Configure a script consumer

Use a script to import and process data from your Kafka environment.

Before you begin

• Role required: integration_hub_admin
• This consumer requires a Stream Connect subscription. For more information, see https://www.servicenow.com/now-platform/workflow-data-fabric.html.
• The ServiceNow Stream Connect Installer [com.glide.hub.stream_connect.installer] plugin is required.

About this task

To configure a consumer, you need to create two records.

1. The consumer record, which specifies how to import and process data.
2. A record for the Kafka stream, which defines the stream of data to your consumer.

This task covers the consumer creation. For instructions on creating a Kafka stream, see Create a Kafka stream.

Procedure

1. Navigate to All > IntegrationHub > Consumers > Script Consumer.
2. Select New.
3. In the form, fill in the fields.

   Table 1. Script consumer

   Field	Description
   Name	Name of the Script consumer.
   Delivery guarantee	If there's a node failure, option to specify the delivery guarantee for incoming messages. Select one of the following. No lost but duplicates: All messages are delivered at least once. Some messages might be delivered more than once. Once or not at all: A message isn’t delivered more than once. Some messages might not be delivered at all.
   Serialization format	The serialization format for the message. Select one of the following. Plain Text: Select this option for any plain-text messages. This is the default format. Encoded: Select this option for messages in an Apache Avro format. Converting plain-text messages to an Avro format requires a schema. Select the schema registry in the Schema registry field. For more information on schemas, see Schema management in Stream Connect.
   Event consumer	Script to use to consume the messages received from the Kafka topic.
   Application	Application scope for the Transform Map Consumer.
   Schema registry	Registry for the selected schema. Select one of the following. Standalone Schema Registry Confluent Schema Registry This field appears only when the Serialization format is set to Encoded. For the Confluent Schema Registry, if the received message's schema ID isn't in the schema table, the system imports the schema dynamically, using the configured REST connection.

4. Select Save.

Example

This example shows a sample script for processing messages.

(function process(messages) {
 // Add your code here to consume kafka messages 
 // sample message [ { 'key' : 'message_key' , 'message' : 'message' , 'headers' : [ { 'key' : 'header_key' , 'value' : 'header_value' } ] } ] 

 for (var i = 0; i < messages.length; i++) {
     var message = JSON.parse(messages[i].message);
     gs.info('Number ' + message.number + ', short description ' + message.short_description +
         ', headers ' + JSON.stringify(messages[i].headers));
 }
})(messages);

What to do next

Create a Kafka stream for this consumer. After the stream is activated, you can start receiving messages from your Kafka environment.