Until a connection is established, all outgoing requests will return `ErrDisconnected`.

# Usage

## Single Payload Requests

Single payload requests are requests and responses that are sent in a single message.
In essence, they are `[]byte` -> `[]byte, error` functions.

It is not possible to return *both* an error and a response.

  # qos level is set to 1
  client.subscribe("minio", 1)

def on_message(client, userdata, msg):
    print(msg.payload)

# client_id is a randomly generated unique ID for the mqtt broker to identify the connection.
client = mqtt.Client(client_id="myclientid",clean_session=False)

client.on_connect = on_connect
client.on_message = on_message

client.connect("localhost",1883,60)
client.loop_forever()
```

#### **4.2.2  Run the Spark shell:**

```
./bin/spark-shell --master yarn-client --driver-memory 512m --executor-memory 512m
```

The command should produce an output as shown below. (with additional status messages):

```
Spark context Web UI available at http://172.26.236.247:4041
Spark context available as 'sc' (master = yarn, app id = application_1490217230866_0002).
Spark session available as 'spark'.
Welcome to