Is there an easy way to datadog monitors to hold alerts to allow time for the cloud to self resolve?
My team often gets alerted for monitors that self resolve before we have a chance to address it. If datadog could hold the alert for 5-10 minutes we would avoid unactionable alerts.
Change the alert window to be longer.
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The app I worked on got an alert from apple wallet: "Some passes are receiving too many updates, which may affect battery life. Automatic updates for *** passes will be disabled. Choose RE-enable if you want automatic updates to continue." I only have 2 passes in the wallet from that app.
Does anyone know what's the reason trigger this alert? If we send 2 push notifications within 5 seconds, will that trigger this kind of alert?
It means pretty much what it says. Apple is respectful of user's battery life and data consumption and recognises that a pass update is a high energy activity that the user has little control over, and so if a pass issuer makes too many updates, then iOS takes action to alert the device owner so they can choose if they would like to continue to receive these updates (at the expense of reduced battery life).
Apple's previous policy was to silently throttle updates, but this led to problems, since users were unaware that they were being throttled and would wonder why their passes were not updating.
Apple recognises that developers may need to push content more frequently, which is why you can disable rate limiting on your device via the developer menu (that appears when you have your iPhone hooked up to Xcode).
Apple doesn't publish the criteria that it uses to throttle, and normally a quick burst of activity (E.g. a one-off burst of 2 or 3 messages in the space of a few minutes) would be tolerated. But if the issuer is sending dozens of messages every few minutes, then you can almost certainly expect they will see this message.
App that I am working on is offering a VPN connection, that can run even when the app is not running at all. This service is paid, but also I would like to offer a free trial limited by session length and maximum data transfered.
The problem I've encoutered, is with monitoring the data trasnfered when the app is in background or not runing at all. So far the best solution I've came up with, would be to periodically run small task that checks if the user is still within the data limit and if not, the VPN will be disconnected and notification shown to the user.
Will silent notification get priority every time it will be required? According to this quote from developer.apple.com, they are low-priority which isn't what I need, but I was unable to find anything else.
Silent notifications are not meant as a way to keep your app awake in the background, nor are they meant for high priority updates. APNs treats silent notifications as low priority and may throttle their delivery altogether if the total number becomes excessive. The actual limits are dynamic and can change based on conditions, but try not to send more than a few notifications per hour.
How can this be done reliably? Is there any other way?
If this is a personal VPN connection (i.e. you're just providing a config to the standard system) and you're not in the flow, then this isn't possible. There is intentionally no "I want my program to run all the time" solution. Even if you come up with one, Apple will probably shut you down.
If you're writing an MDM/supervised VPN connection (i.e. you're providing a ...Flow object of your own), then you're already running all the time and you can just control it as you want. I'm assuming you have the former or you wouldn't be asking.
I believe you're doing this backwards. Monitor the session length on the server, and disconnect there. When you disconnect, send a push notification, which can display a message directly without having to open the app. That is both robust and the intended solution.
Periodically posting a silent notification to wake yourself up will definitely not work because Apple specifically does not want you to do that and they explicitly break it (as they note "silent notifications are not meant as a way to keep your app awake in the background"). It's bad for battery life. This is intended to be solved on your sever, on on the user's device.
My iOS app (which targets iOS 8.1+) use location services to determine if a user has entered a particular region during an event. Ideally I would like to enable the geofencing a little before the event and turn it off a little after the event completes. The problem is there is no guarantee the app is running an hour before the event so I turn on geofencing at the point the user registers for the event. This is not the best approach as it means the geofencing is on for much longer than it needs to be.
As far as I can tell, there is no way to "wake up" the app in the background at a scheduled time in iOS. I could use the push notification meant for updating content, but It's not clear to me if Apple would reject such a misuse of that notification.
Any suggestions?
I've been looking into this myself.
