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Real-Life Architecture

@mobileLarson @_openKnowledge

Lars Röwekamp | CIO New Technologies

http://www.flickr.com/photos/smb_flickr/522192756/

http://foter.com/

http://creativecommons.org/licenses/by-nc-nd/2.0/

Real-Life Architecture Android 4+

MTC2014

Eigentlich ist ja alles ganz einfach ...


MTC2014

Eigentlich ist ja alles ganz einfach ...


MTC2014

... auch wenn es kompliziert(er) wird.


MTC2014

... auch wenn es kompliziert(er) wird.

Real-Life ArchitectureMTC2014

Splash Overview Share

Preferences

Map


Android 4+


MTC2014


MTC2014

Wo liegt das ...

Problem?

Es war einmal eine App ...Real-Life Architecture

MTC2014

Splash Overview Share

Preferences

Map


MTC2014


MTC2014

Anforderungen easy Version !

‣ klassische Android Anwendung ‣ Kunden CI und White Label ‣ Anbindung von (Web) Services ‣ Vorlieben/Einstellungen merken ‣ Time-to-Market


MTC2014

Anforderungen eXtended Edition !

‣ Smartphone & Tablet Support ‣ Android 2.3 & Android 4.x Support ‣Multi-Language Support ‣Multi-User Support ‣ Localization Support


MTC2014

Anforderungen Directors Cut !

‣ Daten immer aktuell ‣ Daten auch offline ‣ Daten auch für Dritte ‣ batterieschonend ‣ ... und natürlich „Top Security“ ‣ ... und natürlich „Top Usabillity“

... und die hatte eine ArchitekturReal-Life Architecture

MTC2014

... und die hatte eine ArchitekturReal-Life Architecture

MTC2014


MTC2014

Let‘s go !

‣ klein starten ‣ schrittweise erweitern ‣ stets lauffähig und sinnvoll !

‣ Refactoring ist ein Zeichen von Stärke

MTC2014 Real-Life Architecture

Schritt 1: POI senden

Schritt 1: POI sendenReal-Life Architecture

MTC2014

Schritt 1: POI sendenReal-Life Architecture

MTC2014

automatisch vs. manuell

Position / Notiz

MTC2014

POI senden Best Practices !

‣ POI via GPS erfragen ‣ POI via Adresseingabe erfragen !

‣ UI und Logik trennen ‣ Kommunikation in eigene Lib auslagern ‣ „Application not Responding“ vermeiden

Real-Life ArchitectureSchritt 1: POI senden

MTC2014

Code Diving ...


MTC2014

POI senden Pitfalls !

‣ Network on Main Thread ‣ Strict Mode


MTC2014

POI senden Pitfalls !

‣ Network on Main Thread ‣ Strict Mode


MTC2014

Netzwerkzugriff seit 4.x nur via ...

Async


MTC2014

POI senden Async !

‣ Handler & Threads ‣ AsyncTask & „nix“ ‣ IntentService & BroadcastReceiver


MTC2014class PostToFriendFinder extends AsyncTask<Void, Integer, String> { ! // Invoked on the background thread immediately after onPreExecute() // finishes executing. Performs background computation that can take // a long time. The parameters of the async task are passed to this // step. // @Override protected String doInBackground(Void... params) { try { getFriendFinder().sharePointOfInterstVisit(poi, note); return "Sending point of interest visitation was successfull."; } catch (FriendFinderException ex) { return "Sending point of interest visitation failed."; } } @Override protected void onProgressUpdate(Integer... values) { ... } ! @Override protected void onPostExecute(String result) { ... } !}


AsyncTasks

MTC2014class PostToFriendFinder extends AsyncTask<Void, Integer, String> { ! // Invoked on the background thread immediately after onPreExecute() // finishes executing. Performs background computation that can take // a long time. The parameters of the async task are passed to this // step. // @Override protected String doInBackground(Void... params) { try { getFriendFinder().sharePointOfInterstVisit(poi, note); return "Sending point of interest visitation was successfull."; } catch (FriendFinderException ex) { return "Sending point of interest visitation failed."; } } @Override protected void onProgressUpdate(Integer... values) { ... } ! @Override protected void onPostExecute(String result) { ... } !}

Async


POI & Note?

