Not really. You always have to have to use a service to "render" the XDP into a PDF. In the case of Designer it has this service embedded into it. If you use workbench, you would have to build an orchestration and use renderPDFForm to create a PDF from your XDP and save it to the file system. Once that's done, if could be as easy as invoking the service and just pass the name of the xdp from the repository to be converted and saved to the file system.
Remember that you can also open the XDP in Designer within Workbench.
Jasmin
