@mhlabs/events-client

This is still under development and should not be used in production code

A thin client for Amazon EventBridge that has as purpose to enforce a message pattern convention following this contract:

{
    "source": "my-source",
    "detail-type": "my-detail-type"
    ...,
    "detail": {
        "metadata": {
            ...
        },
        "data": {
            ... 
        }
    }
}

If an event originates from a DynamoDB event, the new and old image will be added under data along with a JSON diff under metadata:

{
    "source": "my-source",
    "detail-type": "my-detail-type"
    ...,
    "detail": {
        "metadata": {
            "diff": {
                "Price": [3, 5]
            },
            "action": "update"
        },
        "data": {
            {
                "old": {
                    "Id": "123",
                    "Price": 3
                },
                "new": {
                    "Id": "123",
                    "Price": 5
                }
            }
        }
    }
}

The JSON diff will only be added if both old and new are assigend.

If old is null and new is assigned, then metadata.action will be set to create.

If new is null and old is assigned, then metadata.action will be set to delete.

Usage

npm install --save @mhlabs/events-client

const events = require("@mhlabs/events-client");
const client = new events.Client(eventBridgeClient, eventBusName, source);

All constructor arguments are optional and defaults to:

• eventBridgeClient: new AWS.EventBridgeClient()
• eventBusName: "default"
• source: `process.env.StackName

This is intended to run in AWS Lambda and will by default use the CloudFormation stack's name, as source.

To send a single event:

const eventDetail = { id: 123, value: 10 }
await client.send("my-detail-type", eventDetail);

To send multiple events. Max 10 per batch:

const eventDetail = [{ id: 123, value: 10 }, { id: 234, value: 15 }]
await client.send("my-detail-type", eventDetail);

To send DynamoDB events from a lambda trigger:

async function handler(dynamoDbEvent, context) {
    await client.send("my-detail-type", dynamoDbEvent);
}