Hi Shreya,
The build-in eXist-db stores its files under WEB-INF/exist-data. However, note that those are the binary files used by the database itself.
If you'd like to get to the XML documents stored by Orbeon Forms in the database, the easiest way is to go through WebDAV: with your browser going to
http://localhost:8080/orbeon/exist/webdav//db/orbeon/g, using the 'admin' username, without password. Out of the box, however, this won't work, as you wouldn't want anyone to be able to access your database. So to make this work you need to disable that protection, and you do this by commenting out in your web.xml the <filter-mapping> for orbeon-exist-filter.
Alex
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