What is the way to go to validate a JavaRosa xml file ? Is there an official XSD or DTD ?
For XForms itself, you can use W3C's XForms-11-Schema.xsd.
For JavaRosa form submissions, you can use their OpenRosaMetaDataSchema:
There are two types of metadata in a form submission. The first provides metadata about the identity and version of the XForm used to create the data being submitted. The second captures useful information about the submission itself.