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Kafka Eventsource

Kafka is a versatile messaging system designed to securely transfer data between various systems. Its functionality can be tailored through configuration, allowing it to serve as a reliable conduit for real-time event tracking or even function as a replicated distributed database. While it's often colloquially labeled as a queue, it's more precisely described as a hybrid system that combines characteristics and trade-offs from both queue and database systems.

A brief description of how to use Kafka plug-in in our godspeed framework as Data Source as Event Source.

How to Add​

  • Open a godspeed project and add the plugin using cli:
  godspeed plugin add @godspeedsystems/plugins-kafka-as-datasource-as-eventsource

After installation, you will find auto-generated files in your project related to the plugin at src/datasources/types/kafka.ts and src/datasources/kafka.yamland src/eventsources/types/kafka.ts and src/datasources/kafka.yaml.

Update configuration file based on your requirements in​

src/eventsources/kafka.yaml

kafka config ( src/datasources/kafka.yaml )

type: kafka
clientId: "kafka_proj"
brokers: ["kafka:9092"]

Define kafka event for Producer ( src/events/kafka_pub.yaml )​

In the event, we establish an HTTP endpoint that accepts parameters such as the topic name and message content. When this endpoint is invoked, it triggers the datasource.kafka.producer function. This function, in turn, takes the provided topic name and message as input arguments and performs the task of publishing the message to the specified Kafka topic.

# event to Publish

http.post./kafka-pub:
  fn: kafka-publish
  body:
    content:
      application/json:
        schema:
          type: object
          properties:
            message:
              type: string
          required: ['message']

kafka workflow for Producer ( src/functions/kafka-publish.ts )​

import { GSContext, PlainObject, GSStatus } from "@godspeedsystems/core";
 /**
  * Kafka producer function - publishes message from request body to a Kafka topic
 */
export default async function (ctx: GSContext, args: PlainObject): Promise<GSStatus> {
  const { datasources, inputs, logger } = ctx;
  const { message } = inputs.data.body;

  if (!message) {
    return new GSStatus(false, 400, undefined, undefined, "Message is required");
  }

  const kafkaProducer = datasources.kafka?.producer;

  if (typeof kafkaProducer !== "function") {
    return new GSStatus(false, 500, undefined, undefined, "Kafka producer function not found");
  }

  try {
    const result = await kafkaProducer({
      topic: "publish-producer1",
      message
    });

    logger.info("Kafka message published successfully: %o", result);

    return new GSStatus(true, 200, undefined, "Message published to Kafka");
  } catch (err) {
    logger.error("Kafka publish failed: %o", err);
    return new GSStatus(false, 500, undefined, undefined, "Failed to publish to Kafka");
  }
}

Example usage EventSource (Consumer):​

Update configuration file based on your requirements in Eventsources/kafka.yaml.

kafka config ( kafka.yaml )​

type: kafka
groupId: "kafka_proj"

kafka event for consumer (src/events/kafka_pub.yaml)​

To use Consumer we need to follow the below event key format.

 kafka.{Topic}.{GroupId}

The consumer event is triggered whenever a new message arrives on the specified topic. Upon triggering, it retrieves the incoming message and forwards it to the kafka_consume function. Inside this function, the incoming message is processed, and the result is then returned.

# event to consume data from Topic
kafka.publish-producer1.kafka_proj:   # event key
  id: kafka_consumer
  fn: kafka_consume
  body:
    description: The body of the query
    content:
      application/json: 
        schema:
          type: string

kafka workflow for Consumer​

(src/functions/kafka_consume.ts)

import { GSContext, PlainObject, GSStatus } from "@godspeedsystems/core";
/**
 * Kafka consumer function - returns the consumed Kafka message
 */
export default function (ctx: GSContext, args: PlainObject): GSStatus {
  const { inputs } = ctx;

  return new GSStatus(true, 200, undefined, inputs.data);
}

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