View
2.937
Download
2
Category
Tags:
Preview:
DESCRIPTION
foss-sthlm #4 meeting, 26 October.
Citation preview
Android Cloud to Device
Messaging Framework
How to keep data fresh?
PollingSimple to implementAsk for data periodicallyRadio draws a lot of power
PushingHarder to implementLess battery consumption
Only uses network when neededConstant connection
ComponentsIntent
Description of an action to performBroadcastReceiver
Recieve intentsIntentService
Handles asynchronous request, started when neededWakeLock
Wake up the device at desired levelAlarmManager
Schedule the app to run in the futureSynchronize polls with INTERVAL_*
Some interesting projectsCouchOne Mobile for Androidhttp://www.couch.io/android
Ericsson Labs - Mobile Pushhttps://labs.ericsson.com/apis/mobile-push/
Whoopingkof - Evented Socketshttp://github.com/voltron/whoopingkof/
"It allows third-party application servers to send lightweight messages to their Android applications"
"C2DM makes no guarantees about delivery or the order of messages"
"An application on an Android device doesn’t need to be running to receive messages"
"It does not provide any built-in user interface or other handling for message data"
"It requires devices running Android 2.2 or higher that also have the Market application installed"
"It uses an existing connection for Google services"
http://code.google.com/events/io/2010/sessions/push-applications-android.html
Lifecycle
Register deviceApp server send messageDevice receives messageUnregister device
Register deviceApp fires off Intent to register with Googlecom.google.android.c2dm.intent.REGISTER App receives Intent with registration ID from Googlecom.google.android.c2dm.intent.REGISTRATIONApp sends registration ID to app server
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 sendingregIntent.putExtra("sender", senderEmail); // Start registration process context.startService(regIntent);
Register devicepublic 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. }}
Unregister device
App fires off a unregister Intent to register with Google com.google.android.c2dm.intent.UNREGISTERApp tells app server to remove the stored registration ID
<manifest ... <application ... <service android:name=".C2DMReceiver" /> <receiver android:name="com.google.android.c2dm.C2DMBroadcastReceiver"> <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.REGISTRATION" /> <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.C2D_MESSAGE" android:protectionLevel="signature" /> <uses-permission android:name="com.markupartist.sthlmtraveling.permission.C2D_MESSAGE" /> <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" /> <uses-permission android:name="android.permission.INTERNET" /></manifest>
<manifest ... <application ... <service android:name=".C2DMReceiver" /> <receiver android:name="com.google.android.c2dm.C2DMBroadcastReceiver"> <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.REGISTRATION" /> <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.C2D_MESSAGE" android:protectionLevel="signature" /> <uses-permission android:name=" com.markupartist.sthlmtraveling .permission.C2D_MESSAGE" /> <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" /> <uses-permission android:name="android.permission.INTERNET" /></manifest>
Send Message
Send messageFor 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.
http://code.google.com/android/c2dm/index.html#lifecycle
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.
From the documentation:
Send messageRetrieve ac2dm auth token (put on app server)Send authenticated POST - GoogleLogin auth=<TOKEN>- URL Encoded parameters
registration_idcollapse_keydelay_while_idle - optionaldata.<KEY> - optional
Using cURL to interact with Google Data services:
http://code.google.com/apis/gdata/articles/using_cURL.html
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
ac2dm authorization token
SID=DQAAA...LSID=DQAAA...Auth=DQAAA...
Service name for
C2DMAuthorizatio
n token
Token can changeURL url = new URL(serverConfig.getC2DMUrl()); HttpURLConnection conn = (HttpURLConnection) url.openConnection();...// Check for updated token headerString updatedAuthToken = conn.getHeaderField("Update-Client-Auth");if (updatedAuthToken != null && !authToken.equals(updatedAuthToken)) { serverConfig.updateToken(updatedAuthToken);}
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>"
Send message
Response codes200 OK- id=<MESSAGE ID> of sent message, success- Error=<ERROR CODE>, failed to send401 Not Authorized503 Service Unavailable, retry
collapse_keyOnly the latest message with the same key will be deliveredAvoids multiple messages of the same type to be delivered to an offline device State should be in app server and not in the messageEg. could be the URL to fetch data from
delay_while_idleMessage is not immediately sent to the device if it is idle
Receive a message
Receive a message
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 }}
Device receives the message and converts it to Intent - com.google.android.c2dm.intent.RECEIVEApp wakes up to handle Intent- data.<KEY> is translated to extras
Chrome to phonehttp://code.google.com/p/chrometophone/source/browse/#svn/trunk/android/c2dm/com/google/android/c2dmC2DMessaging.register(context, "Role account email");
C2DMessaging.unregister(context);
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. }}
ProblemsCan't send message to device if logged in with the role account 401
References
http://code.google.com/android/c2dm/ http://code.google.com/events/io/2010/sessions/push-applications-android.htmlhttp://code.google.com/p/chrometophone/
Recommended