Lambda function AWS

To create a Lambda function that listens to changes in a hub for connection status and then triggers a change in DynamoDB, you'll need to write a function that integrates with AWS services, such as Lambda, DynamoDB, and possibly others depending on your exact requirements. Here's a general outline of how you can set this up:

1. AWS Lambda Function: You will create a Lambda function in Node.js, which will be triggered by the event you are listening to in the hub.
2. Event Source: Determine the source of your events. If these are AWS events, you might use another AWS service like SNS (Simple Notification Service) or EventBridge to trigger your Lambda function.
3. AWS SDK: Use the AWS SDK for Node.js within your Lambda function to interact with DynamoDB.
4. Lambda Execution Role: Ensure your Lambda function has an execution role with permissions to access DynamoDB and any other AWS services it needs to interact with.
5. DynamoDB: Setup a DynamoDB table to record the connection status changes.

Here's a basic example of what the Lambda function code might look like in Node.js:

const AWS = require('aws-sdk');
 const dynamoDB = new AWS.DynamoDB.DocumentClient(); 
exports.handler = async (event) => { 
console.log("Received event:", JSON.stringify(event, null, 2)); 
// Extract connection state from the event 
const connectionState = event.connectionState;
 // Define DynamoDB update parameters 
const params = { TableName: "YourDynamoDBTableName", Key: { "YourPrimaryKey": "YourKeyValue" }, UpdateExpression: "set connectionState = :c", ExpressionAttributeValues: { ":c": connectionState }, ReturnValues: "UPDATED_NEW" }; 
try { 
// Update DynamoDB 
const data = await dynamoDB.update(params).promise(); 
console.log("Update succeeded:", JSON.stringify(data, null, 2)); 
} 
catch (error) { 
console.error("Update failed:", JSON.stringify(error, null, 2)); 
throw error; } };        

In this example:

• The Lambda function is triggered by an event (which you will need to define based on your architecture).
• It then updates a DynamoDB table with the new connection state.
• You'll need to replace "YourDynamoDBTableName" and "YourPrimaryKey" with your specific table and key names.
• Also, ensure that event.connectionState correctly corresponds to the structure of the event your Lambda function will receive.