I've created an application which does synchronization with the server.
I've already have a code, which does synchronization once user pressed a button. Now it is time to add Service there.
I have the following questions with regards to the services on android:
will the service be started if user never run application before? (i.e. just installed that)
when the service will be started first time? can I start it from onCreate of the main application?
if user presses Synchronize button in the application, should I start that Service or should I have different process for the same? How can I check then that background synchronization is not happening at the same time?
should I use ASyncTask, even if the service is started as
startService(new Intent(this, ServiceSync.class));
The preferred approach to syncing data in Android is providing a SyncAdapter to perform the sync. You have a very nice summary of the required steps in this post.
You will also find these articles useful.
Edit:
1-2-3: You can use a bound service to manage the interaction and service methods from your activity. You have full working samples in the link provided. Basically, you bind to the service in your activity's onStart method and unbind onStop.
Remember that a service runs on the UI thread, so every time-consuming task such as fetching data over the network must be done in a separate thread.
4: You don't need an AsyncTask here.
Related
So basically what i am trying to do is i want a service that runs in background and updates the LatLong to the server. This operation needs to happen all the time even if the application is running or not.
Now when the application is launched i want the service to calculate the distance between the latlong and update the UI in addition to the work that it was already doing i.e. updating the latlong to the server. i want the service to do the additional work for multiple activities. lets say i launch the application and i am on Activity A, onclick of a button on Activity A the service starts updating the UI and when we click gain it stops updating. Now i am on Activity B and on click i want the service to do some work in addition to the updation of LatLong and update the UI.
What would be the best approach to achieve this.??
EDIT
The problem i am facing is not getting the service update the UI but making the activity communicate with the service when it has already started.
i can pass on some data when i am starting the service but how to communicate with the service when it has already started. How to tell the service that see you are already running and doing some operations now you have to perform some more operation on top of the previous operation.
I can make some static method in the service and call them when i need to perform the extra operation but i dont wanna do that.. i want to better approach.
Here is the basically services runs on the same main thread process as ui. When you want make it run continuously you have run it in your tread. In this way you avoid service being get stopped as application go in background or killed. (Please take look at Service.START_STICKY flag, this is what you need as i guess).
And more coming your second problem of activity getting updated with service information or data that is being collected for this you need look at " How Bind the service". (In activity check for service connection and Binding to a activity, Unbindibg is also there have look at it also). Activity has all the call backs for it you need to implement binder.
EDIT
Service to update ui has to have send and receive intent mechanism. You can broadcast and intent from the services check your activity is running or not. If running broadcast intent and have receiver in activity to listen it.
You can do it by interface mechanism too
There is some long processing that need to be completed, so I put it in a service. The activity must be able to connect to the service, show the user current results from the service. So I start the service with start Service and later call bind Service (with BIND_AUTO_CREATE) as in LocalService from http://developer.android.com/reference/android/app/Service.html#ServiceLifecycle. I want it to run until its job is done, and then self stop, even if client is still connected to it. (or determine the client to unbind) Is any way to do it with the sample LocalService?
I was considering passing a handler to the service so that it can send messages back to the activity, but I don't want the activity to get leaked. I am just getting used with services, so maybe I am misusing something.
EDIT: The workload consists of several threads, synchronized and run in parallel, so I guess is not a good candidate for intent service. Some data analysis is done in background service, and when the user restarts the activity that started the service, it should display some graphics according to current values computed by background service. All background processing is triggered at the beginning, and need only inspection later on, when activity connects to it. Android should not be able to stop the service. When the job is finished, the service should be able to terminate even if the activity is connected to it.
I just recorded a callback with the service. If the activity is not connected to service, it sets the callback to null. In this callback I call stopService() and then finish() on the activity. I am not sure that it is the best method, but it works fine for me.
If you want a service to be stopped when it is finished, I think what you are looking for is IntentService, they work as services, but run in another thread and when they are completed they dissappear.
Check this out
EDIT: NickT link is better, check that out! :)
I started learning android i've been playing with it and so far so good but i have some doubts about Services, i started learning them today so by gently if a say something very wrong.
For example, i want my app to grab some information over the internet from time to time, this polling period is defined by the user, then the UI gets updated. I though about creating a Service that run lets says every 30 minutes, gets the information and updates the UI.
If i get it right:
An IntentService just executes an operation and stops by itself sending the result through an intent(right?), so i think it's not what i want.
A Bounded Service is most likely used when you want IPC or allow binding from external apps, which again i think it's not what i want.
