Related
If I have an app that does not have any activities, just one BOOT_COMPLETED broadcast receiver and the simplest service. The receiver will just start the service and the service will just ran the following code:
public class ScreenStateService extends Service {
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
return START_STICKY;
}
#Override
public void onCreate() {
super.onCreate();
}
}
As as I understand, the service would ran until the end of time or until one of the following scenarios occurr:
Low memory: The system is running low on memory so it decides to stop the service.
ANR
The user manually stops the application or disables it.
In 1 and 2 the system would start the service again, after memory is no longer low or after the error is handled. In the case of 3 it wont be started again.
The question is: is the above right? Are there any other cases where the service would be stopped by an outside source? Please specify if it would be started again automatically if there are any.
I am starting a service from my main Android activity as follows:
final Context context = base.getApplicationContext();
final Intent intent = new Intent(context, MyService.class);
startService(intent);
When I close the activity page by swiping it out from the recent apps list, the service stops running and restarts after some time. I can't use persistent services with notifications because of my app requirements. How can I make the service NOT restart or shutdown and just keep on running on app exit?
I'm in the same situation, so far I learned when the app is closed the service get closed also because they are in a one thread, so the service should be on another thread in order fot it not to be closed, look into that and look into keeping the service alive with alarm manager here an example http://www.vogella.com/articles/AndroidServices/article.html this way your service won't be shown in notification.
lastly, after all the research I've done I'm coming to realize that the best choice for a long running service is startForeground(), because it is made for that and the system actually deals with your service well.
make you service like this in your Mainifest
<service
android:name=".sys.service.youservice"
android:exported="true"
android:process=":ServiceProcess" />
then your service will run on other process named ServiceProcess
if you want make your service never die :
onStartCommand() return START_STICKY
onDestroy() -> startself
create a Deamon service
jin -> create a Native Deamon process, you can find some open-source projects on github
startForeground() , there is a way to startForeground without Notification ,google it
Services are quite complicated sometimes.
When you start a service from an activity (or your process), the service is essentially on the same process.
quoting from the developer notes
Most confusion about the Service class actually revolves around what it is not:
A Service is not a separate process. The Service object itself does not imply it is running in its own process; unless otherwise specified, it runs in the same process as the application it is part of.
A Service is not a thread. It is not a means itself to do work off of the main thread (to avoid Application Not Responding errors).
So, what this means is, if the user swipes the app away from the recent tasks it will delete your process(this includes all your activities etc).
Now, lets take three scenarios.
First where the service does not have a foreground notification.
In this case your process is killed along with your service.
Second where the service has a foreground notification
In this case the service is not killed and neither is the process
Third scenario
If the service does not have a foreground notification, it can still keep running if the app is closed. We can do this by making the service run in a different process.
(However, I've heard some people say that it may not work. left to you to try it out yourself)
you can create a service in a separate process by including the below attribute
in your manifest.
android:process=":yourService"
or
android:process="yourService" process name must begin with lower case.
quoting from developer notes
If the name assigned to this attribute begins with a colon (':'), a new process, private to the application, is created when it's needed and the service runs in that process. If the process name begins with a lowercase character, the service will run in a global process of that name, provided that it has permission to do so. This allows components in different applications to share a process, reducing resource usage.
this is what I have gathered, if anyone is an expert, please do correct me if I'm wrong :)
This may help you. I may be mistaken but it seems to me that this is related with returning START_STICKY in your onStartCommand() method. You can avoid the service from being called again by returning START_NOT_STICKY instead.
The Main problem is in unable to start the service when app closed, android OS(In Some OS) will kill the service for Resource Optimization, If you are not able to restart the service then call a alarm manger to start the receiver like this,Here is the entire code, This code will keep alive ur service.
