Message

Kind: Interface

Source: packages/microservices/external/kafka.interface.ts

Part of: Microservices

Message represents a Kafka record consumed or produced by the microservices transport layer. It stores the message payload, optional key, partition metadata, headers, and the Kafka-provided timestamp so downstream code can process records consistently.

Properties

Diagram

mermaid
graph LR
  Producer[Kafka Producer] --> Message[Message]
  Message --> Key[key: Buffer | string | null]
  Message --> Value[value: Buffer | string | null]
  Message --> Partition[partition: number]
  Message --> Headers[headers: IHeaders]
  Message --> Timestamp[timestamp: string]
  Message --> Consumer[Kafka Consumer]

Usage

ts
import type { Message } from './kafka.interface';

function handleKafkaMessage(message: Message): void {
  const payload =
    message.value === null
      ? null
      : Buffer.isBuffer(message.value)
        ? message.value.toString('utf8')
        : message.value;

  console.log({
    key: message.key?.toString(),
    partition: message.partition,
    timestamp: new Date(message.timestamp),
    headers: message.headers,
    payload,
  });
}

AI Coding Instructions

• Treat key and value as nullable; check for null before decoding or parsing them.
• Support both Buffer and string payloads, using Buffer.isBuffer() before calling buffer-specific methods.
• Preserve partition, headers, and timestamp when forwarding or transforming a message.
• Parse timestamp only when needed; Kafka timestamps are represented as strings in this interface.
• Use headers for cross-cutting metadata such as tracing, correlation IDs, and content type.