Android Cloud to Device Messaging Framework at GTUG Stockholm
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The document discusses the Android Cloud to Device Messaging (C2DM) framework. It allows application servers to send lightweight messages to Android apps. Key points: - C2DM notifies apps of new data to fetch rather than sending large amounts of content. It makes no guarantees about message delivery or order. - Apps can receive messages even when not running by using intent broadcasts. C2DM only passes raw message data. - Apps must register with C2DM to receive messages and can unregister. Registration requires Android 2.2+ with the Market app installed. - The app server sends messages via HTTP using a registration ID and authorization token. C2DM handles storing and delivering messages when
Android Cloud to Device Messaging Framework at GTUG Stockholm
- 1. Android Cloud to Device Messaging Framework
- 3. "It allows third-party application servers to send lightweight messages to their Android applications" Not designed to send a lot of content via messages. Instead use C2DM to tell the application that there is new data on the server to fetch.
- 4. "C2DM makes no guarantees about delivery or the order of messages" Eg. not suitable for instant messaging, instead use C2DM to notify the user that there is new messages.
- 5. "An application on an Android device doesn’t need to be running to receive messages" Intent broadcast wake up the app
- 6. "It does not provide any built-in user interface or other handling for message data" Passes raw message data. You are free to do whatever you want with the data. Fire a notification, send SMS, start another application etc.
- 7. "It requires devices running Android 2.2 or higher that also have the Market application installed" Market is needed for technical reasons. No need to distribute via Market.
- 8. "It uses an existing connection for Google services" Requires the user to be logged in with a Google Account on the device.
- 9. Establish connection with conn servers Send to conn Send to servers device Stores message App server sends HTTP POST Google http://code.google.com/events/io/2010/sessions/push-applications-android.html
- 10. Lifecycle Register device App server send message Device receives message Unregister device
- 11. Register device App fires off Intent to register with Google com.google.android.c2dm.intent.REGISTER App receives Intent with registration ID from Google com.google.android.c2dm.intent.REGISTRATION App sends registration ID to app server
- 12. Register device // Intent to register Intent regIntent = new Intent("com.google.android.c2dm.intent.REGISTER"); // Identifies the app regIntent.putExtra("app", PendingIntent.getBroadcast(context, 0, new Intent(), 0)); // Identifies the role account, same as used when sending regIntent.putExtra("sender", senderEmail); // Start registration process context.startService(regIntent);
- 13. Register device public void onReceive(Context context, Intent intent) { if (intent.getAction().equals("...REGISTRATION")) { handleRegistration(context, intent); } } private void handleRegistration(Context context, Intent intent) { String registration = intent.getStringExtra("registration_id"); if (intent.getStringExtra("error") != null) { // Registration failed, should try again later. } else if (intent.getStringExtra("unregistered") != null) { // unregistration done } else if (registration != null) { // Send the registration ID to app server // This should be done in a separate thread. // When done, remember that all registration is done. } }
- 14. Unregister device App fires off a unregister Intent to register with Google com. google.android.c2dm.intent.UNREGISTER App tells app server to remove the stored registration ID
- 15. <manifest ... <application ... <service android:name=".C2DMReceiver" /> <receiver android:name="com.google.android.c2dm.C2DMBroadcastReceiv <intent-filter> <action android:name="com.google.android.c2dm.intent.RECEIVE" / <category android:name="com.markupartist.sthlmtraveling" /> </intent-filter> <intent-filter> <action android:name="com.google.android.c2dm.intent.REGISTRATI <category android:name="com.markupartist.sthlmtraveling" /> </intent-filter> </receiver> </application> <uses-sdk android:minSdkVersion="3" android:targetSdkVersion="8" /> <permission android:name="com.markupartist.sthlmtraveling.permission. android:protectionLevel="signature" /> <uses-permission android:name="com.markupartist.sthlmtraveling.permis C2D_MESSAGE" /> <uses-permission android:name="com.google.android.c2dm.permission.REC <uses-permission android:name="android.permission.INTERNET" /> </manifest>
