#Google Cloud Messaging (GCM) Demo app

This repo contains an end-to-end demo of GCM, including a server-side implementation as well as a gcm client (Android app) implementation. See the docs on developer.android.com for information regarding the setup that needs to be done on the GCM side.

##Server-side

In this case, the server-side is implemented in Scala using Play, because…well, just because. Uses the GCM REST api to send messages to clients. To run the app, you'll need a GCM API key, which can be passed in via the gcm.api.key property. By default, Play will look for an environment property named GCM_API_KEY. Uses H2 by default, but you can override this by specifying your own db.default.url and db.default.driver (tho' no guarantees that it will work with every database - I've only tested it with H2 and PostgreSQL).

##Service endpoints

The following REST-ish endpoint are exposed by the service (there's a RAML file in gcm-server that has the schema of the servce - purely there for documentation purposes):

###Create a new session

POST /sessions/:id
{
	"gcm_id":"a gcm registration id",
	"os_version": "android os version",
	"app_version": "app version"
}

###Retrieve a session

GET /sessions/:id

###Delete a session

DELETE /sessions/:id

###Post a message

POST /sessions/:id/message
{
	"content":"hello GCM!"
}

##Running the server

To start the server (with H2):

$ start -Dgcm.api.key=<your GCM api key>

##GCM client

The GCM client is implemented as an Android application, which registers with GCM, then submits the GCM registration ID, along with a session identifier to the server-side (see above). The build takes two parameters, gcmSenderId and appServerUrl to specify the GCM sender id and the url of the application server (again, above).

To build the apk:

gradle packageDebug -PgcmSenderId=<your GCM sender id> -PappServerUrl=<the url for your server>