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The IdP's Attribute Filtering Engine is a policy engine that determines what information, expressed as attributes as described in the Attribute Resolver Design document, is released by the IdP. This gives the author of the filtering policies the power to permit or deny the release of information regardless of what a requester may have asked for.
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Parameters to the Attribute Filter operation are provided by the AttributeFilterContext which is also where the resulting filtered attributed are stored.. In addtion, the AttributeFilterWorkContext is used as work space for the attribute filtering process; this context is entirely private to the specific implementation of attribute filtering.
Programming Guide to Attribute Filtering
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