WebSocket APIs - AWS Serverless

WebSocket APIs allow for two-way communication between clients and servers over a single, long-lived connection. This is particularly useful for applications that require real-time updates, such as chat applications, gaming, and live notifications.

• WebSocket Protocol: A protocol providing full-duplex communication channels over a single TCP connection.
• AWS API Gateway: A fully managed service that makes it easy to create, publish, maintain, monitor, and secure WebSocket APIs.
• Connections: Each WebSocket client connection is managed and maintained by the API Gateway, allowing for easy scaling and handling of multiple connections.

To set up a WebSocket API in AWS, follow these steps:

1. Log in to the AWS Management Console.
2. Navigate to API Gateway and select "Create API".
3. Choose "WebSocket API" and provide a name for your API.
4. Define the route selection expression (e.g., "$request.body.action").
5. Create routes for different actions, like connect, disconnect, and default.
6. Integrate routes with Lambda functions or other AWS services.
7. Deploy your API by creating a new stage.

Below is a simple example of a Lambda function that handles WebSocket connections:

    const AWS = require('aws-sdk');
    const apigatewaymanagementapi = new AWS.ApiGatewayManagementApi({
        endpoint: process.env.WEBSOCKET_API_ENDPOINT
    });

    exports.handler = async (event) => {
        const connectionId = event.requestContext.connectionId;
        const message = JSON.parse(event.body).message;

        try {
            await apigatewaymanagementapi.postToConnection({ 
                ConnectionId: connectionId, 
                Data: message 
            }).promise();
            return { statusCode: 200, body: 'Message sent.' };
        } catch (err) {
            return { statusCode: 500, body: 'Failed to send message.' };
        }
    };
                

• Implement proper error handling to manage connection issues.
• Use CloudWatch for monitoring WebSocket connections and traffic.
• Scale your Lambda functions to handle bursts of traffic effectively.
• Secure your WebSocket API using IAM roles and policies.