In the xforms model section of the form, you can define a submission, similar to the abstract code below:
<xforms:model schema="form.xform.xsd">
...
<xforms:submission id="fillvalues" method="get" action="http://127.0.0.1:8888/myrestservice" replace="instance" instance="myinstance">
<xforms:message ev:event="xforms-submit-error">...error message ...</xforms:message>
</xforms:submission>
...
</xforms:model>
You can then use this submission for example at load time, to fill values in your form:
<xforms:action ev:event="DOMActivate">
<xforms:send submission="fillvalues"/>
</xforms:action>
And the instance will be loaded with the needed data.
There is also a REST section
on the Orbeon website, for more information.
