Develop Reference

Android force traffic over internet while WiFi enabled

I'm starting to write an Android application to perform background monitoring of my web server. With WiFi enabled a problem will be that traffic is directed over that by default, I'd like to always use 3G for the HTTP request to check external availability as well. I know I could use this code to disable WiFi programmatically:
WifiManager wifiManager = (WifiManager)getBaseContext().getSystemService(Context.WIFI_SERVICE);
wifiManager.setWifiEnabled(false);
But as it will be running in the background it's a bit clumsy and will interrupt other operations over WiFi while the check is in progress. Looking at the Socket Documentation I can't see any apparent way to achieve this. I'm wondering if there's any supported way to achieve this on a non-rooted phone? I have full control over the server so the protocol doesn't specifically have to be HTTP.

This seems like it would be an awfully dangerous feature for Android to allow.
What about users who are on metered 3G plans? How would they feel if an app forced them to use a 3G connection and then bugged out or something and blew away their whole data quota without them even knowing it (thinking they were on WiFi)?
Also, there could not be more than one active networks at a time.
Possible Resolutions-
What you can do is to force disable the wifi network, when your application is active and then enable it later.
Also, Try searching for a method called requestRouteToHost. It allows you to specify the network type and the host you want to find a route to.

I don't believe you can do this in android since only one network connection is active at any given time. A similar question is posted here as well:
Send HTTP request through 3G network without using WiFi?

Android - automatically start a service when joining a specific wifi network

I am trying to build an application/service that will execute some coding everytime I connect to a specific wifi network (to log into that network and then keep the connection active ). I do already have the code for the login part and it is working fine, but I don't really know how I can automatically run this code when I connect to a network.
Ideally, I would like to build a service that starts when I join a specific wifi network, keeps the connection active (like makes a request every 10 min to keep the connection active) and finally stops when I leave that network.
I know how to build the service and keep it active, but don't know how to start and stop it automatically when joining / leaving a wifi network. Any suggestions on how to do this is appreciated. If my approach is not correct and there is a better/simpler way to do that, please let me know
Regards,
Marcel

you need a broadcast receiver.
this broadcast receiver will receives broadcasts of Wifi connected and wifi disconnected actions and from there you can start and stop your service.

Implement a BroadcastReceiver listening for the scan results from WifiManager.startScan()
Have a look at Android Scan for Wifi networks

Force internet connection attempt?

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.

Approach to handle WiFi disconnects

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.

Android Froyo and Wifi

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.