Looking for design info, especially app life-cycle

I’m coming from the fitbit world where I have a published clock face that I want to port to run on a Galaxy Watch (just bought a watch 3). The clock face runs 24x7 and collects a trivial amount of data that is displayed on the face. The fitbit clock face was optimized to use very little power so the battery lasted for 5 days. I don’t expect for that long a battery life on the Galaxy Watch, but mention because I know how to minimize resource usage.

On the fitbit, clock faces exit if another app is run, or if the clock face is changed to a different face. So my clock face had to save info periodically to the file system and reload it on restart. And the user had to remember to restart the clock face after using anything else.

What is the life cycle like on the Galaxy Watch? Does a watch face continue running even if the user does other things (e…g makes a phone call, answers a text, runs an app, etc)? If so, can I split the watch face into a face and a background component of some sort that wold collect the data and pass it to the watch face when requested?

Is this documented anywhere? I saw descriptions of the some of the life cycle APIs, but could not find a good description of the overall environment.

Thanks for any pointers and help with terminology.


The best guide is to open a sample watchface from Tizen SDK. You can learn how it works on life example. Generally, in case watch face app the flow of the app is determined by events (event-driven programming) like tick every second etc

That is what I intend to try, but I know I’ll miss test cases that way.

Surely information about when the watch faces are started and stopped is documented somewhere? And how to communicate between a watch face and a service app?



In case Web API an app is started/loaded on onload() event and service_app_create() for native api respectively. You should study Tizen docs like this https://developer.tizen.org/development/training/native-application/understanding-tizen-programming
You will find there all you need to understand Tizen programming. Also programming hybrid apps you should find there (web app + native service). Native service works in case watch faces too if you ask about that.