todo: For ajp, add prefix in shib2.xml,     add permitted pattern in 8009 connector in server.xml

See: https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2067400159/JavaHowTo

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Very Basic Overview

IdP (Identity Provider): A web-based system that can authenticate a user on behalf of another system called SP (for Service Provider).

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