Hello Marc,
your thoughts a message before were right. That’s what I already did (2. solace_replyTo and solace_correlationId) and then I tried to get it on the backend with a function and a consumer, but I had no success to get the response from the function that should call a SOAP service. But now I recognized that you do it already with the Microgateway. I tried to configure it this way - a link I received from @Hong - and it worked great. But I am asking myself, if I loose the normal messaging possibilities with Cloud Streams with the Microgateway setting. Do I have to install then something else? If my backend webservice is behind a firewall, does it make sence to opend special ports also or is it enough to open the port for the backend service. I will also try your second solution as soon as possible. Thanks a lot for your help!!!