What do you mean by "back to my URL"? Is this going to be a fairly simple HTTP transaction, where your script will request a resource from this other server via HTTP, and that HTTP response will be an XML document? Or are you talking about initiating the construction of this XML document, and awaiting the other end to establish a TCP connection to you to deliver it? Will this latter response be via HTTP also (to your web server), or just a simple TCP data stream sent to some high numbered port? Will this "response connection" be over SSL?

I suspect and hope that you don't mean "back to my URL" the way it sounds, and that this XML reply will be delivered just as any other HTTP request/response would be. In this case, use LWP (or perhaps LWP::Simple) to do it. You will likely need to install an SSL library such as OpenSSL to make use of HTTPS URL's, which makes it a bit harder to do.