Manifest is,
<service
android:name=".BackgroundService"
android:description="#string/app_name"
android:enabled="true"
android:label="Notification" />
<receiver android:name="AlarmReceiver">
<intent-filter>
<action android:name="REFRESH_THIS" />
</intent-filter>
</receiver>
IN Main Activty start alarm manger in this way,
String alarm = Context.ALARM_SERVICE;
AlarmManager am = (AlarmManager) getSystemService(alarm);
Intent intent = new Intent("REFRESH_THIS");
PendingIntent pi = PendingIntent.getBroadcast(this, 123456789, intent, 0);
int type = AlarmManager.RTC_WAKEUP;
long interval = 1000 * 50;
am.setInexactRepeating(type, System.currentTimeMillis(), interval, pi);
this will call reciver and reciver is,
public class AlarmReceiver extends BroadcastReceiver {
Context context;
#Override
public void onReceive(Context context, Intent intent) {
this.context = context;
System.out.println("Alarma Reciver Called");
if (isMyServiceRunning(this.context, BackgroundService.class)) {
System.out.println("alredy running no need to start again");
} else {
Intent background = new Intent(context, BackgroundService.class);
context.startService(background);
}
}
public static boolean isMyServiceRunning(Context context, Class<?> serviceClass) {
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);
if (services != null) {
for (int i = 0; i < services.size(); i++) {
if ((serviceClass.getName()).equals(services.get(i).service.getClassName()) && services.get(i).pid != 0) {
return true;
}
}
}
return false;
}
}
And this Alaram reciver calls once when android app is opened and when app is closed.SO the service is like this,
public class BackgroundService extends Service {
private String LOG_TAG = null;
#Override
public void onCreate() {
super.onCreate();
LOG_TAG = "app_name";
Log.i(LOG_TAG, "service created");
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i(LOG_TAG, "In onStartCommand");
//ur actual code
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
// Wont be called as service is not bound
Log.i(LOG_TAG, "In onBind");
return null;
}
#TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
#Override
public void onTaskRemoved(Intent rootIntent) {
super.onTaskRemoved(rootIntent);
Log.i(LOG_TAG, "In onTaskRemoved");
}
#Override
public void onDestroy() {
super.onDestroy();
Log.i(LOG_TAG, "In onDestroyed");
}
}
From Android O, you cant use the services for the long running background operations due to this, https://developer.android.com/about/versions/oreo/background . Jobservice will be the better option with Jobscheduler implementation.
try this, it will keep the service running in the background.
BackServices.class
public class BackServices extends Service{
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
// Let it continue running until it is stopped.
Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
return START_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
}
}
in your MainActivity onCreate drop this line of code
startService(new Intent(getBaseContext(), BackServices.class));
Now the service will stay running in background.
Using the same process for the service and the activity and START_STICKY or START_REDELIVER_INTENT in the service is the only way to be able to restart the service when the application restarts, which happens when the user closes the application for example, but also when the system decides to close it for optimisations reasons. You CAN NOT have a service that will run permanently without any interruption. This is by design, smartphones are not made to run continuous processes for long period of time. This is due to the fact that battery life is the highest priority. You need to design your service so it handles being stopped at any point.
You must add this code in your Service class so that it handles the case when your process is being killed
#Override
public void onTaskRemoved(Intent rootIntent) {
Intent restartServiceIntent = new Intent(getApplicationContext(), this.getClass());
restartServiceIntent.setPackage(getPackageName());
PendingIntent restartServicePendingIntent = PendingIntent.getService(getApplicationContext(), 1, restartServiceIntent, PendingIntent.FLAG_ONE_SHOT);
AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
alarmService.set(
AlarmManager.ELAPSED_REALTIME,
SystemClock.elapsedRealtime() + 1000,
restartServicePendingIntent);
super.onTaskRemoved(rootIntent);
}
Why not use an IntentService?
