ITT 2014 - Erik Hellmann - Android Programming - Better and Smarter Networking

Android is now the most popular software platform in the world and millions of people use it in their everyday life. One of the largest challenges for application developers is how to make their applications consume as little network and battery as possible. Although the Android platform has improved a lot over the years, there are still lots of things that developers need to think about. In this session, Erik goes through the different choices and what they will mean to your application. Learn about the latest protocols, Android platform tricks and how to get the most out of an Android device without draining its battery.

Transcript

1. Smarter and Better Networking Erik Hellman, Spotify @ErikHellman google.com/+ErikHellman Android Programming
2. Erik Hellman • Engineer @ Ericsson • Lead Architect @ Sony Mobile • Research Engineer @ Sony • Android Developer @ Spotify • Speaking at dev conferences • Wrote a book on Android
3. I wrote a book! :-)
5. Very bad 3G!
6. • Reduce battery consumption! • Reduce data traffic! • Improve UI performance! • Reduce cost of backend services
7. WiFi topology Internet Socket terminates here!
8. Mobile network topology http://en.wikipedia.org/wiki/GPRS_core_network Socket terminates here!
9. Different networks have different behaviour!
11. Network and Battery • Mobile data uses more battery than WiFi • Connections (sockets) linger longer on a mobile network • Battery drains faster if network activity changes frequently
12. Network and Battery • Stay more passive when on mobile network • Always make sure you properly close all your connections! • Try to perform all network operations in a tight sequence and together with other apps (see AlarmManager)
13. Networking Optimisations • Reduce payload size • Better protocol stack • Better networking strategy • Better app design
14. Reduce payload size • JSON • {“name”:"Erik  Hellman","age":37} - 32 bytes • Google Protobuf (hexadecimal) • 0a  0c  45  72  69  6b  20  48  65  6c  6c  6d  61   6e  10  25  - 16 bytes
15. Protobuf in Android dependencies  {          compile  fileTree(dir:  'libs',  include:  ['*.jar'])          compile  'com.android.support:appcompat-­‐v7:19.+'          compile  'com.squareup.wire:wire-­‐runtime:1.4.0'   } build.gradle:
16. Protobuf in Android: Schema package  se.hellsoft.bettersmarternetworking;   ! option  java_package  =  "se.hellsoft.bettersmarternetworking";   ! message  SimpleMessage  {          enum  State  {                    STOPPED  =  1;                  PREPARED  =  2;                  RUNNING  =  3;                  PAUSED  =  4;                  ERROR  =  5;          }   !        required  int32  message_id  =  1;  //  Unique  id  for  each  element          optional  int64  timestamp  =  2;            required  State  server_state  =  3;          optional  string  title  =  4;          required  bytes  content  =  5;  //  A  byte  array   } messages.proto:
17. Protobuf in Android: Generate Java code $ java -jar ../wire-compiler-1.4.0-jar-with-dependencies.jar \
 --java_out=app/src/main/java/ messages.proto Run in console:
18. Protobuf in Android: Java usage public  SimpleMessage  deserializeMessage(byte[]  data)  throws  IOException  {     Wire  wire  =  new  Wire();     return  wire.parseFrom(data,  SimpleMessage.class);   }       public  byte[]  buildAndSerialize(int  msgId,  long  timestamp,                                                                    SimpleMessage.State  state,                                                                    String  title,  byte[]  content)  {     SimpleMessage.Builder  builder  =  new  SimpleMessage.Builder();     SimpleMessage  simpleMessage  =  builder.message_id(msgId)         .timestamp(timestamp).server_state(state)         .title(title).content(ByteString.of(content)).build();     return  simpleMessage.toByteArray();   } Java code using Protobuf:
19. Better protocol stack • Apache HttpClient (AndroidHttpClient) - Avoid! • HttpURLConnection (Default on Android) - Ok… • OkHttp (Third-party. Support SPDY) - Better :)
20. HTTP/1.1 • Old (1999) • Insecure (No default encryption) • Bloated (Only content can be compressed) • Blocking (Only one request at a time per socket)
21. SPDY (and HTTP/2) • Always encrypted • Header compression • Multiplexing requests and responses • Server-side push
22. SPDY Performance http://blog.chromium.org/2013/11/making-web-faster-with-spdy-and-http2.html