AsyncTasks

MTC2014class PostToFriendFinder extends AsyncTask<Void, Integer, String> { ! private PointOfInterest poi; private String note; public PostToFriendFinder(PointOfInterest poi, String note) { ... } // @Override protected String doInBackground(Void... params) { try { getFriendFinder().sharePointOfInterstVisit(poi, note); return "Sending point of interest visitation was successfull."; } catch (FriendFinderException ex) { return "Sending point of interest visitation failed."; } } @Override protected void onProgressUpdate(Integer... values) { ... } ! @Override protected void onPostExecute(String result) { ... } !}


AsyncTasks

MTC2014// onClick handler to collect input data, create a new Point of Interest // and share it async via related service public void onClick(View view) { float latitude = ...; float longitude = ...; String note = ...; ! // create new point of interest PointOfInterest poi = new PointOfInterest(longitude, latitude, 0.00F); ! // create async tasks to communicate with the cloud service new PostToFriendFinder(poi, note).execute(); !}


AsyncTasks

MTC2014// onClick handler to collect input data, create a new Point of Interest // and share it async via related service public void onClick(View view) { float latitude = ...; float longitude = ...; String note = ...; ! // create new point of interest PointOfInterest poi = new PointOfInterest(longitude, latitude, 0.00F); ! // create async tasks to communicate with the cloud service new PostToFriendFinder(poi, note).execute(); !}


AsyncTasks

MTC2014public class SendService extends IntentService { ... @Override protected void onHandleIntent(Intent intent) { ! // get point of interest and note form intent extras PointOfInterest poi = (PointOfInterest)intent.getSerializableExtra(POINT_OF_INTEREST_EXTRA); String note = intent.getStringExtra(NOTE_EXTRA); // get current friend finder instance (connection to friend finder WS) FriendFinder friendFinder = new FriendFinder(getCurrentContact()); String result; try { // share own position to WS friendFinder.sharePointOfInterstVisit(poi, note); result = "Sending point of interest visitation was successfull."; } catch (FriendFinderException e) { result = "Sending point of interest visitation failed."; } // inform registered receivers via notification LocalBroadcastManager.getInstance(this).sendBroadcast(new Intent(POI_SHARED)); } }


IntentService

MTC2014// onClick handler to collect input data, create an Intent // and share it async via related intent service public void onClick(View view) { float latitude = ...; float longitude = ...; String note = ...; ! // create new point of interest PointOfInterest poi = new PointOfInterest(longitude, latitude, 0.00F); ! Intent serviceIntent = new Intent(this, SendService.class); serviceIntent.putExtra(SendService.POINT_OF_INTEREST_EXTRA, poi); serviceIntent.putExtra(SendService.NOTE_EXTRA, note); startService(serviceIntent); }


IntentService

MTC2014// onClick handler to collect input data, create an Intent // and share it async via related intent service public void onClick(View view) { float latitude = ...; float longitude = ...; String note = ...; ! // create new point of interest PointOfInterest poi = new PointOfInterest(longitude, latitude, 0.00F); ! Intent serviceIntent = new Intent(this, SendService.class); serviceIntent.putExtra(SendService.POINT_OF_INTEREST_EXTRA, poi); serviceIntent.putExtra(SendService.NOTE_EXTRA, note); startService(serviceIntent); }


IntentService


Schritt 2: Einstellungen merken



Schritt 2: Einstellungen merkenMTC2014

Einstellungen merken Best Practices !

‣ Einstellungen zentral verwalten ‣ Einstellungen gruppieren ‣ UI zur Bearbeitung bereit stellen ‣ Settings Design Guide beachten


Schritt 2: Einstellungen merkenMTC2014

Einstellungen merken Best Practices !

‣ Einstellungen zentral verwalten ‣ Einstellungen gruppieren ‣ UI zur Bearbeitung bereit stellen ‣ Settings Design Guide beachten


MTC2014

Einstellungen merken Pitfalls !

‣ Hierarchie von Einstellungen ‣ Einstellungen können sich ändern ‣ Zugriff auf Einstellungen an mehreren Stellen !

