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Most of these components are some variation on a XACML finder module, which is a part of the original Sun engine API. The JBoss PDP implementation adds new options for wiring finder modules, via configuration of custom locator classes. In many cases the locator class extends the corresponding Sun finder module. For example the ResourceLocator extends ResourceFinderModule.
This is helpful reading for writing a finder:
http://sunxacml.sourceforge.net/guide.html#extending-finder
PolicyFinderModule (w/PolicyLocator for JBossPDP configuration)
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