Message Hub

This event allows you to connect functions to IBM Message Hub, a scalable message bus in the cloud, based upon Apache Kafka. Functions are invoked with messages that are added to a Kafka topic.

This event utilise the trigger feed provided by the Message Hub package.

Setup

IBM Message Hub instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Message Hub service credentials bound to a package with the following name:

/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1

Configuration

Users need to pass the message hub credentials and the kafka topic to listen for messages on when defining the event.

Using Package Credentials

Rather than having to manually define all authentication properties needed by the Message Hub trigger feed, you can reference a package which provides these properties as default parameters.

Developers only need to add the kafka topic to listen for messages on with each event.

# serverless.yaml
functions:
  index:
    handler: users.main
    events:
      - message_hub:
          package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
          topic: my_kafka_topic

Optional parameters json, binary_key, binary_value are also supported.

The configuration will create a trigger called ${serviceName}_${fnName}_messagehub_${db} and a rule called ${serviceName}_${fnName}_messagehub_${db}_rule to bind the function to the database update events.

The trigger and rule names created can be set explicitly using the trigger and rule parameters.

Using Manual Parameters

Authentication credentials for the Message Hub event source can be defined explicitly, rather than using pulling credentials from a package.

# serverless.yaml
functions:
  index:
    handler: users.main
    events:
      - message_hub:
          topic: my_kafka_topic
          brokers: afka01-prod01.messagehub.services.us-south.bluemix.net:9093
          user: USERNAME
          password: PASSWORD
          admin_url: https://kafka-admin-prod01.messagehub.services.us-south.bluemix.net:443
          json: true
          binary_key: true
          binary_value: true

topic, brokers, user, password and admin_url are mandatory parameters.

Binding Multiple Functions

Other functions can bind to the same database event being fired using the inline trigger event and referencing this trigger name.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - message_hub:
                package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
                topic: my_kafka_topic
                trigger: log_events
                rule: connect_index_to_kafka
     another:
        handler: users.another
        events:
            - trigger: log_events

Event Details

The payload of that trigger event will contain a messages field which is an array of messages that have been posted since the last time your trigger fired.

The JSON representation of a sample event is as follows:

{
  "messages": [
    {
      "partition": 0,
      "key": "U29tZSBrZXk=",
      "offset": 421760,
      "topic": "mytopic",
      "value": "Some value"
    }
  ]
}

For more details on the exact semantics of the message properties, please see the trigger feed documentation.

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Message Hub

This event allows you to connect functions to IBM Message Hub, a scalable message bus in the cloud, based upon Apache Kafka. Functions are invoked with messages that are added to a Kafka topic.

This event utilise the trigger feed provided by the Message Hub package.

Setup

IBM Message Hub instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Message Hub service credentials bound to a package with the following name:

/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1

Configuration

Users need to pass the message hub credentials and the kafka topic to listen for messages on when defining the event.

Using Package Credentials

Rather than having to manually define all authentication properties needed by the Message Hub trigger feed, you can reference a package which provides these properties as default parameters.

Developers only need to add the kafka topic to listen for messages on with each event.

# serverless.yaml
functions:
  index:
    handler: users.main
    events:
      - message_hub:
          package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
          topic: my_kafka_topic

Optional parameters json, binary_key, binary_value are also supported.

The configuration will create a trigger called ${serviceName}_${fnName}_messagehub_${db} and a rule called ${serviceName}_${fnName}_messagehub_${db}_rule to bind the function to the database update events.

The trigger and rule names created can be set explicitly using the trigger and rule parameters.

Using Manual Parameters

Authentication credentials for the Message Hub event source can be defined explicitly, rather than using pulling credentials from a package.

# serverless.yaml
functions:
  index:
    handler: users.main
    events:
      - message_hub:
          topic: my_kafka_topic
          brokers: afka01-prod01.messagehub.services.us-south.bluemix.net:9093
          user: USERNAME
          password: PASSWORD
          admin_url: https://kafka-admin-prod01.messagehub.services.us-south.bluemix.net:443
          json: true
          binary_key: true
          binary_value: true

topic, brokers, user, password and admin_url are mandatory parameters.

Binding Multiple Functions

Other functions can bind to the same database event being fired using the inline trigger event and referencing this trigger name.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - message_hub:
                package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
                topic: my_kafka_topic
                trigger: log_events
                rule: connect_index_to_kafka
     another:
        handler: users.another
        events:
            - trigger: log_events

Event Details

The payload of that trigger event will contain a messages field which is an array of messages that have been posted since the last time your trigger fired.

The JSON representation of a sample event is as follows:

{
  "messages": [
    {
      "partition": 0,
      "key": "U29tZSBrZXk=",
      "offset": 421760,
      "topic": "mytopic",
      "value": "Some value"
    }
  ]
}

For more details on the exact semantics of the message properties, please see the trigger feed documentation.