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diff --git a/docs/pap/pap.rst b/docs/pap/pap.rst index 964712e6..ff6aac51 100644 --- a/docs/pap/pap.rst +++ b/docs/pap/pap.rst @@ -21,6 +21,64 @@ PDP group to arbitrarily appear and disappear and for policy consistency across maintained. The PAP is responsible for controlling the state across the PDPs in a PDP group. The PAP interacts with the policy database and transfers policies to PDPs. +The unit of execution and scaling in the Policy Framework is a *PolicyImpl* entity. A *PolicyImpl* entity runs on a PDP. +As is explained above, a *PolicyImpl* entity is a *PolicyTypeImpl* implementation parameterized with a TOSCA *Policy*. + +.. image:: images/PolicyImplPDPSubGroup.svg + +In order to achieve horizontal scalability, we group the PDPs running instances of a given *PolicyImpl* entity logically +together into a *PDPSubGroup*. The number of PDPs in a *PDPSubGroup* can then be scaled up and down using Kubernetes. In +other words, all PDPs in a subgroup run the same *PolicyImpl*, that is the same policy template implementation (in +XACML, Drools, or APEX) with the same parameters. + +The figure above shows the layout of *PDPGroup* and *PDPSubGroup* entities. The figure shows examples of PDP groups for +Control Loop and Monitoring policies on the right. + +The health of PDPs is monitored by the PAP in order to alert operations teams managing policies. The PAP manages the life +cycle of policies running on PDPs. + +The table below shows the deployment methods in which *PolicyImpl* entities can be deployed to PDP Subgroups. + +========== =========================================== ============================== ================================== +**Method** **Description** **Advantages** **Disadvantages** +========== =========================================== ============================== ================================== +Cold The *PolicyImpl* (*PolicyTypeImpl* and No run time configuration Very restrictive, no run time + TOSCA *Policy*) are predeployed on the PDP. required and run time configuration of PDPs is possible. + PDP is fully configured and ready to administration is simple. + execute when started. + + PDPs register with the PAP when they + start, providing the *pdpGroup* they + have been preconfigured with. + +Warm The *PolicyTypeImpl* entity is predeployed The configuration, parameters, Administration and management is + on the PDP. A TOSCA *Policy* may be loaded and PDP group of PDPs may be required. The configuration and + at startup. The PDP may be configured or changed at run time by loading life cycle of the TOSCA policies + reconfigured with a new or updated TOSCA or updating a TOSCA *Policy* can change at run time and must be + *Policy* at run time. into the PDP. administered and managed. + + PDPs register with the PAP when they start, Support TOSCA *Policy* entity + providing the *pdpGroup* they have been life cycle managgement is + predeployed with if any. The PAP may update supported, allowing features + the TOSCA *Policy* on a PDP at any time such as *PolicyImpl* Safe Mode + after registration. and *PolicyImpl* retirement. + +Hot The *PolicyImpl* (*PolicyTypeImpl* and The policy logic, rules, Administration and management is + TOSCA *Policy*) are deployed at run time. configuration, parameters, and more complex. The *PolicyImpl* + The *PolicyImpl* (*PolicyTypeImpl* and PDP group of PDPs may be itself and its configuration and + TOSCA *Policy*) may be loaded at startup. changed at run time by loading life cycle as well as the life + The PDP may be configured or reconfigured or updating a TOSCA *Policy* cycle of the TOSCA policies can + with a new or updated *PolicyTypeImpl* and *PolicyTypeImpl* into the change at run time and must be + and/or TOSCA *Policy* at run time. PDP. administered and managed. + + PDPs register with the PAP when they Lifecycle management of TOSCA + start, providing the *pdpGroup* they have *Policy* entities and + been preconfigured with if any. The PAP may *PolicyTypeImpl* entites is + update the TOSCA *Policy* and supported, allowing features + *PolicyTypeImpl* on a PDP at any time after such as *PolicyImpl* Safe Mode + registration and *PolicyImpl* retirement. +========== =========================================== ============================== ================================== + 1 APIs ====== |