‣ Android 2.x vs. Android 4.x

Real-Life ArchitectureSchritt 2: Einstellungen merken

MTC2014

Einstellungen via ...

Preferences


MTC2014<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">  <PreferenceScreen android:key="button_voicemail_category_key" android:title="@string/voicemail" android:persistent="false"> <ListPreference android:key="button_voicemail_provider_key" android:title="@string/voicemail_provider" ... />  <PreferenceScreen android:key="button_voicemail_setting_key" android:title="@string/voicemail_settings" android:persistent="false"> ... </PreferenceScreen> <RingtonePreference android:key="button_voicemail_ringtone_key" android:title="@string/voicemail_ringtone_title" android:ringtoneType="notification" ... /> ... </PreferenceScreen> ... </PreferenceScreen>


http://schemas.android.com/apk/res/android

MTC2014<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">  <PreferenceScreen android:key="button_voicemail_category_key" android:title="@string/voicemail" android:persistent="false"> <ListPreference android:key="button_voicemail_provider_key" android:title="@string/voicemail_provider" ... />  <PreferenceScreen android:key="button_voicemail_setting_key" android:title="@string/voicemail_settings" android:persistent="false"> ... </PreferenceScreen> <RingtonePreference android:key="button_voicemail_ringtone_key" android:title="@string/voicemail_ringtone_title" android:ringtoneType="notification" ... /> ... </PreferenceScreen> ... </PreferenceScreen>


http://schemas.android.com/apk/res/android

MTC2014public static class SettingsFragment extends PreferenceFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ! // Load the preferences from an XML resource addPreferencesFromResource(R.xml.preferences); } ... } !!public class SettingsActivity extends Activity { ! @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ! // Display the fragment as the main content. getFragmentManager().beginTransaction() .replace(android.R.id.content, new SettingsFragment()) .commit(); } }


MTC2014public class FriendFinderApplication extends Application implements OnSharedPreferenceChangeListener { ! SharedPreferences preferences; ... ! @Override public void onCreate() { super.onCreate(); this.preferences = PreferenceManager.getDefaultSharedPreferences(this); ! // recommanded in onResume (register) / onPause (unregister) this.preferences.registerOnSharedPreferenceChangeListener(this); // use preferences to initialize app data ... } ... ! @Override public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) { // force reload of preferences and reinitialization of global data ... } }


Ok, aber wofür brauche ich dann

noch die PreferenceActivity?





MTC2014public class AllPreferenceActivity extends PreferenceActivity { ! // --- load all headers @Override public void onBuildHeaders(List<Header> target) { ! super.onBuildHeaders(target); loadHeadersFromResource(R.xml.pref_header, target); } ! // --- checks if chosen fragment is valid (added in API 19) @Override protected boolean isValidFragment(String fragmentName) { return MapsPreferenceFragment.class.getName().equals(fragmentName) || ServerPreferenceFragment.class.getName().equals(fragmentName) || UserPreferenceFragment.class.getName().equals(fragmentName) || super.isValidFragment(fragmentName); } }


Wie reagiere ich auf Änderungen?

MTC2014public class FriendFinderApplication extends Application implements OnSharedPreferenceChangeListener { ...! @Override public void onSharedPreferenceChanged(SharedPreferences sharedPrefs, String key) {! // user name must not be empty if (Preferences.PREF_USER_NICK_NAME.equals(key)) { // check if changed user name forces restart of updater service // to load new friend list ... }! // update UI with new preference settings ... }


Und wie verhindere ich falsche Eingaben?

MTC2014!@Overridepublic void onSharedPreferenceChanged(SharedPreferences sharedPrefs, String key) {! // user name must not be empty if (Preferences.PREF_USER_NICK_NAME.equals(key)) {! if (sharedPrefs.getString(Preferences.PREF_USER_NICK_NAME,"").equals("")) {! Editor editor = sharedPrefs.edit(); editor.putString(Preferences.PREF_USER_NICK_NAME, DEFAULT_USER_NAME); editor.commit(); return; }! }! // check if changed preferences forces restart of updater service ... }


MTC2014

Code Diving ...