I think a Local Service is probably what i need, using a LocalBroadcastReceiver to update the UI, how can i make it to run the operation every X minutes( Handler postDelayed, ScheduledExecutorService or Alarm Manager ? )
If i understand it right a Service if not bounded can run infinitely if it's not killed due to low memory problems, making it a foreground Service is the safest ?
Last thing and it's kind of a noob doubt, if the user leaves the application(Click Home Button or opens other app) the app is still in background but the activities are in "Paused" or "Stopped" mode will the Service still be able to talk to them ?
Sorry for long post and thank you.
Your requirement : after every x minutes, start a service, pull some date, update UI.
Solution :
Define or set an alarm for every x minutes, to trigger a receiver.
From receiver start the service.
In the service, start an async task to fetch the data in doInBackGround().
Once data is fetched, from onPostExecute() send a broadcast to your activity.
In the activity have a dynamic receiver registered for broadcast sent from service.
From dynamic broadcast receiver update UI.
From what you've explained I wouldn't personally use a service.
The Android docs on services explain more but here is a snippet:
http://developer.android.com/guide/components/services.html
A Service is an application component that can perform long-running operations in the background and does not provide a user interface.
You could perhaps looks at using an AsyncTask, especially given that you only want it to run whilst the app is running:
http://developer.android.com/reference/android/os/AsyncTask.html
This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.
There is a good answer here on how to run an AsyncTask repeatedly at specific time intervals: How to execute Async task repeatedly after fixed time intervals
I need some help or suggestions regarding Background services.
Well I want to achieve this. I have an application with Some Views that application also has a Background Service that always keeps on running.
In my views there is a Button whenever I press that button, that button passes some files to the Background Service and my Background service upload that file onto some server.
I am done with the uploading process. Now I want to know that how can I make a Background Service that always keeps on running and on my tapping of the button it sends a file to the Service.
I am new in Background service implementation.
Please guide Friends with some tutorials, suggestions or guidelines.
Thanks a bunch
You've probably already read some of the Android Service documentation, but I suggest studying it further and looking at the Local Service Sample if you have not done so already:
http://developer.android.com/reference/android/app/Service.html
It sounds like you have already got your Service up and running, and I think the actual problem you are trying to solve now is how to communicate data from your Activity to your Service. When your Activity is bound with a Service that's part of the same application, that service is in the same process and runs on the same main UI thread, so once you get the IBinder object from the Service after binding with it, you can simply directly call the functions in that Service from your Activity. Similarly, you can pass your Service a handler object from your Activity so that the service can send messages or post Runnables to your Activity. Communication with a local Service is therefore quite simple.
So if you take a look at the Local Service Sample in the link above, you will see a section in the code where we get a reference to the Service once binding has completed:
mBoundService = ((LocalService.LocalBinder)service).getService();
After that point, it's possible to directly call methods on that Service that's in the same application. For example, you could have a method called sendFile in your Service. In your Activity, you might do something like:
mBoundService.sendFile( myStuffObject );
There are quite a number of questions on Stack Overflow regarding communicating between an Activity and a Service, and I think you'd find it beneficial to search and read these.
A standard Android service will do just fine in this case.
It will continue running in the background untill its work is finished or until you ask it to stop.
There is a topic on the android dev site explaining services in detail.
you should go for android Service that is used for Background operation . Inside the service your have use TimerTask which will be checking the Queue for every x sec and when any items present in the Queue it will pull the item and upload it to the server.
here is the link for Android Service..
http://developer.android.com/reference/android/app/Service.html
Link fro Queue.http://developer.android.com/reference/java/util/Queue.html
I have a service running in the background. Based on some condition it has to start some activity. Activity has to send back the response.
I did google search and found out we have to use Notification mechanism. But I am not clear how to send the response back from activity to the service running.
Also service is collecting sensor data(acclerometer, gps). So should activity be started in separate thread so that collecting sensor data is not affected.
Please clarify.
Activity would be started in main UI thread, instead, your long-running service should run in and manage its own thread, since according to the document, service is also created in main thread.
Basically the best way to communicate is to use Intent. This allows loose couple of sender/receiver (i.e., activity/service in your case). Intent is a large topic in terms of android, and yet it is one of the most fundamental one, I think you should look for tutorials online about it.
If your activity is opened and return the result after completing the task of Activity then you can use startActivityForResult and then return the result.
Using of notification is simple, just create a interface class, and implement the class in your service. When you need to send data back to service, you can just call the appropriate method with data.