If you can arrange a push notification from your backend ("Silent push notification", aka "content-available"), it seems to be a good option. In real-world situations, this seems to give you the best control over the timing. Unfortunately, it won't work if the person doesn't have connectivity. Also, unfortunately, you need a backend that can queue events at a time (not just in response to an input.) If you have such a backend already, and your app is only useful to the user when they have network coverage anyway, this is probably the best option. It seems this an appropriate use of the technology, so Apple should approve.
Another option I'm trying is to use background fetch. You specify a "minimum interval" to avoid too much fetching. Try 50% of the remaining time-to-event as a minimum. Every time the app wakes up (whether in the foreground because the user opened it, or in the background because background-fetch opens it) you can calculate the time-to-next-event, update the fetch interval, or start the region monitoring. You are supposed to use "background fetch" to fetch information from a server, but there doesn't seem to be any requirement to poll a server, you could poll your internal data instead. I haven't fully tested this yet but it seems promising.
You can use significant location change monitoring, which I've read will wake up your app briefly every 15 minutes or less, and you can use the time/location information to decide whether to turn on the geofence. I think this would work well in combination with the above "background fetch": Many hours or days before the event you rely on background fetch, which you then use to turn on significant location change monitoring a few hours before the event. (There's speculation that geofencing is actually more battery efficient than significant change monitoring, but you could choose to assume that other apps on the user's device will already by watching for significant changes, in which case the marginal cost of your app adding itself to the list should be minimal.)
Putting them all together, you could create a sequence of
background fetch -> significant location monitoring -> geofencing
as the time gets closer.
There is also the CLVisit monitoring functionality, it's not understood very well, but supposedly uses less power and is called less frequently than significant location change monitoring. If the background fetch or silent remote notifications aren't working to wake up your app, give this a try, and please report back!
You can't (yet) do a silent content-available local notification (AFAICT). However, perhaps you can schedule up a local notification "Your event starts tomorrow" or something that convinces the user to click the option that starts the geofence. Here's a tutorial on it http://www.appcoda.com/local-notifications-ios8/, the response of action can be UIUserNotificationActivationMode.Background so your geofence can come on (if the user responds to the notification) without bringing the app to the foreground.
It's been 5 to 6 weeks since you asked, do you have your own answer already? Please let me know.
I have a background app with a UIBackgroundMode of location.
I would like my app to additionally contact a server every few or several hours to see if there is some new data for it (because using apple notification push would notify the user and that is not desirable).
Polling is something I would never use on any other OS, but with iOS they don't leave you much choice if there is certain functionality you would like to try to achieve.
If the polling interval is quite lengthy such as a few or several hours between polls, and the polling activity itself only lasts several seconds then the usual knee-jerk reaction about it draining battery life is greatly diminished.
Would a repeating NSTimer fire when an app is in background mode? If not is there another type of timer or mechanism available?
If it's just to check for new content, and not really time sensitive, you COULD use the significantChanges background location method...but if the user stayed fairly immobile it'd rarely/never fire. I would probably also add the update check in applicationWillEnterForeground to be more sure
No, that's not allowed. You should have a look at Push Notifications and find a server side solution.
I am doing Comet chat with Erlang. I only use one connection (long-polling) for the message transportation. But, as you know, the long-polling connection can not be stay connected all the time. Every time a new message comes or reaches the timeout, it will break and then connect to the server again. If a message is sent before the connection re-connected, it is a problem to keep the integrity of chat.
And also, if a user opens more than one window with Comet-chat, all the chat messages have to keep sync, which means a user can have lots of long-polling connections. So it is hard to keep every message delivered on time.
Should I build a message queue for every connection? Or what else better way to solve this?
For me seems simplest way to have one process/message queue per user connected to chat (even have more than one chat window). Than keep track of timestamp of last message in chat window application and when reconnect ask for messages after this timestamp. Message queue process should keeps messages only for reasonable time span. In this scenario reconnecting is all up to client. In another scenario you can send some sort of hart beats from server but it seems less reliable for me. It is not solving issue with other reason of disconnection than timeout. There are many variant of server side queuing as one queue per client, per user, per chat room, per ...