Soap in node.js: necessary to call createClient at each request?

For a project we're working on, we're obliged to use a SOAP service inside a node server using express. I am using the npm soap package for it.

I am new to SOAP and it is not yet clear to me if the SOAP client needs to be created using createClient only once during start-up of the server, or if it needs to be created at each SOAP request. In other words, do I need to bind the SOAP client to the express app or do I just create a client at every request? The second approach is much simpler to implement, but I'm wondering if it can cause instabilities when multiple requests are made constantly? The relevant project can become quite large in a few months time, so I want to be sure this won't cause any downtimes if it does.

via user2416984