Hi folks, There have been requests for triggering a Pulsar Function just like one can curl an AWS Lambda. There can be several modes using different mechanisms that can be supported. Just wanted to get community feedback around this. The idea is that one can issue a curl command with payload to a Pulsar Function running inside a Pulsar cluster and have the function work on the payload. The output of the function, if any, should be the response of the curl command. There are several considerations 1. Since Pulsar Functions consume from a topic, should we publish the message to the incoming topic. What if a function consumes from multiple input topics. In that case which topics should we publish on? Also note that publishing on input topic will also affect other consumers beside the function in consideration. 2. What is the side-affects of running functions this way. For example if they modify any counters, that would be globally seen. Is this reasonable behavior? What about any outputs being published to output topic? 3. What is the best mechanism to implement such a functionality? If side-effects are ok, then publish/consume is probably the easiest way to implement it. Alternatively one can send the payload via grpc from the brokers to the function instance to have it triggered. The state side-effects concerns still exist in this scenario.
Any other concerns? Feedback is welcome. Thanks!