Schritt 3: POIs abgleichen



Schritt 3: POIs abgleichenReal-Life Architecture

MTC2014

MTC2014

POIs abgleichen Best Practices !

‣ POIs regelmäßig abgleichen ‣ POIs so aktuell wie möglich halten ‣ POIs im Hintergrund laden

Real-Life ArchitectureSchritt 3: POIs abgleichen

MTC2014

POIs abgleichen Pitfalls !

‣ regelmäßig ‣ aktuell ‣ im Hintergrund


MTC2014

Hintergrundaufgaben via ...

Service




MTC2014public class UpdaterService extends Service { ! private Updater updater; ... public IBinder onBind(Intent intent) { ... } public void onCreate() { ... } public int onStartCommand(Intent intent, int flags, int startId) { .. } public void onDestroy() { ... } ! private class Updater extends Thread { ! public Updater() { ... } ! public void run() { UpdaterService updaterService = UpdaterService.this; while (updaterService.running) { try { ... // do some work Thread.sleep(DELAY); } catch (InterruptedException ex) { updaterService.running = false; } } ! } } }


MTC2014public class UpdaterService extends Service { ! private Updater updater; ... public IBinder onBind(Intent intent) { ... } public void onCreate() { ... } public int onStartCommand(Intent intent, int flags, int startId) { .. } public void onDestroy() { ... } ! private class Updater extends Thread { ! public Updater() { ... } ! public void run() { UpdaterService updaterService = UpdaterService.this; while (updaterService.running) { try { ... // do some work Thread.sleep(DELAY); } catch (InterruptedException ex) { updaterService.running = false; } } ! } } }

Real-Life Architecture Starten & Stoppen?

Online vs. Offline?


MTC2014public class FriendFinderApplication extends Application { ... /** check is updater service is running with the help of the * <code>RunningServiceInfo</code> of the <code>ActivityManager</code> */ public boolean isUpdaterServiceRunning() { ! String serviceName; ActivityManager manager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE); for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) { serviceName = service.service.getClassName(); ! // is the requested service running? if(UpdaterService.class.getName().equals(serviceName)) { return true; } } return false; } !}


MTC2014

Code Diving ...



Schritt 4: Offline-Modus



Schritt 4: Offline-ModusReal-Life Architecture

MTC2014

MTC2014

Offline Modus Best Practices !

‣ POIs via Online-Modus abgleichen ‣ POIs für Offline-Modus speichern ‣ POI UI aktuell halten !

‣ Datenzugriff kapseln ‣ Datenzugriff optimieren

Real-Life ArchitectureSchritt 4: Offline-Modus

MTC2014

Offline-Modus Pitfalls !

‣ Online vs. Offline ‣ Read vs. Write ‣ UI aktuell halten !

‣ Testen


MTC2014

Daten verfügbar machen via ...

SQL & Adapter



?





PoiVisitations

username, name,

...

Adapter FROM TO

username tx_username

... ...

!

<Row-Layout />

<ListView>

</ListView>

<Row-Layout />

<Row-Layout />

<LinearLayout>

</Linearlayout>

t_timestamp

tx_name

tx_note

res/layout/row.xmlres/layout/mylist.xml

src/MyAdapter.java src/MyDbHelper.java



public class PositionOverviewActivity extends Activity { ! Cursor cursor; ListView listView; PositionOverviewAdapter adapter; FriendFinderData friendFinderData; ! static final String[] FROM = { ... }; static final int[] TO = { ... }; ! public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_position_overview); // lookup list view listView = (ListView) findViewById(R.id.list_position_overview); ! // lookup data friendFinderData = ((FriendFinderApplication) getApplication()) .getFriendFinderData(); } ... }



public class PositionOverviewActivity extends Activity { ! Cursor cursor; ListView listView; PositionOverviewAdapter adapter; FriendFinderData friendFinderData; ! ... ! public void onResume() { super.onResume(); cursor = friendFinderData.getPoiVisitations(); // start managing the cursor startManagingCursor(cursor); // created special adapter adapter = new PositionOverviewAdapter(this, cursor); listView.setAdapter(adapter); } ... }



public class PositionOverviewActivity extends Activity { ! Cursor cursor; ListView listView; PositionOverviewAdapter adapter; FriendFinderData friendFinderData; ! ... ! public void onResume() { super.onResume(); cursor = friendFinderData.getPoiVisitations(); // deprecated in Android 4.x startManagingCursor(cursor); // created special adapter adapter = new PositionOverviewAdapter(this, cursor); listView.setAdapter(adapter); } ... }








MTC2014

Das kleine Loader 1x1 !

