This directory contains samples for Google Cloud IoT Core. Google Cloud IoT Core allows developers to easily integrate Publish and Subscribe functionality with devices and programmatically manage device authorization.

We recommend using Java 8 JDK for this example.

These samples use the Apache Maven build system. Before getting started, be sure to download and install it. When you use Maven as described here, it will automatically download the needed client libraries.

If you haven't already created a project, create one now. Projects enable you to manage all Google Cloud Platform resources for your app, including deployment, access control, billing, and services.

1. Open the Cloud Platform Console.
2. In the drop-down menu at the top, select Create a project.
3. Give your project a name.
4. Make a note of the project ID, which might be different from the project name. The project ID is used in commands and in configurations.

Note that before you can run the sample, you must configure a Google Cloud PubSub topic for Cloud IoT as described in the parent README.

Before running the samples, you can set the GOOGLE_CLOUD_PROJECT and GOOGLE_APPLICATION_CREDENTIALS environment variables to avoid passing them to the sample every time you run it.

For example, on most *nix systems you can do this as:

export GOOGLE_CLOUD_PROJECT=your-project-id
export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/[FILE_NAME].json"

This sample requires you to have authentication setup. Refer to the Authentication Getting Started Guide for instructions on setting up credentials for applications.

Run the following command to install the libraries and build the sample with Maven:

mvn clean compile assembly:single

Before you begin, you will need to create the Google Cloud PubSub message queue, create a subscription to it, create a device registry, and add a device to the registry.

1. Create the PubSub topic as:

   gcloud pubsub topics create java-e2e

2. Create the subscription:

   gcloud pubsub subscriptions create java-e2e-sub --topic=java-e2e

3. Create the device registry:

   gcloud iot registries create java-ed2e-registry --event-notification-config=topic=java-e2e --region=us-central1

4. Run the generate_keys.sh shell script:

   ../generate_keys.sh

5. Add a device to the registry using the keys you generated:

   gcloud iot devices create device-id --registry=java-ed2e-sub --region=us-central1 --public-key=path=./rsa_cert.pem,type=RS256

To run this sample:

mvn exec:java \
    -Dexec.mainClass="com.example.cloud.iot.endtoend.CloudiotPubsubExampleServer" \
    -Dexec.args="-project_id=<your-iot-project> \
                -pubsub_subscription=<your-pubsub-subscription>"

To run this sample:

mvn exec:java \
  -Dexec.mainClass="com.example.cloud.iot.endtoend.CloudiotPubsubExampleMqttDevice" \
  -Dexec.args="-project_id=<your-iot-project> \
               -registry_id=<your-registry-id> \
               -device_id=<device-id> \
               -private_key_file=<path-to-keyfile> \
               -algorithm=<RS256|ES256>"

For example, if your project ID is blue-jet-123, your device registry id is my-registry, your device id is my-device and you have generated your credentials using the generate_keys.sh script provided in the parent folder, you can run the sample as:

mvn exec:java \
    -Dexec.mainClass="com.example.cloud.iot.endtoend.CloudiotPubsubExampleMqttDevice" \
    -Dexec.args="-project_id=blue-jet-123 \
                 -registry_id=my-registry \
                 -device_id=my-device \
                 -private_key_file=../rsa_private_pkcs8 \
                 -algorithm=RS256"