- Policy Enforcement Point (PEP): The system entity that performs access control by making decision requests and enforcing authorization decisions. Basically this is the entity that sends the XACML request to the Policy Decision Point (PDP) and receives an authorization decision.
- Policy Decision Point (PDP): The system entity that evaluates an applicable policy and returns an authorization decision.
- Policy Information Point (PIP): The system entity that acts as a source of attribute values. Basically if there are missing attributes in the XACML request that is sent by PEP, PIP would find them for the PDP to evaluate the policy.
- Policy Administration Point (PAP): The system entity that creates a policy or policy set and manages them.
XACML engine architecture
The WSO2 Identity Server is a major player in the XACML and open source world. The Identity Server supports XACML 3.0, which is based on Balana XACML implementation. As the source code, distribution and documentation are available for free, it is possible to analyze and understand the architecture behind it. This section provides some information regarding the architecture of the XACML engine (or the entitlement engine) of the WSO2 Identity Server.