16.11.2013 DevFest Central Italy @ Rome Google Developer Group Perugia http://gdg-perugia.org 

+EmanuelePalazzetti Manager Google Developer Group Perugia @palazzem github.com/emanuele-palazzetti [email protected] Who am I? 

Wake up your Android with Google Cloud Messaging 

Google Cloud Messaging? Not yet… ...let’s talk about something else Google Cloud Messaging 

Conference organization! 

It’s not easy to organize a conference ● find speakers ● event marketing ● prepare website, flyer, etc… ● communicate with attendees: ○ before ○ during ○ after The problem 

Hey! This is a DevFest! We should talk about code! What? 

DevFest Android app (use case) ● all italian DevFest list during the year ● for each DevFest provide talks scheduling ● some notifications Android app 

DevFest Android app (end-user requirements) ● notifications without any running application ● notifications across all owned devices ● real time notifications (delay, rooms swap, etc...) ● hey! don’t exhaust my battery! Android app 

Google Cloud Messaging If you have an Android application and a server you should use it! You can finally throw out the “refresh button” Even with your third-party application server Google Cloud Messaging 

Google Cloud Messaging ● Integrated with Google Play Services ● Available back to Froyo (remember about dropped support) NOTE: old GCM standalone implementation is deprecated! Use the GoogleCloudMessaging API instead! Google Cloud Messaging 

Pros ● No battery consumption (server push) ● App doesn’t need to be running to receive messages ● Reduces update latency ● Transmit messages to multiple devices Google Cloud Messaging 

Registration Google Cloud Messaging Device Registration 

Registration Google Cloud Messaging Registration ID 

Registration Google Cloud Messaging Registration ID Your server 

Send a message Google Cloud Messaging Your server Message to: registrationId Message 

What happen if user devices are offline? ● Google provides automatic queue management ● When device come back online again, all messages are delivered ● We can have 100 stored messages (in the queue) and if you reach that limit, all messages are discarded and a special message is delivered NOTE: use the special message to manage a full sync! Google Cloud Messaging 

Getting started 

Application server requirements: ● Able to communicate with your client (endpoints) ● Able to store the API key and client registration IDs ● Able to fire off properly formatted requests to the GCM server ● Able to generate message IDs to identify each message it sends Application server 

Requests to GCM server ● You can use two different protocols: HTTP or CCS (XMPP) ● JSON message: ○ HTTP: sent as HTTP POST ○ CCS: message is encapsulated in XMPP message Application server 

Send-to-sync message Send-to-sync message with collapse key 

Message with payload max 4kb payload useful to avoid further connections! 

Android client Android manifest 

Android client Some best practices before continue ● If you are using Play Services SDK, always perform a compatibility check in Activity onCreate() and onResume() ● Write your own wrapper around these methods: 

Android client Request registrationId 

Android client About storing your registrationId: ● It’s better to generate a new one if you update your application ● If you use Google Backup Service, avoid to backup registrationId 

Android client Simple BroadcastReceiver to manager GCM messages 

Android client Done! Remember: ● Register your Google API_KEY ● Configure AndroidManifest.xml ● Android registration on GCM ● Send received registrationId to your application server (and store it) ● Prepare your broadcast receiver ● Start sending GCM messages from your server! 

Hands on code! https://developers.google.com/cloud/samples/mbs/ 

+EmanuelePalazzetti Manager Google Developer Group Perugia @palazzem github.com/emanuele-palazzetti [email protected] Thanks for your attention! 

Questions?