23. OkHttp in Android public  void  doOkHttpDemo(URL  url)  throws  IOException  {     OkHttpClient  okHttpClient  =  new  OkHttpClient();     HttpURLConnection  httpURLConnection  =  okHttpClient.open(url);     if(httpURLConnection.getResponseCode()  ==  HttpURLConnection.HTTP_OK)  {       //  TODO  Read  response...     }     httpURLConnection.disconnect();   }   dependencies  {          compile  fileTree(dir:  'libs',  include:  ['*.jar'])          compile  'com.android.support:appcompat-­‐v7:19.+'          compile  'com.squareup.okhttp:okhttp:1.5.4'   }
24. Networking strategy • Server-Side Push (Google Cloud Messaging etc.) • Polling at recurring intervals • Triggered by system event • On-demand
25. Google Cloud Messaging • Eliminates all redundant network calls • Always up to date • Requires Google Play, a Google account and dependencies towards Google Cloud.
26. Polling with AlarmManager • Polling of data at regular intervals • Will generate redundant network calls • No dependency on Google services or accounts
27. Using AlarmManager public  void  doAlarmManagerPolling(Context  context)  {     AlarmManager  alarmManager  =  (AlarmManager)  context         .getSystemService(Context.ALARM_SERVICE);         Intent  syncNetwork  =  new  Intent(NetworkSync.ACTION_SYNC_NETWORK);     syncNetwork.setComponent(new  ComponentName(context,  NetworkSync.class));         PendingIntent  pendingIntent  =  PendingIntent.getService(context,  0,                                    syncNetwork,  0);         alarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME,  0,           AlarmManager.INTERVAL_HALF_HOUR,  pendingIntent);   }  
28. Triggered by events • Activity.onResume() - User started your app • Intent.ACTION_USER_PRESENT - User unlocked device • AlarmManager.setExact() - Trigger at exact time • WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION - Connected to a WiFi (with specifics about SSID)
29. Improving app design • Use the Android components correctly! • Don’t reinvent the wheel! • Design for vanilla Android!
30. Android Components Service Activity BroadcastReceiver ContentProvider Should only be used for UI! Anything long running not related to UI Persisting data Receiving (system) events
31. Very Common App Design public  void  doRefreshNetwork(View  view)  {     new  AsyncTask<URL,  Void,  JSONArray>()  {   !     @Override       protected  JSONArray  doInBackground(URL...  params)  {         try  {           HttpURLConnection  connection  =                 (HttpURLConnection)  params[0].openConnection();           if(connection.getResponseCode()  ==  HttpURLConnection.HTTP_OK)  {             JSONArray  result  =  null;             //  Parse  JSON  response..             return  result;           }         }  catch  (IOException  e)  {           //  TODO  error  handling         }         return  null;       }   !     @Override       protected  void  onPostExecute(JSONArray  jsonArray)  {         super.onPostExecute(jsonArray);         mJsonArrayAdapter.setJSONArray(jsonArray);         mJsonArrayAdapter.notifyDataSetChanged();       }     }.execute(REST_API_URL);   }
32. Better App Design Activity + ListView + Loader Service ContentProvider startService() getContentResolver().insert() HttpUrlConnection getContentResolver().notifyChange(); BroadcastReceiver Network changed!
33. Real-time apps (games) Activity Service bindService() onMessage() Asynchronous communication
34. Additional tips • Use latest tools (Android Studio, Gradle etc.)! • Loading images is tricky - use a library! • Picasso - http://square.github.io/picasso/ • Cancel requests properly (ListView etc.) • Close sockets and connection properly! • Batch network data if possible! • Using paging and caching when possible! • Listen for network and configuration changes!
35. Sum it up… • 3G acts differently than WiFi! • Consider a different data format! • Pick a better protocol stack! • Server push, polling at interval or system event? • Design your app correctly - don’t re-invent the wheel!
37. Useful links ! • https://github.com/square/wire - Protobuf library • http://blog.chromium.org/2013/11/making-web-faster-with-spdy- and-http2.html - Great article about SPDY and HTTP/2 • http://square.github.io/okhttp/ - HTTP client supporting SPDY • http://square.github.io/picasso/ - Powerful image loading library • http://developer.android.com/training/building-connectivity.html - Android documentation on networking • www.wiley.com/go/ptl/androidprogramming - My book :)
38. – Erik Hellman “The best network call is the one you didn’t have to do!”
39. Android Programming Pushing the Limits