Serverless compute targets (e.g. AWS lambda) that initiate network connections have no built-in way of offloading that connection management in the case of long polling, websockets, http2, etc.
This means that a reactive lambda that makes an outbound network connection spends most of its execution time in an endless IO wait.
AMZN APIGW can take incoming websocket connections and translate those requests into a request/response model. This is desirable! What would be great is allowing that for outbound connections as well.
Currently the only way to do this is with an out of band proxy (typically nginx).