We have multiple mobile clients (ios and android) subscribed to a channel-msg.
7 messages are being published to channel-msg by the server:
Messages 1-3 were published to channel.
The device got messages 1-3 via native PubNub.
The user turned the device off.
Messages 4-5 were published to channel.
The user turned the device on, and app in foreground.
Message 6 is published.
Message 6 arrives to the device.
At this point (in the "got PubNub message" callback in the device's code), I don't want to perform Message 6, because I must perform Messages 4-5 first.
I can use the history() API to get the lost messages, but with this strategy I am forced to perform the "history check" on each message I receive on the device, before I can execute it.
I there a better pattern/design to handle this scenario?
PubNub History
You don't need to call history for each individual message, rather, you retrieve all missed messages (up to 100 per history call).
Just save the timetoken of the last received message in a way that you can retrieve it when the app is relaunched (NSUserDefaults). When your app is launched, just use the timetoken as the end param (nil for start param) in your history call.
If you get 100 messages returned (the max) then it is likely you have more and you need to call history again (paging through storage) and again until you receive > 100 messages.
Once you have received the last of the messages, use the timetoken of that last message (the one closest to now), use that timetoken to subscribe to get any message between the last history call and your subscribe and continue to subscribe for further messages.
Related
I have a Cordova app that receives secure messages from a service provider, through our servers, to an app installed on a phone by the user. However, the app may be rarely used (in the order of 12 months or so). In the event that the provider needs to contact the user we currently send an FCM notification. The problem is that because we don't want to place any drain on the user's battery for a service that they rarely use (although is extremely valuable) then we don't try and run anything in the background - which means that according to the firebase document Lifetime of a message the message will be discarded if the user doesn't open the app for one month.
The referenced doc states:
If the device has not connected to FCM for more than one month, FCM still accepts the message but immediately discards it. If the device connects within four weeks of the last data message you sent to it, your client receives the onDeletedMessages() callback. The app can then handle the situation properly, typically by requesting a full sync from the app server.
How are we supposed to inform the user that there is a message for them?
I understand why such a precaution can make sense, but what options exist to allow us to receive the notification causing minimal impact on the users' device?
I have created an app that send messages between devices using GCM , the thing is
if i want to send several messages in a row its possible that one of the sent messages wont be sent instantly and will be delayed.
My scenario is : I have tried to send 3 messages in a row , i received the first and the third one but couldn't receive the second one !!
One day after I received the second message , how could this be possible ?
Is there any way to sync the sending ? and why it took the second message 24 hours to be received ?
Google is very clear about how you get no guarantee that a message will arrive at all.
In other words, don't depend on messages getting delivered. Your system needs to be robust enough to handle this. Perhaps periodically check. Definitely check if the backend has stored messages you did not receive yet.
If you purely rely on GCM delivering your (chat?) messages, then users will very quickly uninstall your app, because it will be faulty.
I am working on application were i need to send some data to specific user without much of delay.
Actualy I have more then 1000 users who are online out of those I want to select one user and send the data to him only.
I had two solution
1.current implementation=>
So far I am using push notification for this purpose I get the user's device Id and send notification to him but problem is push notification(sending/receiving) depend on my server and GCM
server so it get delayed sometime(I observed sometime it gets delayed by 5 min also).
2.Not implemented=>
Another option is to run thread continuously to check any msg is arrived, if arrived check if whether is meant for same user or not,if he is targeted user then show the data else discard .But here also problem is even if this msg dose not belong to that user one need to check the condition and then discard.
I am planning to implement Android push notification serivce for an app that might require receiveing even two messages per device per second. I would like to know if GCM Push messaging is the way to go or should I stick to SyncAdapter or some other technology? Single device will receive up to few thousand notifications per day. Message size will be very small to 4kb limit is fine.
If it is critical that all of the messages reach the device and none are lost, GCM alone is not the right choice, since in case GCM server would temporarily lose connection with a device, there's a limit to the number of messages that would be stored for later delivery for that device in the GCM server.
Therefore, if you have to update your app that frequently, you should probably keep an open connection between your server and your app, and load data from the server periodically.
Though the GCM server limits the number of messages that will be stored for later delivery in the case of a device disconnect, you can always create a collapse_key.
According to GCM documentation, if there is already a message with the same collapse key (and registration ID) stored and waiting for delivery, the old message will be discarded and the new message will take its place (that is, the old message will be collapsed by the new one).
Essentially, if you only need the most recent push notifications rather than all prior sent, GCM is acceptable for sending push notifications with high frequency.
You can read more about this in the GCM Advanced Topics.
I have successfully implemented the android push notification using google c2dm.
the problem is,when i push the message from the server i am getting success full deveice id. but the device some time receive push message,some time did not receive.(wifi is fully active)
i want the app to receive all the push message with out any push message lose,becoz each notification is important.
Is there any special parameter need to set or hw i would i confirm that device successfully received the message.
"C2DM makes no guarantees about delivery or the order of messages. So, for example, while you might use this feature to tell an instant messaging application that the user has new messages, you probably would not use it to pass the actual messages."
But you can try to play with 2 parameters:
collapse_key
An arbitrary string that is used to collapse a group of like messages when the device is offline, so that only the last message gets sent to the client. This is intended to avoid sending too many messages to the phone when it comes back online. Note that since there is no guarantee of the order in which messages get sent, the "last" message may not actually be the last message sent by the application server. Required.
delay_while_idle
If included, indicates that the message should not be sent immediately if the device is idle. The server will wait for the device to become active, and then only the last message for each collapse_key value will be sent. Optional.