Using Message Brokers

Ductape provides a Message Broker interface for handling event-based communication between different components of your system. It supports:

1. Publishing Messages – Send messages to a specific event.
2. Subscribing to Events – Listen for messages on a specific event and execute a callback function when triggered.

1. Publishing Messages

Description

Publishing a message allows you to send structured data to a message broker, which other services can subscribe to and consume.

Required Data Fields

• env – Environment where the message should be published (e.g., "production" or "staging").
• event – The event is in the format brokerTag:topicTag
• product_tag – Identifier for the product.
• input – Contains the actual message payload.

Example Usage

await ductape.processor.messageBroker.publish({
  env: "prd",
  event: "sqsbroker:new-orders",
  product_tag: "my_product",
  input: {
    message: {
      orderId: "12345",
      status: "pending",
      customer: {
        name: "John Doe",
        email: "john@example.com"
      }
    }
  }
});

Key Points

• The message field is a flexible object containing event-specific data.
• The event is sent to the appropriate environment and product context.

2. Subscribing to Events

Description

Subscribing to an event allows you to listen for messages from a message broker and execute a callback function when a message arrives.

Required Data Fields

• env – Environment where the subscription should be active.
• event – The event is in the format brokerTag:topicTag
• product_tag – Identifier for the product.
• input – Contains the subscription details, including:
  • callback – Function to handle received messages.

Example Usage

await ductape.processor.messageBroker.subscribe({
  env: "prd",
  event: "sqsbroker:new-orders",
  product_tag: "my_product",
  input: {
    callback: async (message) => {
      console.log("Received message:", message);
      // Process the message (e.g., update order status)
    }
  }
});

Key Points

• The callback function receives the message and executes necessary logic.
• The topicTag helps in identifying different event listeners.

Choosing the Right Method

Method	Use Case
Publishing Messages	Use when you need to send an event to the message broker.
Subscribing to Events	Use when you need to listen for events and process incoming messages.