splitting xml file

I have to split an xml file into 3, choosing based on the value of one node; example:
<root>
<module>
.
.
<type>a</type>
.
</module>
<module>
.
.
<type>a</type>
.
</module>
<module>
.
.
<type>b</type>
.
</module>
.
.
.
</root>

i need to put al modules of type a in one xml, all of type b in another one

i'm inside a jsp based web app, and parsing with org.w3c.dom

anyone has sample code or some hints for me?

tnx in advance