IntentService opens a new Thread apart from the main Thread and works there, that way closing the app wont effect it
Be advised that IntentService runs the onHandleIntent() and when its done the service closes, see if it fits your needs.
http://developer.android.com/reference/android/app/IntentService.html
Best solution is to use the sync Adapter in android to start the service. Create a Sync Adapter and call start service their.. inside onPerformSync method. to create sync Account please refer this link https://developer.android.com/training/sync-adapters/index.html
Why SyncAdapter? Ans: Because earlier you used to start the service using your App context. so whenever your app process get killed (When u remove it from task manager or OS kill it because of lack of resources ) at that time your service will also be removed. SyncAdapter will not work in application thread.. so if u call inside it.. service will no longer be removed.. unless u write code to remove it.
<service android:name=".Service2"
android:process="#string/app_name"
android:exported="true"
android:isolatedProcess="true"
/>
Declare this in your manifest. Give a custom name to your process and make that process isolated and exported .
Running an intent service will be easier. Service in creating a thread in the application but it's still in the application.
Just override onDestroy method in your first visible activity like after splash you have home page and while redirecting from splash to home page you have already finish splash. so put on destroy in home page. and stop service in that method.
I am starting a service from my main Android activity as follows:
final Context context = base.getApplicationContext();
final Intent intent = new Intent(context, MyService.class);
startService(intent);
When I close the activity page by swiping it out from the recent apps list, the service stops running and restarts after some time. I can't use persistent services with notifications because of my app requirements. How can I make the service NOT restart or shutdown and just keep on running on app exit?
I'm in the same situation, so far I learned when the app is closed the service get closed also because they are in a one thread, so the service should be on another thread in order fot it not to be closed, look into that and look into keeping the service alive with alarm manager here an example http://www.vogella.com/articles/AndroidServices/article.html this way your service won't be shown in notification.
lastly, after all the research I've done I'm coming to realize that the best choice for a long running service is startForeground(), because it is made for that and the system actually deals with your service well.
make you service like this in your Mainifest
<service
android:name=".sys.service.youservice"
android:exported="true"
android:process=":ServiceProcess" />
then your service will run on other process named ServiceProcess
if you want make your service never die :
onStartCommand() return START_STICKY
onDestroy() -> startself
create a Deamon service
jin -> create a Native Deamon process, you can find some open-source projects on github
startForeground() , there is a way to startForeground without Notification ,google it
Services are quite complicated sometimes.
When you start a service from an activity (or your process), the service is essentially on the same process.
quoting from the developer notes
Most confusion about the Service class actually revolves around what it is not:
A Service is not a separate process. The Service object itself does not imply it is running in its own process; unless otherwise specified, it runs in the same process as the application it is part of.
A Service is not a thread. It is not a means itself to do work off of the main thread (to avoid Application Not Responding errors).
So, what this means is, if the user swipes the app away from the recent tasks it will delete your process(this includes all your activities etc).
Now, lets take three scenarios.
First where the service does not have a foreground notification.
In this case your process is killed along with your service.
Second where the service has a foreground notification
In this case the service is not killed and neither is the process
Third scenario
If the service does not have a foreground notification, it can still keep running if the app is closed. We can do this by making the service run in a different process.
(However, I've heard some people say that it may not work. left to you to try it out yourself)
you can create a service in a separate process by including the below attribute
in your manifest.
android:process=":yourService"
or
android:process="yourService" process name must begin with lower case.
quoting from developer notes
If the name assigned to this attribute begins with a colon (':'), a new process, private to the application, is created when it's needed and the service runs in that process. If the process name begins with a lowercase character, the service will run in a global process of that name, provided that it has permission to do so. This allows components in different applications to share a process, reducing resource usage.
this is what I have gathered, if anyone is an expert, please do correct me if I'm wrong :)
This may help you. I may be mistaken but it seems to me that this is related with returning START_STICKY in your onStartCommand() method. You can avoid the service from being called again by returning START_NOT_STICKY instead.
The Main problem is in unable to start the service when app closed, android OS(In Some OS) will kill the service for Resource Optimization, If you are not able to restart the service then call a alarm manger to start the receiver like this,Here is the entire code, This code will keep alive ur service.
