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The resolution process behaves as though an assertion containing a subject identifier (e.g. a persistentID) was received from the entity identified by the various parameters, and then performs a call to the resolver equivalent to what would be performed if no attributes were initially received. Suitably manipulated, this makes it possible to generate arbitary arbitrary attribute queries to systems for which metadata is available. One use case is to retrieve user attributes from a user's Identity Provider without the user's involvement, provided the SP has for example the users persistentID Name ID.
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