smoothie-gcm

This is fork of gcm-erlang optimized to use with smoothie.

This software provides an Erlang client for Google Cloud Messaging.

Features

Using smoothie-gcm you can:

• Start several gen_servers representing different GCM applications defined by different GCM API keys
• Send notification messages to Android mobile devices registered to your specific application and registered to GCM using a specific registration id

So far smoothie-gcm does only provide support for JSON messages since GCM does not allow to send multicast messages using plain text.

Setting Up

You can use gcm_app as a dependency in your rebar.config:

{deps, [
    {smoothie_gcm, ".*", {git, "https://github.com/tapsters/smoothie-gcm.git", {tag, "master"}}}
]}.

Starting GCM API Worker (one for each GCM application)

While smoothie-gcm is running you can start several supervised gen_servers, one for each GCM application. Every gen_server is defined by an atom used internally for registration and by a GCM API key.

1> sm_gcm:start(foo, "myapikey").
{ok,<0.60.0>}
2> sm_gcm:start(bar, "myotherapikey").
{ok,<0.65.0>}

You can stop a gen_server representing a GCM Application using:

3> sm_gcm:stop(foo).

Sending Messages

At any time you can send a GCM message to one or more mobile devices by calling:

4> sm_gcm:push(RegisteredName, RegIds, Message).

or by calling:

5> sm_gcm:sync_push(RegisteredName, RegIds, Message).

Where RegistereName is the atom used during registration, RegIds is a list (max 1000 elements) of Registration Ids specified as Erlang binaries (e.g., <<"APA91bHun4MxP5egoKMwt2KZFBaFUH-1RYqx...">>) and Message is an Erlang term representing the data you want to send to the device.

The JSON message is built yaws-json2 in the module sm_gcm.erl and in the end will have the following form:

{
  "registration_ids" : ["APA91bHun4MxP5egoKMwt2KZFBaFUH-1RYqx..."],
  "data" : {
    "message" : "a message"
  },
  "time_to_live" : 3600,
  "collapse_key" : "your_update"
}

You can send this message using:

6> sm_gcm:push(default, RegIds1, {struct, [{"data", {struct, [{"message", "a message"}]}},
6>                                         {"time_to_live", 3600},
6>                                         {"collapse_key", "your_update"}]}).

or simply:

7> sm_gcm:push(default, RegIds1, {struct, [{"data", {struct, [{"message", "a message"}]}}]}).

smoothie-gcm will push the message for you to Google Cloud Messaging servers and will parse the JSON provided as result.

In order to understand errors see: Interpreting an error response.

Note

Some of the concepts I used for building this Erlang application are based on this blog post and on this Erlang application for APN.