By default, Wifi sleep policy is "Sleep on screen idle".
With this policy, is it possible for a Background Service at a later time to wake up Wifi using some API?
Am trying the following, but does not work:
When my Background Service wakes up, it calls "ConnectivityManager.getActiveNetworkInfo()" to get active network.
Since, the wireless is off on idle, I tried waking it up using "WifiManager.startScan" on a previously used Wifi connection.
But still dont get Wifi connectivity.
Any ideas?
I preferably do not want to change my sleep policy to "Never".
Thanks
Hemant
There are no real simple solutions for this. To with a high probability ensure you have WIFI connectivity when the phone/screen goes to sleep the best way is to turn it off. Look here for a lot of details - http://wififixer.wordpress.com/
It is important to realize that in sleep mode the Wifi enters a low power mode. This will become tricky then to programmatically check as it might have connectivity to the Wifi but the Wifi connection is too weak or too slow to complete the HTTP request and hence it times out. This would force you to also check the speed of the Wifi connectivity as well as you will have an active network but a pretty lousy one.
Proper handling of the escaping when timeout occurs for the HTTP call you make makes it ok to use but ultimately the only way to have a background thread constantly running to get data is only doable when you have the Wifi mode to never sleep.
It is tricky and not the best way I know. :-( It is however the only path I have found which is reliable enough.
Related
My app is pinned and after waking up device all network requests that are made right away fail with a connection timeout. Waiting a couple of 100ms or seconds does the trick and everything works normally after that.
I suppose there's a small window of time when wifi is "re-enabled". Whats the best way to detect that event?
Android version 4.4 and wifi sleep is set to "never"
As Augusto Ferrarini points out you can listen for broadcast and handle it accordingly. There is a chapter about it on developer.android which I'd recommend reading together with the link from Augusto Ferrarini.
I have a service which polls every hour attempts to sync data automatically to the web from the device.
I have it working but I need to find a way to establish an internet connection if there is not one available.
For example - If my phone is in standby mode (screen locked for a period of time) the internet connection is dropped and it is unable to sync when it needs to.
I would like to attempt to connect via wifi if available, then using 3G if required.
Is there a reliable way to do this?
UPDATE -
I found an article online which uses this code to attempt connection via 3G if there is no wifi available :
int resultInt = connectivityManager.startUsingNetworkFeature(ConnectivityManager.TYPE_MOBILE, "enableHIPRI");
unfortunately it doesn't seem to work on all devices, maybe I need to try other options than "enableHIPRI" ??
Any ideas?
OK, although I haven't been able to solve this problem I have discovered that the main cause for the delay in between sync attempts is because the cpu gets stopped during sleep mode, this means my timer task was paused..
My workaround was to rewrite the service using a wakeful intent to get around the timer issue.
This makes my solution much more reliable so I am closing this question! :)
You should be able to do most of that using ConnectivityManager. It allows you to query the available types of networks and using requestRouteToHost you should be able to ensure there's a connection set up that you need for syncing.
I think you cannot rely on such thing on mobile phone, as in any embedded device you cannot be sure if the device will connect and stay connected when you want. You can only leave a message for the user that data was not synchronized or try to minimize it by checking if there is connection and then synchronizing not just in one hour.
My objective is to be able to scan changes in Wi-Fi networks (mainly to check what networks are available). Right know I'm doing it by registering a reciever:
registerReceiver(wifiReceiver, new IntentFilter(WifiManager.RSSI_CHANGED_ACTION));
where WifiReceiver is my BroadcastReceiver.
The problem is that it works only when the phone is on. As soon as it goes to sleep mode (either by pushing the power button or after some time), the receiver stops receiving. I already acquired a wake lock in onCreate of my main class and releasing it in onDestroy (it's a partial wake lock). Additionally I've tried this:
Settings.System.putInt(getContentResolver(),Settings.System.WIFI_SLEEP_POLICY, Settings.System.WIFI_SLEEP_POLICY_NEVER);
to keep wifi from sleeping. Unfortunately that didn't help.
Is there any possibility to scan for network changes, even when phone is asleep? I want to be able to check what networks are in range (by SSID). Maybe I should use another action?
Appreciate your help.
Literally, no, the hardware isn't typically designed nor the low level drivers written to allow wifi to operate while the application CPU is in sleep mode - unlike the case with the mobile network interface which is intended to receive push events like phone calls, sms, and gmail "tickles".
So your choices are to either manage to successfully prevent the device from sleeping (good bye battery) or wake up periodically using an alarm, kick the wifi active, and poll the situation (still not good for battery life, but not as drastically so).
I'm afraid this sleep behaviour is managed by the system under (on Android 2.3.4) Settings > Wireless & Networks > Wi-Fi Settings > Press Menu > Advanced > Wi-Fi Sleep policy.
This could actually go against the users will, careful with that.
However I think there has to be a way to modify this param. programmatically, using this settings : Settings.System, and of course the corresponding permission in your manifest.
Like many apps my app depends on WIFI and Http Connection to operate. What I am not clear on is how I can time a wait until WIFI is enabled AND device is attached to WIFI network is. What is the best way to delay on application startup long enough for this to happen? during this time I would for example keep buttons deactivated. Also is there any way to make the device attempt to connect to its preferred network? Thanks
Take a look at ConnectivityManager and WiFiManager. Using these you can get events when network state changes
Use WifiManager to get the state of the connection.
Generally you will have to try. A Wifi connection can show as connected but not be able to actually send/receive because the signal is too weak. Once the connection is up, the app should try connecting and only when it succeeds, the buttons should be activated and so forth.
In my Android application, it is
noticed that when the device goes to sleep/standby WiFi is
disconnected. When the device wakes up, it gets reconnected. Before making a
httpClient.execute(..) call to remote server we check if the device is connected to n/w.
When the data transfer is being done and if
the device goes to sleep then Android runtime will switch to another
medium for connectivity(3G,GPRS etc.).
Is the switch from WiFi to alternate cellular service
say 3G, seamless?
How do I wait for WiFi to become available again? Should I use Thread.sleep(delay) when the WiFi wakes up? I have seen broadcast actions when the WiFi state changes.
In general, what is the ideal approach to handling WiFi disconnects in a mobile app?
Why not use WifiManager.WifiLock when the transfer is happening and release it when you have finished.
I would suspect network connection switch would not be seamless. I don't know for sure.
A BroadcastReceiver will let you know when Wifi connection state changes. Have a look at ConnectivityManager though because that will monitor Wifi and GPRS etc and it does do failover. Whether it is seamless though I don't know.