CODEWITHSUNDEEP
c#javascriptwindows-8backgroundmicrosoft-metro
Deeps
Deeps

Reputation: 567

How to use Time Trigger in background task in Windows 8 JS Metro App

I have a requirement where I have to call a service in background after every let say 1 hour to get some informations from server. I am working on JavaScript Metro Application. I have tried the background task and used Time Trigger and I have scheduled it to get triggered in every 15 minutes. It get called first time and then it is never called. I didn't close the background task because I want it to run all the time and call the service at scheduled time. I have used the Microsoft Background task sample for reference.

Please tell me what should be the best approach to call a service in background. How to use Time Trigger and Why Time Trigger doesn't get called after first time?

Please share code sample or walkthrough if any.

Thanks

Upvotes: 1

Views: 948

Answers (1)

harriha
harriha

Reputation: 301

First thing you should do is to close the background task properly as instructed in the documentation - if your tasks don't behave nicely, platform might suspend and refuse to run them for some time. You should let the platform handle triggering of the events based on the triggers and conditions you define instead of trying to bend the system. Also, remember that there's CPU and data usage quotas for background tasks present, one can't do massive amount of processing in background tasks - if the quotas are exceeded, tasks will get suspended. Be also sure that the background task works and doesn't throw errors.

In general, my recommendation is that one shouldn't rely solely on background tasks to fetch the information since it's not guaranteed that they manage to do it on time, so better to prepare for downloading the needed data in the foreground app as well. This obviously depends on the use case: if the data fetched in background tasks is not critical but more like nice-to-have, there's much less to worry about.

The TimeTrigger requires the app being added to the lock screen (see docs), but I guess you already meet this requirement since you've managed to get the task running once.

For debugging the background tasks, please take a look at Event Viewer, see detailed instructions. That page also contains some tips about common problems. The Event Viewer entry mentioned in that document is often a valuable resource for figuring out problems with the bg task execution. My guess is that you'll see errors there related to not closing the task properly.

Upvotes: 1

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