- 16. <manifest ... <application ... <service android:name=".C2DMReceiver" /> <receiver android:name="com.google.android.c2dm.C2DMBroadcastReceive <intent-filter> <action android:name="com.google.android.c2dm.intent.RECEIVE" /> <category android:name=" com.markupartist.sthlmtraveling " /> </intent-filter> <intent-filter> <action android:name="com.google.android.c2dm.intent.REGISTRATIO <category android:name=" com.markupartist.sthlmtraveling " /> </intent-filter> </receiver> </application> <uses-sdk android:minSdkVersion="3" android:targetSdkVersion="8" /> <permission android:name=" com.markupartist.sthlmtraveling .permission. android:protectionLevel="signature" /> <uses-permission android:name=" com.markupartist.sthlmtraveling .permis C2D_MESSAGE" /> <uses-permission android:name="com.google.android.c2dm.permission.RECE <uses-permission android:name="android.permission.INTERNET" /> </manifest>
- 17. Send message From the documentation: For an application server to send a message, the following things must be in place: The application has a registration ID that allows it to receive messages for a particular device. The third-party application server has stored the registration ID. There is one more thing that needs to be in place for the application server to send messages: a ClientLogin authorization token. This is something that the developer must have already set up on the application server for the application (for more discussion, see Role of the Third-Party Application Server). Now it will get used to send messages to the device. http://code.google.com/android/c2dm/index.html#lifecycle
- 18. Send message Retrieve ac2dm auth token (put on app server) Send authenticated POST - GoogleLogin auth=<TOKEN> - URL Encoded parameters registration_id collapse_key deplay_while_idle - optional data.<KEY> - optional Using cURL to interact with Google Data services: http://code.google.com/apis/gdata/articles/using_cURL.html
- 19. ac2dm authorization token curl https://www.google.com/accounts/ClientLogin -d Email=<ACCOUNT_EMAIL> -d Passwd=<PASSWORD> -d accountType=HOSTED_OR_GOOGLE -d source=markupartist-sthlmtraveling-1 -d service=ac2dm SID=DQAAA... LSID=DQAAA... Auth=DQAAA...
- 20. Token can change URL url = new URL(serverConfig.getC2DMUrl()); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); ... // Check for updated token header String updatedAuthToken = conn.getHeaderField("Update-Client-Auth"); if (updatedAuthToken != null && !authToken.equals(updatedAuthToken)) { serverConfig.updateToken(updatedAuthToken); }
- 21. Send message curl https://android.apis.google.com/c2dm/send -d registration_id=<REGISTRATION ID> -d collapse_key=foo -d data.key1=bar -d delay_while_idle=1 -H "Authorization: GoogleLogin auth=<AUTH TOKEN>" Response codes 200 OK - id=<MESSAGE ID> of sent message, success - Error=<ERROR CODE>, failed to send 401 Not Authorized 503 Service Unavailable, retry
- 22. collapse_key Only the latest message with the same key will be delivered Avoids multiple messages of the same type to be delivered to an offline device State should be in app server and not in the message Eg. could be the URL to fetch data from
- 23. delay_while_idle Message is not immediately sent to the device if it is idle
- 24. Receive a message Device receives the message and converts it to Intent - com.google.android.c2dm.intent.RECEIVE App wakes up to handle Intent - data.<KEY> is translated to extras curl https://android.apis.google.com/c2dm/send ... -d data.key1=bar ... protected void onReceive(Context context, Intent intent) { if (intent.getAction().equals("...RECEIVE")) { String key1 = intent.getExtras().getString("key1"); // If starting another intent here remember to set the // flag FLAG_ACTIVITY_NEW_TASK } }
- 25. Chrome to phone http://code.google. com/p/chrometophone/source/browse/#svn/trunk/android/c2dm /com/google/android/c2dm C2DMessaging.register(context, "Role account email"); C2DMessaging.unregister(context);
- 26. public class C2DMReceiver extends C2DMBaseReceiver { public C2DMReceiver() { super("Role account email"); } @Override public void onRegistrered(Context context, String registration) { // Handle registrations } @Override public void onUnregistered(Context context) { // Handle unregistered } @Override public void onError(Context context, String errorId) { // Handle errors } @Override public void onMessage(Context context, Intent intent) { // Handle received message. } }
- 27. Problems Can't send message to device if logged in with the role account
- 28. References http://code.google.com/android/c2dm/ http://code.google.com/events/io/2010/sessions/push- applications-android.html http://code.google.com/p/chrometophone/