Manifest is,
<service
android:name=".BackgroundService"
android:description="#string/app_name"
android:enabled="true"
android:label="Notification" />
<receiver android:name="AlarmReceiver">
<intent-filter>
<action android:name="REFRESH_THIS" />
</intent-filter>
</receiver>
IN Main Activty start alarm manger in this way,
String alarm = Context.ALARM_SERVICE;
AlarmManager am = (AlarmManager) getSystemService(alarm);
Intent intent = new Intent("REFRESH_THIS");
PendingIntent pi = PendingIntent.getBroadcast(this, 123456789, intent, 0);
int type = AlarmManager.RTC_WAKEUP;
long interval = 1000 * 50;
am.setInexactRepeating(type, System.currentTimeMillis(), interval, pi);
this will call reciver and reciver is,
public class AlarmReceiver extends BroadcastReceiver {
Context context;
#Override
public void onReceive(Context context, Intent intent) {
this.context = context;
System.out.println("Alarma Reciver Called");
if (isMyServiceRunning(this.context, BackgroundService.class)) {
System.out.println("alredy running no need to start again");
} else {
Intent background = new Intent(context, BackgroundService.class);
context.startService(background);
}
}
public static boolean isMyServiceRunning(Context context, Class<?> serviceClass) {
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);
if (services != null) {
for (int i = 0; i < services.size(); i++) {
if ((serviceClass.getName()).equals(services.get(i).service.getClassName()) && services.get(i).pid != 0) {
return true;
}
}
}
return false;
}
}
And this Alaram reciver calls once when android app is opened and when app is closed.SO the service is like this,
public class BackgroundService extends Service {
private String LOG_TAG = null;
#Override
public void onCreate() {
super.onCreate();
LOG_TAG = "app_name";
Log.i(LOG_TAG, "service created");
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i(LOG_TAG, "In onStartCommand");
//ur actual code
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
// Wont be called as service is not bound
Log.i(LOG_TAG, "In onBind");
return null;
}
#TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
#Override
public void onTaskRemoved(Intent rootIntent) {
super.onTaskRemoved(rootIntent);
Log.i(LOG_TAG, "In onTaskRemoved");
}
#Override
public void onDestroy() {
super.onDestroy();
Log.i(LOG_TAG, "In onDestroyed");
}
}
From Android O, you cant use the services for the long running background operations due to this, https://developer.android.com/about/versions/oreo/background . Jobservice will be the better option with Jobscheduler implementation.
try this, it will keep the service running in the background.
BackServices.class
public class BackServices extends Service{
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
// Let it continue running until it is stopped.
Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
return START_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
}
}
in your MainActivity onCreate drop this line of code
startService(new Intent(getBaseContext(), BackServices.class));
Now the service will stay running in background.
Using the same process for the service and the activity and START_STICKY or START_REDELIVER_INTENT in the service is the only way to be able to restart the service when the application restarts, which happens when the user closes the application for example, but also when the system decides to close it for optimisations reasons. You CAN NOT have a service that will run permanently without any interruption. This is by design, smartphones are not made to run continuous processes for long period of time. This is due to the fact that battery life is the highest priority. You need to design your service so it handles being stopped at any point.
You must add this code in your Service class so that it handles the case when your process is being killed
#Override
public void onTaskRemoved(Intent rootIntent) {
Intent restartServiceIntent = new Intent(getApplicationContext(), this.getClass());
restartServiceIntent.setPackage(getPackageName());
PendingIntent restartServicePendingIntent = PendingIntent.getService(getApplicationContext(), 1, restartServiceIntent, PendingIntent.FLAG_ONE_SHOT);
AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
alarmService.set(
AlarmManager.ELAPSED_REALTIME,
SystemClock.elapsedRealtime() + 1000,
restartServicePendingIntent);
super.onTaskRemoved(rootIntent);
}
Why not use an IntentService?
