Is the SNS necessary in your design?

[tomaszdudek7]

Hi there. I'm just wondering if the SNS as the "decoupling" mechanism is necessary and/or if there was a specific requirement or reasoning behind it.

Your flow of getting a response from a model is as follows:

1. front-end connects to a websocket - which, under the hood, invokes the publisher Lambda - but it doesn't do much due to route_key being equal to $connect
2. then, front-end sends the user prompt to the open websocket (

   bedrock-claude-chat/frontend/src/hooks/usePostMessageStreaming.ts

   Line 25 in c2eec81

   ws.send(JSON.stringify({ ...input, token }));

   ) - it also triggers the same publisher Lambda. However, this time, it actually pushes the prompt forward to the SNS because the route_key is different.
3. now, the SNS invokes the websocket Lambda, which streams the response back to the websocket (https://github.com/aws-samples/bedrock-claude-chat/blob/main/backend/app/websocket.py#L77)

However, if (instead of being SNS consumer) your websocket Lambda was just a different route on the WS API gateway (lets call it /invoke), then the flow could look as follows:

1. front-end connects to a websocket - which, under the hood, invokes the publisher Lambda - but it doesn't do much due to route_key being equal to $connect
2. front-end sends the user prompt to the open websocket as an action /invoke - it triggers the websocket Lambda

Voila, you no longer need the SNS and it still works the same way.

Am I missing something (could be totally wrong above of course)? Is the SNS here necessary? Does it provide any additional value over this alternative method that I've described which would simplify the design?

Other than that - great work. Thanks for providing this excellent blueprint!

[ctodd]

Tomaz, check out the Readme under Architecture. I just happened to read this myself and was wondering the same thing. :-)

[Amazon SNS]: Used to decouple streaming calls between API Gateway and Bedrock because streaming responses can take over 30 seconds in total, exceeding the limitations of HTTP integration (See quota).

[statefb]

@tomaszdudek7
Thank you for your suggestion. We re-verified the behavior of http integration and confirmed that lambda can continue to send message to websocket connection after 30 sec passed although the message Endpoint request timed out sent. So I believe that we can simplify the architecture with front-end implementation which ignore the message saying timed out. We'll modify when we have time (PR is also welcome), thank you!

[tomaszdudek7]

@ctodd Yes, but my point was that SNS is not even required here, as confirmed in the comment above.