Overview about Androids Cloud to Device Messaging (C2DM) and a short inside of the Google App Engine.

1. Cloud to Device Messaging(with Google App Engine) Lars Vogel Twitter: @vogella http://www.vogella.de

2. About me – Lars Vogel Works as independent Eclipse and Android Consultant and Trainer Also works for SAP AG as Product Owner in a Scrum team Maintains http://www.vogella.de Java, Eclipse and Android related Tutorials with ~20 000 visitors per day

3. The challenge Mobile Phone Data in the Cloud

4. Internet creates value for your application

5. Getting the data Polling Pushing

6. Polling is easy 1.) Ask the server if new data is available2.) If new data is available download it3.) Sleep / wait 4.) Repeat 1.)

8. Polling every 5 min can consume 10 % of your battery

9. Pushing Server informs the phone once new data is available Info triggeres a download of data

10. Cloud to Device Messaging Available for Android 2.2 (Beta – Invite only) Requires the Market available on the device Use existing Google connections Light-weight data will be send to the device Message is specific to your application (via permission) Use AlarmManager to keep the connection (Heartbeat)

11. C2DM – Building blocks Gmail User for the application registration Android Application Googles C2DM server Your Application Server

12. C2DM Architecture Googles C2DM Server Android App Your application server

13. C2DM Architecture Request registration ID Unique registration ID Googles C2DM Server Android App Server might send new registration ID

14. C2DM Architecture Sends Registration ID to server Android App Server stores the registration ID

15. Sending messages New HTTP Post message with registration id and authentication token * 200 – ok (with id==ok) 404 – get no auth token 503 – Retry with backoff

16. Return 200 with error QuotaExceeded InvalidRegistration MessageTooBig MissingCollapseKey

17. C2DM Architecture Sends notification message to device Reads the real data from server

18. Building the app

19. Actually its relatively simple Google provides some util classes To register call: C2DMessaging.register(context, Your.Email@gmail.com) Register the Google provided C2DM broadcast receiver in your „AndroidManifest.xml“. Google receiver will forward the information it receives to: context.getPackageName() + ".C2DMReceiver"

20. Your C2DMReceiver Gets the registration ID and send it to your server

21. Permissions

22. Register Googles Receiver

23. Send registration ID to server

24. Further points Best effort delivery: Google will try to deliver all messages but some might get lost Push can send 1024 characters -> not suited for big data, just notification

25. Server can be anything curl, php, For testing build your server also on the phone....

26. Your Java application server

27. from Guillaume Laforge and Patrick Chanezon http://www.slideshare.net/glaforge/google-app-engine-java-groovy-baby

28. Writing Java Webs application is annoyingly hard...

29. Google App Engine GAE allows you to host webapplications on the Google infrastructure. Scalable Infrastructure

30. Google App Engine No Server maintenance Super easy deployment

31. It automatically scales up and down Computing power over time

32. App Engine Architecture Load Balancer App Engine FrontEnd App Engine FrontEnd App Engine FrontEnd AppServer AppServer AppServer

33. GAE Key points Deployment is super simple Supports subset of JPA / JDO for persistence Scalable per definition Free to get started (significant volume)

34. Receiving the registration ID

35. Send out message

36. Funny: Cloud vrs. Mobile Cloud No Threads (Webworkers) No Access to file system Only Key / Value (+JPA, JDO) Time limited for requests 30 Mobile Threads Access to file system SQL Datebase Time limited for Activity 5 secs

37. Summary C2DM powerful and relatively simple to use Google App Engine makes the server site easy

38. Picture CreditsAdd the prefix http://www.sxc.hu/photo Elephant: http://www.sxc.hu/photo/103473 Mouse http://www.sxc.hu/photo/1097314 Liquid http://www.sxc.hu/photo/1109534 Beta 853828 Despair 150108 Old Computer http://www.sxc.hu/photo/1028528 Person with remote http://www.sxc.hu/photo/485640 Victory fingers 906072 Guy with a tie 877661

39. Futher information C2DM Tutorial http://www.vogella.de/articles/AndroidCloudToDeviceMessaging/article.html Google App Engine Tutorial http://www.vogella.de/articles/GoogleAppEngineJava/article.html Chrome to Phone Example http://code.google.com/p/chrometophone/

40. Thank you For further questions: Lars.Vogel@gmail.com http://www.vogella.de http://www.twitter.com/vogella

41. License & Acknowledgements This work is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License See http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.en_US