IntentService opens a new Thread apart from the main Thread and works there, that way closing the app wont effect it
Be advised that IntentService runs the onHandleIntent() and when its done the service closes, see if it fits your needs.
http://developer.android.com/reference/android/app/IntentService.html
Best solution is to use the sync Adapter in android to start the service. Create a Sync Adapter and call start service their.. inside onPerformSync method. to create sync Account please refer this link https://developer.android.com/training/sync-adapters/index.html
Why SyncAdapter? Ans: Because earlier you used to start the service using your App context. so whenever your app process get killed (When u remove it from task manager or OS kill it because of lack of resources ) at that time your service will also be removed. SyncAdapter will not work in application thread.. so if u call inside it.. service will no longer be removed.. unless u write code to remove it.
<service android:name=".Service2"
android:process="#string/app_name"
android:exported="true"
android:isolatedProcess="true"
/>
Declare this in your manifest. Give a custom name to your process and make that process isolated and exported .
Running an intent service will be easier. Service in creating a thread in the application but it's still in the application.
Just override onDestroy method in your first visible activity like after splash you have home page and while redirecting from splash to home page you have already finish splash. so put on destroy in home page. and stop service in that method.
Application thread get close if its killed by task manager. Need to re-invoke application as though its killed by other application or task manager. Any idea?
You have to run background service with START_STICKY command.
Just extends Service and override onCommand like this :
#Override
public int onStartCommand(Intent intent,int flags,int startId) {
super.onStartCommand(intent, flags, startId);
return START_STICKY;
}
Like this your Service is restart when it's close (by system or anything else)
You just have now check on your service (onCreate for example) if application is running or not and launch it again if not. I suppose PackageManager let you check this or simply put a static boolean is_alive to see if your activity is always running.
Regards
Jim
Bug in Android 2.3 with START_STICKY
I needed to keep alive a Service with all my forces. If the service is running anytime you can pop the UI.
onDestroy()
it will re-launch.
Can't be uninstalled the app, because it has a Device Administrator.
It is a kind of parental control, the user knows it is there.
Only way to stop is to remove the Device Admin, and uninstall it, but removing Device Admin will lock the phone as Kaspersky how it does.
There are a loot of braodcast receivers, such as boot finshed, user presen, screen on, screen off... , many other, all starting the service, you can do it with UI too. Or in the service check if your activity alive , visible, if not, than pop it.
I hope you will use with good reason the info!
Edit: Restart service code snippet:
// restart service:
Context context = getApplicationContext();
Intent myService = new Intent(context, MyService.class);
context.startService(myService);
Edit2: add spippet to check if the service is running in ... a load of Broadcasts
public static boolean isMyServiceRunning(Context context) {
ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
if (MyService.class.getName().equals(service.service.getClassName())) {
Log.d("myTag", "true");
return true;
}
}
Log.d("myTag", "false");
return false;
}
Edit3 other service start:
public static void startTheService(Context context) {
Intent myService = new Intent(context, MyService.class);
context.startService(myService);
}
Dont't forget Android 2.3 bug: do the logic for initialization in
#Override
public void onCreate()
and not in:
#Override
public int onStartCommand(Intent intent, int flags, int startId)
While look at Google IO official product source code I have found the following
((AlarmManager) context.getSystemService(ALARM_SERVICE))
.set(
AlarmManager.RTC,
System.currentTimeMillis() + jitterMillis,
PendingIntent.getBroadcast(
context,
0,
new Intent(context, TriggerSyncReceiver.class),
PendingIntent.FLAG_CANCEL_CURRENT));
URL for code
You can start a sticky service and register an alarm manager that will check again and again that is your application is alive if not then it will run it.
You can also make a receiver and register it for <action android:name="android.intent.action.BOOT_COMPLETED" /> then you can start your service from your receiver. I think there should be some broadcast message when OS or kills some service/application.
