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ClearBlade provides a native integration for high-performance interactions with Google Pub/Sub. This is ideal for sending MQTT messages into Google Cloud services or integrating data from other Google Cloud services directly with your ClearBlade application.

Publish

ClearBlade uses the Pub/Sub Golang library, which leverages a persistent TCP connection under the covers.

The topics entered during Pub/Sub connection creation will be added as subscribers to the topic tree. The Pub/Sub connection will implement the client interface in core_messaging/broker/client_manager.go. Use the Publish function to forward messages.

Endpoints:

/admin/{systemKey}/{name}/google-integrations/pub-sub

GET, POST, PUT, and DELETE support

POST:

Body required. The body can have IoT Core and non-IoT Core topics. type and target are required for IoT Core topics. type can be 1 for events and 2 for state:

{
    "credentials_map": { // This is the service account JSON object
        "type": "service_account",
        "project_id": "myprojectid",
        "private_key_id": "blahblahblah",
        "private_key": "<priv_key>",
        "client_email": "a@a.com",
        "client_id": "9126871624161341",
        "auth_uri": "https://accounts.google.com/o/oauth2/auth",
        "token_uri": "https://oauth2.googleapis.com/token",
        "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
        "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/dahjkdhajkd%40dajsdgajdadsad.iam.gserviceaccount.com"
    },
    "project_id": "myprojectid",
    "topics": [ // This is to send data to Google Pub/Sub
        {"path": "iotdemo"}, // Non IoT Core topic
        {"path": "/devices/+/events", "type": 1, "target": "performance-testing"}, // IoT Core topic
        {"path": "/devices/+/events/sub", "type": 1, "target": "performance-testing-sub", "sub_folder": "sub"}, // IoT Core topic
        {"path": "/devices/+/state", "type": 2, "target": "performance-testing-state"} // IoT Core topic
    ],
    "forwarders": { // This is to receive Google Pub/Sub messages
      "ack_strategy": 0,
      "poll_rate": 5000,
      "max_messages_per_poll": 2,
      "subscriptions": [
          {
              "mqtt_topic": "pubsub",
              "pubsub_subscription": "test-sub"
          }
      ]
  }
}

path is the MQTT topic on the ClearBlade broker that the Pub/Sub client will subscribe to internally. For Non IoT Core integrations, path must match the Google Pub/Sub topic being published to exactly. Hence, in this case path cannot contain wildcards (+, #).

type is the topic type. 1 is for event and 2 is for state. For Non IoT Core integrations, type is not used.

target is the Google Pub/Sub topic the Pub/Sub client will publish to. sub_folder is for the event's topic if it has a subfolder. For Non IoT Core integrations, target is not used.

GET:

No query support. Admin or Dev.

Returns the same object as the POST body.

/admin/{systemKey}/google-integrations/pub-sub

GET and DELETE support only. GET obtains all Pub/Sub connections for that system, and DELETE deletes all.

Receiving data

The following parameters exist for setting up your Google Pub/Sub forwarders to ClearBlade MQTT:

ack_strategy: 0 = ack immediately, 1 = never ack. For now, 0 should always be used.

poll_rate: Time (ms) between sending message batches to the broker. 0 will send messages immediately.

max_messages_per_poll: Max number of messages to send in a single batch to the broker. Implicit minimum value of 1.

Messages are received by ClearBlade as soon as possible from Google. ClearBlade will buffer them internally and send them in batches as defined above.

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