naming during marshaling? This makes subscribing to the same subject very complicated. I had to remove this modification in my code to be able to publish and subscribe to the same topic successfully.

Changing it would be a breaking change, but there would be a way to just release the change as a feature without breaking changes. However, the reason behind having it is still unknown to me. If you agree to the change and still keep this behavior, for now, I'd be happy to create a PR.

Maybe we could provide in a _example directory in this repo for simplicity but thinking about this one:

https://github.com/ThreeDotsLabs/nats-example

I think some documentation for users for getting started easier would be nice.

I'd like to offer to extend the README and the docs on the website accordingly.