Develop Reference

Android - stop and restart app on network connection

My Android app successfully detects when the network disconnects and reconnects. The app successfully stops all appropriate services and moves the app to the background (but still in the application list) upon network disconnect as desired. By the way I am using sharedprefs to save my application data and onSavedInstance for rotation refresh.
When the network is reconnected my app detects the reconnect but where I am stuck is how to properly restart my app and and all related services. I tried the low hanging fruit such as just calling onCreate(bundle) or onResume() from my network detect routine. These do not appear to initialize and restart everything needed and the app does not come back to the foreground as desired.
What is the ideal way to restart my app and bring it back to the foreground upon network reconnect?
I recognize other posts contains bits/pieces of the above but I have yet find an answer to my second question, " What is the ideal way to restart my app and bring it back to the foreground upon network reconnect? "

Android Websocket Service Persistent Connection

I implemented a chat application in Android with websockets. However when the user closes the application, the websocket connection to the server is lost and no new messages can be received.
I am essentially lost and do not know where else to turn, how can I setup the service in the app to stay connected to the server as the user logs in as well as after the app has been stopped?

As we're all aware, continuous background code execution is not feasible on Android; different ROMs will man-handle your background services without any guarantees (e.g. START_STICKY will not get your service restarted on some devices), so we need to do the best we can with the code that is reliably executed.
In this situation, you have a websocket server delivering continous information to your client. When your app is in the background, it may miss out on some data. When your app returns to the foreground, your information may be out of sync, so you need to synchronize again with your server, and then reconnect to your websocket.
In my chat app I achieve this by checking whether my websocket service is running onResume in an activity which is a superclass of all the activities that I want to have access chatting data (i.e. not login/registration activities). If the service is not running, I synchronize my data by pulling the changes from an endpoint and then restarting the service. This way, even if the service is killed in the background I will still get the latest data and real-time experience once the app returns to the foreground.

Should you connect and disconnect to Google Play Services in each activity?

I am writing an application which needs a connected location client in all the activities. How do the manage the state of the client?
I want to call the mLocationClient.connect() only once to avoid hassle, and should be able to remove location updates / disconnect when the application stops.
How do I keep the location client connected across all activities, assuming I have connected to it in the splash screen Activity?
Another question that arises here is, when I resume the paused application (not recreation), the app won't start with the splash screen. How do I maintain the connection in this case?
Thanks in advance.

What you need is a bound service: these services only live while a client (like one of your activities) is connected to it. This allows you to have a shared state (a single connected location client) while still ensuring that you connect/disconnect appropriately.
In this situation, any location aware activity would bind to the service. When the first activity (say, your splash screen activity) binds to the service, the service would start and connect to Google Play Services. Your service's Binder would then give access to its LocationClient to any connected activities. As you move between activities, each would bind to the service in turn and be able to get the current location data and each would as they get destroyed.
When the user exits your application (i.e., the last activity is destroyed), then the service would automatically stop itself, allowing you to disconnect from Google Play Services.
As long as you bind to the service from every activity that needs location data, it doesn't matter which activity starts the service initially: the service would just connect if needed.

Multiple background services with one ongoing notification

I am writing an app that connects to a Bluetooth device, continuously receives data from it, and stores in local db. Certain data received requires system alert to pop up. There is a main activity which just displays the status of connection and data received. It all works just fine so far, including the popups.
Since the app requires to be run in background I have implemented a "bluetooth connection" service that manages the BT connectivity, and displays ongoing notification in order to avoid being killed. For coding clarity reasons I would like separate background service to collect all data, and log it (instead of having BT service do all the work). I also prefer loose coupling between my app components, so am using GreenRobot's event bus for all IPC. As a result my BT connection service is completely unaware of any data collection/logging code - it just dispatches a message to event bus and I'd like to keep it that way.
Now I'd like to have my data collection/logging code to be run as another background service. Is there a way to ensure it runs as long as BT connection service is running? And without displaying yet another ongoing notification or tightly coupling the code between two services?

You could let your class extend service so in this case you dont have to make a notification for it. Basically it keep running in the background without the need of displaying notification on the status bar. Make sure before you exit your app to stopservice() otherwise it will keep running until the device restarted or in somehow the user force stop your app from application manager inside of the settings.

Which background model to run

I am trying to develop an application which will require a service to
run in the background. I am relatively new to android programming,
and after reading many posts, blogs, how-to's and books on creating
and managing services, I am still pretty confused about which model I
should try to use.
First, let me present (in general) the application requirements: I
need an application which will spawn a background process (service?)
which will connect to a bluetooth device. The bluetooth device is
designed to deliver data to the android device. The issue is that the
data could come in at any moment, so the bluetooth connection has to
stay active. Note that the application is a VERY SPECIFIC app and is
NOT intended for public use. I do understand the arguments for not
having background apps running all the time, but please understand
that this is a very specific application for a very specific client.
Now, in general, I think the program flow would be to start the
application (and launch a UI activity). Then I need to configure and
connect to the bluetooth device. At this point, the user should be
able to do other things - make phone calls, check their email, etc.,
while the bluetooth connection is still active and potentially
receiving data. If data comes in, a notification is fired, etc.
So here are my questions and concerns:
If I start an app (which spawns a UI activity and ultimately my
bluetooth connection service) but the app is killed, apparently, the
service handling the bluetooth connection is killed as well. How can
I keep that alive? I read that Service.setForeground() was
depricated, but even if I were to set it to the foreground, if the app
is killed, the service is killed as well. I need to have it run in
the background with as high of a priority as possible (again, I do
understand that this is considered "bad form", but this is a specific
app and this functionality has been requested by the client).
If I started the app (and the service, etc.), but the user, say,
answers a phone call, the app is put into the background. However,
let's say the user goes back to the home screen and starts a DIFFERENT
instance of the app, i.e., he doesn't hold down the home key to select
the already running app from the task manager but starts a completely
new one. If the service handling the bluetooth connection is still
running, how will this new instance behave? i.e., how can I get it to
connect to the bluetooth service which is ALREADY running in the FIRST
instance of the app instead of this new instance? Do I have to use
some form of a Remote service instead of a local service? This is
where I'm a little confused by things as it seems remote services and
defining an AIDL seems to create a lot of extra overhead, and since
I'm already creating a lot of overhead with the service running in the
background all the time, I want to keep that as small as possible.
How can I insure I am connecting to the same service already running?

1)
The service does not depend on an Activity. You can have it running on the background until you call stopSelf().
You can have a BroadcastReceiver that listens to the android.intent.action.BOOT_COMPLETED so your service is started when the phone is turned on.
2)
Your Activity should bind to the service. And get the info from it.
Check this question.