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service interview questions

Top 15 service interview questions

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How to automatically start your service after install?

How do you automatically start a service after running an install from a Visual Studio Setup Project?

I just figured this one out and thought I would share the answer for the general good. Answer to follow. I am open to other and better ways of doing this.


Source: (StackOverflow)

How to check if Location Services are enabled?

I'm developing an app on Android OS. I don't know how to check if Location Services are enabled or not.

I need a method that returns "true" if they are enabled and "false" if not (so in the last case I can show a dialog to enable them).


Source: (StackOverflow)

Trying to start a service on boot on Android

I've been trying to start a service when a device boots up on android, but I cannot get it to work. I've looked at a number of links online but none of the code works. Am I forgetting something?

AndroidManifest.xml

<receiver
    android:name=".StartServiceAtBootReceiver"
    android:enabled="true"
    android:exported="false"
    android:label="StartServiceAtBootReceiver" >
    <intent-filter>
        <action android:name="android.intent.action._BOOT_COMPLETED" />
    </intent-filter>
</receiver>

<service
    android:name="com.test.RunService"
    android:enabled="true" />

BroadcastReceiver

public void onReceive(Context context, Intent intent) {
    if ("android.intent.action.BOOT_COMPLETED".equals(intent.getAction())) {
        Intent serviceLauncher = new Intent(context, RunService.class);
        context.startService(serviceLauncher);
        Log.v("TEST", "Service loaded at start");
    }
}

Thanks


Source: (StackOverflow)

How do I update the notification text for a foreground service in Android?

I have a foreground service setup in Android. I would like to update the notification text. I am creating the service as shown below.

How can I update the notification text that is setup within this foreground service? What is the best practise for updating the notification? Any sample code would be appreciated.

public class NotificationService extends Service {

    private static final int ONGOING_NOTIFICATION = 1;

    private Notification notification;

    @Override
    public void onCreate() {
        super.onCreate();

        this.notification = new Notification(R.drawable.statusbar, getText(R.string.app_name), System.currentTimeMillis());
        Intent notificationIntent = new Intent(this, AbList.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
        this.notification.setLatestEventInfo(this, getText(R.string.app_name), "Update This Text", pendingIntent);

        startForeground(ONGOING_NOTIFICATION, this.notification);

    }

I am creating the service in my main activity as shown below:

    // Start Notification Service
    Intent serviceIntent = new Intent(this, NotificationService.class);
    startService(serviceIntent);

Source: (StackOverflow)

How to record video from background of application : Android

I am developing an application which will be able to record video from background of application by using Service.

Problem description :

In my application recording will be scheduled. If user want to record video from 1 PM to 3 PM, he will schedule the task and can exit from application. Application will automatically start recording at 1PM to 3PM.

What I did yet :

I googled about my query but didn't get solution. Many articles say that it is not possible. But in Google Play there are some applications (for eg MyCar Recorder) which can record video from background of application.

I got an article about same but its not working.

What is the way to implement this functionality?


Source: (StackOverflow)

android app with service only

I am creating a application whose only component is a service which keeps on running in background (basically a proxy server) but I am not able to find a way how to start that service. Application can not have any UI or user interaction so I am not using Activity. Broadcast receiver can listen to BOOT broadcast but how do I start service first time when it is installed and how can I keep it running? or is there a broadcast which I can listen after app is installed e.g. may be TIME_TICK but that has to be registered from activity i think


Source: (StackOverflow)

Convert Angular HTTP.get function to a service

I'm trying to convert an Angular HTTP.get function in my controllers.js to a service in services.js.

The examples I have found all have conflicting ways to implement the service and their choice of names is confusing. Furthermore, the actual angular documentation for services uses yet a different syntax than all the examples. I know this is super simple, but please help me out here.

I have app.js, controllers.js, services.js, filters.js.

app.js

angular.module('MyApp', []).
    config(['$routeProvider', function($routeProvider)
        {
            $routeProvider.
                when('/bookslist', {templateUrl: 'partials/bookslist.html', controller:             BooksListCtrl}).
                otherwise({redirectTo: '/bookslist'});
        }
    ]);

controllers.js

function BooksListCtrl($scope,$http) {
    $http.get('books.php?action=query').success(function(data) {
        $scope.books = data;
    });

    $scope.orderProp = 'author';
}

Source: (StackOverflow)

Run a Java Application as a Service on Linux

I have written a Java server application that runs on a standard virtual hosted Linux solution. The application runs all the time listening for socket connections and creating new handlers for them. It is a server side implementation to a client-server application.

The way I start it is by including it in the start up rc.local script of the server. However once started I do not know how to access it to stop it and if I want to install an update, so I have to restart the server in order to restart the application.

