Filter Data based on a field

[HoustonLucifer]

HI all, i am new to infopath sp1. I have an XML file as the Datasource for
one of the fields (field1) on the form. I have the same XML file as a
datasource for a different field (field2) on the form. Based on the value
chosen in field1, i want to filter the data in field2. How could i do this?
Based on the XML below when the user selects "TestApp1" in field1 i would
like to show two roles in field2 (Test APP1 Role1, Test APP1 Role2)

XML looks like below.
<XMLNS...>
<Root>
<Application name="TestApp1">
<Role>Test APP1 Role1</Role>
<Role>Test APP1 Role2</Role>
</Application>
<Application name="TestApp2">
<Role>Test APP2 Role1</Role>
<Role>Test APP2 Role2</Role>
</Application>
</Root>

Thanks

 

[Houston Lucifer]

Thanks