https://twitter.com/oliyh/status/946791537781944321

I'm working on a ClojureScript app that needs to react to messages that it receives on an AWS SQS queue. What's the best practice for an endless receive loop in re-frame? I also need to handle user input, so it can't be blocking.

I think that you will use something like this @jmglov

(doto (new SQSConnection "")
  (.addHandler "on-messsage" (fn [m] (rf/dispatch [:new-sqs-message m]))))

Interesting. Is that using cljsjs/aws-sdk-js?

No. This is how I imagine the interface is

Ah... no, it's not like that.

I basically need to call (,receiveMessage sqs ...) in an endless loop.

There's no subscription with a handler.

I'm not sure where to put my endless loop and make it non-blocking.

It's a blocking call?

I'm sure core.async is my friend, but I'm not sure how and where to apply it.

The call itself is quick, so I don't mind if it blocks for a couple milliseconds.

But I need to poll for new messages once per second or so.

you can make it with timers*, every 10 seconds, call it and get new messages and dispatch to re-frame. *`js/setTimeout`

Yup, I'm going that route for now, with goog.Timer.

Seems yucky, but it should get the job done until I find a better way. 🙂

@jmglov do you have to turn this SQS polling "on" and "off" depending on application state? Or does it have to happen for the entire life of the application?

If the former, then you'll have to create an "effect" to do the turning "on" and "off". This FAQ may help: https://github.com/Day8/re-frame/blob/master/docs/FAQs/PollADatabaseEvery60.md (although you may well want a variation on this for your usecase) If the later, then your job is obviously simpler: just set up the timer when the app starts up, and leave it plugging away in the background, dispatching when something interesting happens.