The XML REST (eXtensible Markup Language REpresentational State Transfer) will be the secondary end point and will be developed at around the same time as the JSON end point. The XML Rest end point would most likely be of the form: www.example.com/rest.

An example of an XML REST message would be:

<menu id="file" value="File">
<menuitem value="New" onclick="CreateNewDoc()" />
<menuitem value="Open" onclick="OpenDoc()" />
<menuitem value="Close" onclick="CloseDoc()" />

This would be most likely used by the Drupal modules.