model.xml

<xf:model
    xmlns:xf="http://www.w3.org/2002/xforms"
    xmlns:xxf="http://orbeon.org/oxf/xml/xforms"
    xmlns:frf="java:org.orbeon.oxf.fr.FormRunner">

    <xf:instance id="master-data-instance"><dummy/></xf:instance>

    <xf:send
        event="fr-data-ready"
        if="    normalize-space(xxf:get-request-parameter('master-form'))
            and normalize-space(xxf:get-request-parameter('master-document'))"
        submission="get-master-data-submission"/>

    <xf:submission
        id="get-master-data-submission"
        method="get"
        serialization="none"
        replace="instance"
        instance="master-data-instance"
        action="/fr/service/persistence/crud/worthit/{xxf:get-request-parameter('master-form')}/data/{xxf:get-request-parameter('master-document')}/data.xml"/>

    <xf:message event="xforms-submit-done" target="get-master-data-submission">Loaded master form data</xf:message>

    <xf:action event="xforms-submit-error" target="get-master-data-submission" type="xpath">
        frf:sendError((event('response-status-code'), 500)[1])
    </xf:action>

</xf:model>