Well, I was confirming that you could leverage spring xd in a portlet.
That said, you can use spring with any portlet frameworks. It's automatically available for Liferay MVC or Spring MVC portlets, you can pull in spring in JSF portlets, you can leverage it in Vaadin and probably many other frameworks.
As far as how to integrate, well the quick answer is "sure" because you can work up a portlet to invoke spring xd to get the data, the problem is that there are going to be many more ways to do that incorrectly than not.
Ideally you retrieve and manipulate data during an action and put it into a form to display during render. First render is a special case you'd need to account for, but you don't want to retrieve at every render because that gets invoked every time the portal refreshes the page (unless, of course, this satisfies some requirement).
