pubsub.md

PubSub

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This sample uses the Message Broker for AWS IoT to send and receive messages through an MQTT connection.

On startup, the device connects to the server, subscribes to a topic, and begins publishing messages to that topic. The device should receive those same messages back from the message broker, since it is subscribed to that same topic. Status updates are continually printed to the console. This sample demonstrates how to send and receive messages on designated IoT Core topics, an essential task that is the backbone of many IoT applications that need to send data over the internet. This sample simply subscribes and publishes to a topic, printing the messages it just sent as it is received from AWS IoT Core, but this can be used as a reference point for more complex Pub-Sub applications.

Your IoT Core Thing's Policy must provide privileges for this sample to connect, subscribe, publish, and receive. Below is a sample policy that can be used on your IoT Core Thing that will allow this sample to run as intended.

(see sample policy)

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "iot:Publish",
        "iot:Receive"
      ],
      "Resource": [
        "arn:aws:iot:region:account:topic/test/topic"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Subscribe"
      ],
      "Resource": [
        "arn:aws:iot:region:account:topicfilter/test/topic"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Connect"
      ],
      "Resource": [
        "arn:aws:iot:region:account:client/test-*"
      ]
    }
  ]
}

Replace with the following with the data from your AWS account:

• <region>: The AWS IoT Core region where you created your AWS IoT Core thing you wish to use with this sample. For example us-east-1.
• <account>: Your AWS IoT Core account ID. This is the set of numbers in the top right next to your AWS account name when using the AWS IoT Core website.

Note that in a real application, you may want to avoid the use of wildcards in your ClientID or use them selectively. Please follow best practices when working with AWS on production applications using the SDK. Also, for the purposes of this sample, please make sure your policy allows a client ID of test-* to connect or use --client_id <client ID here> to send the client ID your policy supports.

How to run

To Run this sample from the samples folder, use the following command:

# For Windows: replace 'python3' with 'python' and '/' with '\'
python3 pubsub.py --endpoint <endpoint> --cert <file> --key <file>

You can also pass a Certificate Authority file (CA) if your certificate and key combination requires it:

# For Windows: replace 'python3' with 'python' and '/' with '\'
python3 pubsub.py --endpoint <endpoint> --cert <file> --key <file> --ca_file <file>