• websocket.py : Main program source file
• lambda_util.py : Utility functions to manage AWS Lambda functions
• websocket_connect.py : AWS Lambda function to implement the WebSocket $connect route
• websocket_disconnect.py : AWS Lambda function to implement the WebSocket $disconnect route
• websocket_send_msg.py : AWS Lambda function to implement the WebSocket sendmsg custom route (Python)
• websocket_send_msg.js : AWS Lambda function to implement the WebSocket sendmsg custom route (JavaScript)

• API Gateway WebSocket API
• AWS Lambda functions for the WebSocket $connect and $disconnect routes and a WebSocket sendmsg custom route
• AWS Identity and Access Management (IAM) role and policy for the AWS Lambda functions
• Amazon DynamoDB table to store connection IDs and user names

• Install Python 3.x.
• Install the AWS SDK for Python boto3. Instructions are at https://github.com/boto/boto3.
• Install the AWS CLI (Command Line Interface). Instructions are at https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-install.html.
• Configure the AWS CLI. Instructions are at https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html.

To create the WebSocket infrastructure:

python websocket.py 

To delete the WebSocket infrastructure:

python websocket.py -d OR python websocket.py --delete 

To use the WebSocket Chat Program:

1. Download and install Node.js from https://nodejs.org. Node.js includes the npm package manager.

2. Use npm to globally install wscat.

    npm install -g wscat 

3. When the WebSocket infrastructure is created, the WebSocket WSS address is output. Copy the output WebSocket WSS address and enter it on the wscat command line to open a WebSocket connection. Open multiple connections by running wscat in separate terminal windows.

    wscat -c WSS_ADDRESS 

   Example command line:

    wscat -c wss://123abc456def.execute-api.us-west-2.amazonaws.com/dev 

   Optional: Specify a user name as a query parameter in the WSS address (Used by the Python version of websocket_send_msg.py)

    wscat -c wss://123abc456def.execute-api.us-west-2.amazonaws.com/dev?name=Steven 

4. Send a chat message to all open connections:

    {"action": "sendmsg", "msg": "Enter message text here"} 

   The "action": "sendmsg" pair invokes the WebSocket sendmsg custom route.

   The "msg": "Enter message text here" pair specifies the message text to send.

5. To close the WebSocket connection:

    <Ctrl-C>