‣ asynchrones Laden von Daten ‣ verfügbar in Activities und Fragments ‣ Content-Change-Monitoring der Datensource ‣ Reconnection zu vorheriger Position !

‣ CursorLoader (für ContentProvider) ‣ Loader oder AsyncTaskLoader


MTC2014// Activity implementing Loader Callbacks public class MyActivity extends Activity implements LoaderManager.LoaderCallback<Cursor> { ! @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ... adapter = new SimpleCursorAdapter(...) setListAdapter(adapter) getLoaderManager().initLoader(0, null, this); } ... !}


MTC2014// Activity implementing Loader Callbacks public class MyActivity extends Activity implements LoaderManager.LoaderCallback<Cursor> { ! ... // loader was created and is ready to work public Loader<Cursor> onCreateLoader(int id, Bundle args){ // set content provider query URI etc. ... // access content provider return new CursorLoader(this, cpQueryUri, projection, where, whereArgs, sortOrder); } ... }


MTC2014// Activity implementing Loader Callbacks public class MyActivity extends Activity implements LoaderManager.LoaderCallback<Cursor> { ! ... // loader finished loading - data is available public void onLoadFinished(Loader<Cursor> l, Cursor c){ adapter.swapCursor(c); } ! // loader was reseted - its data is unavailable public void onLoaderReset(Loader<Cursor> l){ adapter.swapCursor(null); } }


MTC2014

Loader und ... !

‣ Content Provider für Lau ‣ SQLite via eigenem AsyncTaskLoader<Cursor>


MTC2014

Und wie kann ich die DB Daten sehen ... !

‣ DB liegt unter

/data/data/[mypackage]/databases/[myapp].db !

‣ DB Copy auf den Rechner ‣ SQLiteManager PlugIn für Eclipse


MTC2014

Code Diving ...



Schritt 5: Mobile Intelligenz



Schritt 5: Mobile IntelligenzReal-Life Architecture

MTC2014

MTC2014

Mobile Intelligenz Best Practices !

‣ POIs nur senden/abfragen, wenn Internet ‣ POIs nur senden/abfragen, wenn Strom ‣ UI aktualisieren, wenn neue Daten ‣ ...

Real-Life ArchitectureSchritt 5: Mobile Intelligenz

MTC2014

Mobile Intelligenz Pitfalls !

‣ POIs im günstigsten Moment abfragen ‣ Umgebungsänderungen feststellen ‣ Zugriffe ausreichend absichern


MTC2014

Mobile Intelligenz via ...

Broadcast Receiver


MTC2014

Was sind Broadcast Receiver? !

‣ Publisher-Subscriber-Pattern ‣ Observer-Pattern !

‣ App / System sendet Nachricht ‣ Broadcast Receiver hört auf Nachricht




MTC2014

Was helfen uns die Broadcast Receiver? !

‣ Service starten sobald Device gebootet ist !

‣ auf Internet-Verfügbarkeit reagieren ‣ auf Batteriestatus reagieren !

‣ auf neue POIs reagieren



public class BootReceiver extends BroadcastReceiver { private static final String TAG = BootReceiver.class.getSimpleName(); ! // start update service after system start automatically @Override public void onReceive(Context context, Intent intent) { context.startService(new Intent(context, UpdaterService.class)); Log.d(TAG, "onReceived"); } }

‣ Service starten sobald Devices gebootet ist



 !... !<receiver android:name=".BootReceiver" > <intent-filter> <action android:name="android.intent.action.BOOT_COMPLETED" /> </intent-filter> </receiver> !<uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" /> !...