On a windows PC, for this type of application I might create a windows service and then I can stop and start it as I want. Is there anything like that on a Linux box so that if I start this application I can stop it and restart it without doing a complete restart of the server.

My application is called WebServer.exe. It is started on server startup by including it in my rc.local as such:

java -jar /var/www/vhosts/myweb.com/phpserv/WebServer.jar &

I am a bit of a noob at Linux so any example would be appreciated with any posts. However I do have SSH, and full FTP access to the box to install any updates as well as access to a Plesk panel.


Source: (StackOverflow)

Python script as linux service/daemon

Hallo,

I'm trying to let a python script run as service (daemon) on (ubuntu) linux.

On the web there exist several solutions like:

http://pypi.python.org/pypi/python-daemon/

A well-behaved Unix daemon process is tricky to get right, but the required steps are much the same for every daemon program. A DaemonContext instance holds the behaviour and configured process environment for the program; use the instance as a context manager to enter a daemon state.

http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/

However as I want to integrate my python script specifically with ubuntu linux my solution is a combination with an init.d script

#!/bin/bash

WORK_DIR="/var/lib/foo"
DAEMON="/usr/bin/python"
ARGS="/opt/foo/linux_service.py"
PIDFILE="/var/run/foo.pid"
USER="foo"

case "$1" in
  start)
    echo "Starting server"
    mkdir -p "$WORK_DIR"
    /sbin/start-stop-daemon --start --pidfile $PIDFILE \
        --user $USER --group $USER \
        -b --make-pidfile \
        --chuid $USER \
        --exec $DAEMON $ARGS
    ;;
  stop)
    echo "Stopping server"
    /sbin/start-stop-daemon --stop --pidfile $PIDFILE --verbose
    ;;
  *)
    echo "Usage: /etc/init.d/$USER {start|stop}"
    exit 1
    ;;
esac

exit 0

and in python:

import signal
import time
import multiprocessing

stop_event = multiprocessing.Event()

def stop(signum, frame):
    stop_event.set()

signal.signal(signal.SIGTERM, stop)

if __name__ == '__main__':
    while not stop_event.is_set():
        time.sleep(3)

My question now is if this approach is correct. Do I have to handle any additional signals? Will it be a "well-behaved Unix daemon process"?


Source: (StackOverflow)

Non-Singleton Services in Angular

Angular clearly states in its documentation that Services are Singletons:

Angular services are singletons

Counterintuitively, module.factory also returns a Singleton instance.

Given that there are plenty of use-cases for non-singleton services, what is the best way to implement the factory method to return instances of a Service, so that each time an ExampleService dependency is declared, it is satisfied by a different instance of ExampleService?


Source: (StackOverflow)

Start service in Android

I want to call a service when a certain activity starts. So, here's the Service class:

public class UpdaterServiceManager extends Service {

    private final int UPDATE_INTERVAL = 60 * 1000;
    private Timer timer = new Timer();
    private static final int NOTIFICATION_EX = 1;
    private NotificationManager notificationManager;

    public UpdaterServiceManager() {}

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void onCreate() {
        // Code to execute when the service is first created
    }

    @Override
    public void onDestroy() {
        if (timer != null) {
            timer.cancel();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startid) {
        notificationManager = (NotificationManager) 
                getSystemService(Context.NOTIFICATION_SERVICE);
        int icon = android.R.drawable.stat_notify_sync;
        CharSequence tickerText = "Hello";
        long when = System.currentTimeMillis();
        Notification notification = new Notification(icon, tickerText, when);
        Context context = getApplicationContext();
        CharSequence contentTitle = "My notification";
        CharSequence contentText = "Hello World!";
        Intent notificationIntent = new Intent(this, Main.class);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                notificationIntent, 0);
        notification.setLatestEventInfo(context, contentTitle, contentText,
                contentIntent);
        notificationManager.notify(NOTIFICATION_EX, notification);
        Toast.makeText(this, "Started!", Toast.LENGTH_LONG);
        timer.scheduleAtFixedRate(new TimerTask() {

            @Override
            public void run() {
                // Check if there are updates here and notify if true
            }
        }, 0, UPDATE_INTERVAL);
        return START_STICKY;
    }

    private void stopService() {
        if (timer != null) timer.cancel();
    }
}

And here is how I call it:

Intent serviceIntent = new Intent();
serviceIntent.setAction("cidadaos.cidade.data.UpdaterServiceManager");
startService(serviceIntent);

The problem is that nothing happens. The above code block is called at the end of the activity's onCreate. I already debugged and no exception is thrown.

Any idea?


Source: (StackOverflow)

Accessing UI thread handler from a service

I am trying some thing new on Android for which I need to access the handler of the UI thread.

