Sending a notification-only payload to GCM using AWS SNS

Question

I am trying to send mobile push notifications to GCM via AWS SNS. According to the latest GCM 3.0 documentation, one may include either a "notification" payload or a "data" payload (or both). If you send a notification payload, then GCM will take care of showing the notification on the end-user device for you.

Using the Amazon SNS Console, I tried sending a notification-only payload, but I encountered the following error:

Invalid parameter: Message Reason: Invalid notification for protocol GCM: data key is expected in the json message (Service: AmazonSNS; Status Code: 400; Error Code: InvalidParameter)

I'm sending:

{
  "GCM":"{\"notification\":{\"title\":\"Test Message\"}}"
}

I suspect this might be an issue with SNS still conforming to a previous version of GCM and therefore it expects a "data" key, but I'm not sure. Is anyone else having a similar problem or have any experience with this? Thanks!

EDIT: To clarify, I want to send GCM a notification payload and have it display an alert to the user automatically as described in the documentation. Right now, I'm beginning to wonder if SNS is even forwarding the notification payload to the device.

What if you add the data property and just leave it with an empty string? — cYrixmorten
@cYrixmorten, good point. That would certainly work, but what I really want to happen is for GCM to recognize the notification payload and display the alert automatically as documented. That is not happening when I send an empty data string. — weiy
Alright, just thought it might have been 'clever' enough to recognize that the data value was empty. I only have experience with implementing the GCM installation handling myself (long time ago and tedious) and then I have been using parse.com. The latter is working really well for me and is easy to setup. — cYrixmorten

weiy weiy · Accepted Answer · 2015-08-21T21:18:22

To answer my own question, I received the following from AWS Support on their forums:

You are correct, SNS does not currently support GCM's "notification" payload type as described in their documentation. SNS supports the initial "data" payload type only but we are actively working on a solution to support the "notification" type. In the meantime, the "data" payload works the same except the client app is responsible for processing data messages as it has in the past.

So until SNS supports the GCM notification payload, you have to handle the display of notifications yourself by extending the class GcmListenerService and overriding the method onMessageReceived.

UPDATE 10/2015: It seems SNS has now implemented support for the GCM notification payload. If you include both the "data" and "notification" payloads, "notification" will take precedence. I only observed this behavior on SNS, but could not find any AWS blog/articles announcing this.

Sending a notification-only payload to GCM using AWS SNS

1 Answers