Just to give you a rough idea I have done this and its working
1) register receiver
Receiver Code:
#Override
public void onReceive(Context context, Intent intent) {
try {
this.mContext = context;
startService(intent.getAction());
uploadOnWifiConnected(intent);
} catch (Exception ex) {
Logger.logException(ex);
Console.showToastDelegate(mContext, R.string.msg_service_starup_failure, Toast.LENGTH_LONG);
}
}
private void startService(final String action) {
if (action.equalsIgnoreCase(ACTION_BOOT)) {
Util.startServiceSpawnProcessSingelton(mContext, mConnection);
} else if (action.equalsIgnoreCase(ACTION_SHUTDOWN)) {
}
}
Service Code:
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Logger.logInfo("Service Started onStartCommand");
return Service.START_STICKY;
}
I prefer doing nothing in onStartCommand because it will get called each time you start service but onCreate is only called 1st time service is started, so I do most of the code in onCreate, that way I don't really care about weather service is already running or not.
according to #RetoMeyer from Google, the solution is to make the app "sticky".
for this, you must establisH START_STICKY in your intent service management.
check this reference from developer android
Yes, Once memory low issue comes android os starts killing application to compensate the required memory. Using services you can achieve this, your service should run parallely with your application but see, some of the cases even your service will be also killed at the same time. After killing if memory is sufficient android os itself try to restart the application not in all the cases. Finally there is no hard and fast rule to re-invoke your application once killed by os in all the cases it depends on os and internal behaviours.
I am working on parental control/adult content filtering application. This app continuously monitors the calls and smses on a child's mobile and logs all the activity onto a server. For this I am starting a service (MyService.java)
on BOOT_COMPLETED and in the onCreate method of the service I register a contentobserver for the callLog and sms uri ( refer to the code snippet below ) .
Now the issue is, Since I want to monitor every outgoing, incoming call s and sms I want the service to be continuously running ( without being stopped/killed) . Moreover this Service is being just used for registering content observers and not doing any other processing(its OnstartCommand method is dummy ) , so android OS kills the service after sometime. How do I ensure that the service runs continuously and keeps the contentobserver object alive ?
public class MyService extends Service {
private CallLogObserver clLogObs = null;
public void onCreate() {
super.onCreate();
try{
clLogObs = new CallLogObserver(this);
this.getContentResolver().registerContentObserver(android.provider.CallLog.Calls.CONTENT_URI, true, clLogObs);
}catch(Exception ex)
{
Log.e("CallLogData", ex.toString());
}
}
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
#Override
public void onDestroy() {
if( clLogObs !=null )
{
this.getContentResolver().unregisterContentObserver(clLogObs);
}
super.onDestroy();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent, flags, startId);
return Service.START_STICKY;
}
#Override
public boolean onUnbind(Intent intent) {
return super.onUnbind(intent);
}
You cannot ensure your service to be running continuously on Android.
For the use-case you mention, it is better to rely on Broadcast receiver like ACTION_NEW_OUTGOING_CALL & SMS_RECEIVED.
If you feel, above supported Broadcast receivers doesn't cover all your use-cases. Use AlaramManager to periodically start your SERVICE and look into CALL_LOGS and SMS table for any change in data and take appropriate action (this may involve check marking the last visited data on CALL_LOGS and SMS table).
you can set the service to run in the foreground . this will give your service a much lower chance of being killed by the OS .
read here for more information .
The content observer get unregistered as soon as your service get killed. So registering once is not an option and your service must be running all the time. to guarantee this you must return START_STICKY from onStartCommand. You can also start the service in foreground.
But what if a new call arrive when the service is killed? To handle this you can store last processed _id in preferences of your app. and each time get all the new call logs with greater id than saved id. You must process the logs on service onCreate as well as on observer onChange.
You cant guarantee it will run continuously, but you can return START_STICKY from onStartCommand which guarantees that Android will re-start your service if it is killed for any reason.