HTTPS utility called via Remote Invoke

This is sort of a 2-part topic.

I’ve been working on a proof-of-concept that involves uploading a file to a non-webMethods partner. The upload needs to be via HTTPS with uid/pwd authentication. Within the partners website I must navigate from login page, to options page, to the upload page in that order. I have not been able to accomplish anything other than the login via the pub.client.http service. It seems that successive calls of the http service within a flow don’t really produce a ‘session’ which I would need to go from page to page. It would seem like each call is kind of an open-close type of thing. Is this correct?

Now I have been able to accomplish the task via a java API outside of webMethods that I think I could move into a java service. The issue now becomes our architecture:

IS 4.6 (Production) -> | Firewall -> | IS 4.6 (DMZ) -> | Proxy

I need to go out through the proxy in the DMZ and the IS 4.6 Production must initiate the connection to IS 4.6 in the DMZ. I could put my java service on the IS in the DMZ and do a remote invoke, but the code would contain too much business logic (possibly along with uid/pwd). I need more of a utility service in the DMZ that can be utilized by many different solutions that need to make HTTPS calls. In other words, I need some type of service that is more or less a ‘pass-though’ of the HTTPS call so that I achieve the goal of going out the IS in the DMZ. Is it possible to do something like this? I’m not even sure where to start. Thanks