There is no productized way at the moment to have a process take an XDP and render it to HTML5 to return to the user.
The closest thing at the moment can be done if you have the Process Management Module. If so you can achieve this functionality as part of a human-centric workflow where you are assigning work items to users. You would use the AssignTask operation and point the Presentation and Data' Section application asset property to an XDP. The default render used by this operation behind the scenes can generate an HTML5 rendering if the call is coming from a mobile device or PDF if from a desktop.
If you need to render an XDP directly to HTML5 for an end-user that is not part of any business process then you need to do one of two things:
1. Have LiveCycle Forms Portal version that gives you acces to API or in the fall CQ components that you can use from your customer facing web page to interface with the LiveCycle Content repository to request a form be rendered as HTML.
2. Have the base Mobile Forms and then do one of two things...
i) Manufacture the REST based url that will call mobile forms and pass it the xdp you want to render to HTML OR
ii) If you do not know how to do that you could use the Form Manager application as a form designer. Make use of its Preview functionality to preview HTML and then copy the URL as a quick way to see how it is structured
If you really want that as part of building a process within Workbench at the moement you would have to build a custom component.
