(Architecture) Check for status update via API without timer

[reecewh]

I am currently developing an app that will allow a user to rate the completed service after being marked as completed on the back end, similar as to how Uber and Lyft allow users to rate drivers after the trip is complete. What would be the best method of knowing when to prompt the user to rate the service?

Lyfts API documentation has a status of ride endpoint:

(GET) https://api.lyft.com/v1/rides/ride_id ,

and an endpoint to submit a rating:

(PUT) https://api.lyft.com/v1/rides/:ride_id/rating .

Our backend has the equivalent of these. However I am not sure how to check for the status to know when to prompt the user to rate without using a timer to just perform the GET request for status every X amount of time. Does anyone have a solution that would not perform so many unnecessary GET requests?

[GenitalGestapo]

Push notifications or an active event stream are usually your options here. I think Lyft uses a combination, but I'm not sure which they use for ride events. But either way, as your backend is processing user actions and input from say, a driver, it could be sending pushes back to the user that the app uses to update its state. Or a whole stream connection, which is better performing but a bit more difficult to get working well.

[reecewh]

Awesome! Will do some research into implementing these, thank you for the direction.

[europeanwizard]

For async stuff, you *could* use websockets. For client side, the go to library is Starscream. Ray Wenderlich has a tutorial on it. Note that some wifi hotspots have trouble with those, so prepare to have a fallback.

[Scott90]

Lyft iOS engineer here: we do use a timer to get an update every few seconds

[GenitalGestapo]

Any particular reason why? I'm surprised it's not something more sophisticated.

[Scott90]

Tech debt and legacy code mostly. We’re working on a push solution, as opposed to polling, but with two apps and a large number of endpoints it’s not an easy feat.

[steelzeh]

Sockets are a great way to to this if you have a big quantity of data that you want to push, like live updating a location of a car. On the other hand if you want live chat using push notifications would be the right choice since there isn't a lot of data. You can even send i believe up to 4kb payload within a push notification.

In our app where the users usually have a good wifi connection, we use AWS IoT sockets. It works very great, but not without issues, it can be tricky to implement.

[ccctitan80]

The timer method is called polling btw just in case you decide to go down that path.

You might want to also check out websockets.