Subscribing to IOT topic in Android

Question

I'm trying to subscribe to a topic via my Android application. Even though it connects successfully subscription fails. As soon as I perform subscription call, IOT connectivity fails and gives an error log as stated below. Want to Know where have I done any wrong coding ? All the resources of IOT policy is given due to testing purposes to find a clue.

{
  "Version": "2012-10-17",
  "Statement": [
   {
      "Effect": "Allow",
      "Action": "iot:*",
      "Resource": "*"
   }
 ]
}

I referred AWS-amplify for my development. https://aws-amplify.github.io/docs/android/pubsub

1 .Connecting to IOT

    private var mAWSMobileClient : AWSMobileClient = AWSMobileClient.getInstance()
    private lateinit var mIotDataManager: AWSIotMqttManager
    private lateinit var mAttachedPolicyReq: AttachPolicyRequest
    private lateinit var mAwsIOTClient: AWSIotClient
    private lateinit var mAwsCredentials: AWSCredentials

 private fun connectToIOT() {
        Thread(Runnable {
            var mDeviceIdentity = Settings.Secure.getString(this.contentResolver, Settings.Secure.ANDROID_ID)

            mIotDataManager = AWSIotMqttManager(mDeviceIdentity, <iot endpoint>)
            mIotDataManager.keepAlive = 50
            mIotDataManager.isAutoReconnect = false
            mIotDataManager.connectionStabilityTime = 100

            mAwsCredentials = mAWSMobileClient.awsCredentials
            mAwsIOTClient = AWSIotClient(mAWSMobileClient)
            mAwsIOTClient.setRegion(Region.getRegion(Regions.AP_SOUTHEAST_2))

            mAttachedPolicyReq = AttachPolicyRequest()
            mAttachedPolicyReq.policyName = "test_policy"
            mAttachedPolicyReq.target = mAWSMobileClient.identityId
            mAwsIOTClient.attachPolicy(mAttachedPolicyReq)

            try {
                mIotDataManager.connect(mAWSMobileClient, object : AWSIotMqttClientStatusCallback {
                    override fun onStatusChanged(
                        status: AWSIotMqttClientStatusCallback.AWSIotMqttClientStatus?,
                        throwable: Throwable?
                    ) {
                        when (status) {
                            AWSIotMqttClientStatusCallback.AWSIotMqttClientStatus.ConnectionLost -> {}

                            AWSIotMqttClientStatusCallback.AWSIotMqttClientStatus.Connected -> {}

                            AWSIotMqttClientStatusCallback.AWSIotMqttClientStatus.Connecting -> {}

                            AWSIotMqttClientStatusCallback.AWSIotMqttClientStatus.Reconnecting -> {}

                        else -> {

                        }
                    }
                }
            })
        } catch (e: Exception) {
            Log.d("IOT Data Manager Connection Errror : $e")
        }
    }).start()
}

Subscription Method

fun subscribeToThing() {
        if(mConnected) {
            Thread(Runnable {
                mThingsName = "$mThingsName/shadow/get/accepted"
                var message: String? = null
                try {
                    mIotDataManager.subscribeToTopic(
                        mThingsName,
                        AWSIotMqttQos.QOS1,
                        object : AWSIotMqttNewMessageCallback {
                            override fun onMessageArrived(topic: String?, data: ByteArray?) {

                                try {
                                    message = String(data!!, Charsets.UTF_8)
                                } catch (e: UnsupportedEncodingException) {
                                    Log.d("Unsupported Encoding error :$e")
                                }
                            }
                        })
                } catch (e: Exception) {
                    Log.d("Subscription error :$e")
                }
        }).start()
    } else {
        Log.d("IOT Not Connected")
        }
}

Result Log :

W/AWSIotMqttManager: connection is Lost

Subscription error :com.amazonaws.AmazonClientException: Client error when subscribing.

Raphael Kim Raphael Kim · Accepted Answer · 2019-12-30T19:26:09

I see that you are using AWSMobileClient. Perhaps you did not initialize the mobile client instance prior to using the IOT client? The details are outlined in the following documentation.

Subscribing to IOT topic in Android

1 Answers