SitePub is tied to TeamSite, and so the internal JBoss (Tomcat, if you're pre-7.1) is the only app server that can be used with it. If you want to push your SitePub-authored pages to your ATG app server and send your users there to preview, you'd need to set up a LiveSite Runtime in ATG. Note however, that any components you design with externals that somehow depend on ATG features wouldn't render the same (if at all) in SitePub's wysiwyg edit mode. But then if you're using externals for runtime display of data, you'd also need LiveSite as your production rendering engine.What's not clear to me is how you plan on using SitePub. Presumably, if you're deploying files to an app server, you've got some dynamic logic in those pages. SitePub (without LiveSite) can only be used to generate static HTML, which makes me wonder how you'd use that output in conjunction with your app server.