public class NetworkReceiver extends BroadcastReceiver { public void onReceive(Context context, Intent intent) { // check if network is available boolean isNetworkDown = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false); if (isNetworkDown) { context.stopService(new Intent(context, UpdaterService.class)); } else { context.startService(new Intent(context, UpdaterService.class)); } } }

‣ auf Internet-Verfügbarkeit reagieren



 !... !<receiver android:name=".NetworkReceiver" > <intent-filter> <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> </intent-filter> </receiver> !<uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> !...



public class PositionOverviewActivity extends Activity { ... ! class NewLocationReceiver extends BroadcastReceiver { public void onReceive(Context context, Intent intent) { LoaderManager lm = getLoaderManager(); lm.restartLoader(0, null, PositionOverviewActivity.this); } } }




public class PositionOverviewActivity extends Activity { ... ! @Override public void onResume() { super.onResume(); getActivity().registerReceiver(newLocationReceiver, new IntentFilter(UpdaterService.NEW_LOCATION_INTENT)); } ! @Override public void onPause() { super.onPause(); getActivity().unregisterReceiver(newLocationReceiver); } }



MTC2014

Code Diving ...



Schritt 6: Externer Datenzugriff



Schritt 6: Externer DatenzugriffReal-Life Architecture

MTC2014

MTC2014

Externer Datenzugriff Best Practices !

‣ Content Provider zur Datenbereitstellung ‣Widget / App zur Datennutzung

Real-Life ArchitectureSchritt 6: Externer Datenzugriff

MTC2014

Externer Datenzugriff Pitfalls !

‣ Lesen vs. Schreiben ‣ Security Defaults ‣ Android 2.x vs. Android 4.x


MTC2014

Daten verfügbar machen via ...

Content Provider





 !... ! <provider android:name =".PositionProvider" android:authorities ="de.openknowledge.mtc.ff.poi" /> !...



 !... ! <provider android:name =".PositionProvider" android:authorities ="de.openknowledge.mtc.ff.poi" /> !...

Öffentlich?

Lesen vs. Schreiben?



 !... ! <provider android:name =".PositionProvider" android:authorities ="de.openknowledge.mtc.ff.poi" android:exported ="true" android:readPermission ="de.openknowledge.mtc.ff.poi.READ_DATA" /> ...


MTC2014

Code Diving ...



Schritt 7: Standorte anzeigen


Schritt 7: Standorte anzeigen

MTC2014

Standorte anzeigen Best Practices !

‣ Interaktive Karte ‣ eigenen Standort hervorheben ‣ Detailinfos beim „Anklicken“ ‣ User Controlls

Real-Life ArchitectureSchritt 7: Standorte anzeigen

MTC2014

Standorte anzeigen Pitfalls !

‣ Google Maps v2 ‣ Google Play Service ‣ Emulator


MTC2014

Standorte anzeigen via ...

Google Maps API v2



Schritt 7: Google Maps API v2

MTC2014

Google Maps v2 Pitfalls !

‣ API laden via Google Play Service ‣ Google Maps API Key generieren ‣Manifest.xml anpassen ‣Map Fragment „bauen“ ‣Map Activity implementieren

Schritt 7: Google Maps API v2Real-Life Architecture

MTC2014


‣ API laden via Google Play Service ‣ Google Maps API Key generieren ‣Manifest.xml anpassen ‣Map Fragment „bauen“ ‣Map Activity implementieren ‣ ... sie sehen, sie sehen nix (im Emulator)


MTC2014


‣ API laden via Google Play Service ‣ Google Maps API Key generieren ‣Manifest.xml anpassen ‣Map Fragment „bauen“ ‣Map Activity implementieren ‣ ... sie sehen, sie sehen nix (im Emulator)


adb -e install com.google.android.gms.apk

adb -e install com.android.vending.apk

MTC2014

Code Diving ...


Pho

to c

redi

t: S

antiM

B .

/ Fot

er.c

om /

CC

BY-

NC

-ND

@mobileLarson @_openKnowledge

Lars Röwekamp | CIO New Technologies


http://www.flickr.com/photos/smb_flickr/522192756/

http://foter.com/

http://creativecommons.org/licenses/by-nc-nd/2.0/