Alexa: Increasing and Decreasing brightness of device

The Alexa skill does not work with "Increase/Decrease device_name to percentage".

Example : Me - Alexa, Increase device by 20%

Alexa - Sorry the device is not responding.

However, when I check in Alexa application it increases the brightness by 20%.

Request :

{
    "directive": {
        "header": {
            "namespace": "Alexa.BrightnessController",
            "name": "AdjustBrightness",
            "payloadVersion": "3",
            "messageId": "0d-4605-9d50",
            "correlationToken": ""
            },
            "endpointId": "device",
            "cookie": {
                "Load": "LOAD_1",
                "NodeIndex": "0",
                "Type": "LIGHT",
                "Name": "96005E",
                "Thing": "device_0001"
            }
        },
        "payload": {
            "brightnessDelta": 20
        }
    }
}

Response :

{
    "context": {
        "properties": [
            {
                "namespace": "Alexa.BrightnessController",
                "name": "brightness",
                "value": 71,
                "timeOfSample": "2017-02-03T16:20:50.52Z",
                "uncertaintyInMilliseconds": 500
            }
        ]
    },
    "event": {
        "header": {
            "namespace": "Alexa",
            "name": "Response",
            "payloadVersion": "3",
            "messageId": "48CE-BBE5",
            "correlationToken": ""
        },
        "endpoint": {
            "scope": {
                "type": "BearerToken",
                "token": "access-token-from-Amazon"
            },
            "endpointId": "device"
        },
        "payload": {}
    }
}

When I command to "Set device to 20%" it works fine, with "OK" response from Alexa.

Note : I have tried Alexa.PercentageController it still gave me the same error response.

Solution

So, I finally figured it out, all credit goes to the Amazon team. The problem was with the response which I was sending to Alexa. The response I was sending was async, but Alexa requires sync response.

This is what the Amazon team replied with:

https://developer.amazon.com/docs/device-apis/alexa-interface.html#response

Note: that a synchronous response does not include a bearer token, scope, etc.

If your intention is to follow the asynchronous response pattern then you first need to send a synchronous deferred response message and then follow up with an asynchronous response which you send to the Alexa event gateway.

Note: that most of our lighting partners do not use the deferred response pattern and instead just respond to the original control message with a synchronous message. You would typically only follow the deferred response pattern with a light in rare conditions where your backend architecture necessitates this flow.