I know the following:

  1. The UI thread has its own handler and looper
  2. Any message will be put into the message queue of the UI thread
  3. The looper picks up the event and passed it to the handler
  4. The handler handles the message and sends the specfic event to the UI

I want to have my service which has to get the UI thread handler and put a message into this handler. So that this message will be processed and will be issued to the UI. Here the service will be a normal service which will be started by some application.

I would like to know if this is possible. If so please suggest some code snippets, so that I can try it.

Regards Girish


Source: (StackOverflow)

Unable to start Service Intent

I have a service class. I have exported this class to jar and I have embed the jar in my client app.

When needed, I call the service class. When I try to do this, I get the following error:

Unable to start service Intent {comp={com.sample.service/com.sample.service.serviceClass}} : not found

I have other class apart from the service class, which I am able to access (create object of that class) which are inside the same jar.

I feel I have missed out some thing in my configuration or manifest or so.

Please help me identifying the same. My code is below:

public void onCreate(Bundle savedInstanceState) {    
      super.onCreate(savedInstanceState);  
      Intent intent = new Intent () ;  
      intent.setClassName("com.sample.service" ,"com.sample.service.serviceClass") ;  
      this.startService(intent) ; // when I call this line I get the message...  
      // binding other process continue  here   
}

Client manifest.xml

<service android:name="com.sample.service.serviceClass"  
            android:exported="true" android:label="@string/app_name" 
            android:process=":remote">
   <intent-filter><action android:name="com.sample.service.serviceClass"></action>
   </intent-filter>
</service>

Thanks in advance,
Vinay


Source: (StackOverflow)

Install Windows Service created in Visual Studio

When I create a new Windows Service in Visual Studio 2010, I get the message stating to use InstallUtil and net start to run the service.

I have tried the following steps:

  1. Create new project File -> New -> Project -> Windows Service
  2. Project Name: TestService
  3. Build project as is (Service1 constructor, OnStart, OnStop)
  4. Open command prompt, run "C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe" TestService.exe
  5. Run net start TestService.

Output of step 4

Running a transacted installation.

Beginning the Install phase of the installation.

See the contents of the log file for the C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\TestService\obj\x86\Debug\TestService.exe assembly's progress.

The file is located at C:\Users\myusername\Documents\Visual Studio 2010\Projects\Tes tService\TestService\obj\x86\Debug\TestService.InstallLog.

Installing assembly 'C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestS ervice\TestService\obj\x86\Debug\TestService.exe'.

Affected parameters are:

logtoconsole =

logfile = C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\T estService\obj\x86\Debug\TestService.InstallLog

assemblypath = C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestServ ice\TestService\obj\x86\Debug\TestService.exe

No public installers with the RunInstallerAttribute.Yes attribute could be found in the C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\TestSe rvice\obj\x86\Debug\TestService.exe assembly.

The Install phase completed successfully, and the Commit phase is beginning.

See the contents of the log file for the C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\TestService\obj\x86\Debug\TestService.exe assembly's progress.

The file is located at C:\Users\myusername\Documents\Visual Studio 2010\Projects\Tes tService\TestService\obj\x86\Debug\TestService.InstallLog.

Committing assembly 'C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestS ervice\TestService\obj\x86\Debug\TestService.exe'.

Affected parameters are:

logtoconsole =

logfile = C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\T estService\obj\x86\Debug\TestService.InstallLog

assemblypath = C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestServ ice\TestService\obj\x86\Debug\TestService.exe

No public installers with the RunInstallerAttribute.Yes attribute could be found in the C:\Users\myusername\Documents\Visual Studio 2010\Projects\TestService\TestSe rvice\obj\x86\Debug\TestService.exe assembly.

Remove InstallState file because there are no installers.

The Commit phase completed successfully.

The transacted install has completed.

Output of step 5

The service name is invalid.

More help is available by typing NET HELPMSG 2185.


Source: (StackOverflow)

What is the correct way to start a mongod service on linux / OS X?

I've installed mongodb and have been able to run it, work with it, do simple DB read / write type stuff. Now I'm trying to set up my Mac to run mongod as a service.

I get "Command not found" in response to:

 init mongod start

In response to:

~: service mongod start
service: This command still works, but it is deprecated. Please use launchctl(8) instead.
service: failed to start the 'mongod' service

And if I try:

~: launchctl start mongod
launchctl start error: No such process

So obviously I'm blundering around a bit. Next step seems to be typing in random characters until something works. The command which does work is: mongod --quiet & I'm not sure, maybe that is the way you're supposed to do it? Maybe I should just take off 'quiet mode' and add > /logs/mongo.log to the end of the command line?

I'm building a development environment on a Mac with the intention of doing the same thing on a linux server. I'm just not sure of the Bash commands. All the other searches I do with trying to pull up the answer give me advice for windows machines.

Perhaps someone knows the linux version of the commands?

Thanks very much


Source: (StackOverflow)