StaticTopLevelPolicyElementEvaluator instantiation problem.

[miladamery]

Hi. i'm trying to create a custom policy provider. i need to use

@Value("classpath*:**/policies/**.xml)
private Resource[] resources;

and use those resources as files for policy providing. its a spring resource thing.
but meanwhile in the process i'm facing:

protected StaticTopLevelPolicyElementEvaluator getPolicy(String policyId,
			Optional<PolicyVersionPatterns> policyPolicyVersionPatterns) throws IndeterminateEvaluationException {
...
}

what i read at mongodb policy provider reference or CorRefPolicyProvider code i see a static class called PolicyEvaluators which is responsible for instantiating this. but this class is in core-pdp-engine and in wiki says that i should have core-pdp-api dependency. so my question is shall i go and implement my own PolicyEvaluator or i should use the one in core-pdp-engine to instantiate it?

[cdanger]

StaticTopLevelPolicyElementEvaluator is a very generic interface for a policy evaluator. The PolicyEvaluators#getInstance(...) methods are just some convenient ways to create such type of object from a XACML/XML-schema-derived Policy(Set), parsed with JAXB framework. If you indeed use XML/JAXB classes as input, then yes, it is a good idea to reuse PolicyEvaluators helper class; and in this case you can just replace core-pdp-api with core-pdp-engine as dependency in your POM, because core-pdp-engine already depends on core-pdp-api.

If you don't use XACML literally (you may use a JSON variant of your own or some kind of simplified policy format for convenience), or you are not using JAXB for XML-to-Java mapping, it may not be a good idea (not efficient) to use PolicyEvaluators as is.

In any case, you do not have to use PolicyEvaluators in all cases (it is just a helper class), and core-pdp-api is just the minimum required dependency to implement a PolicyProvider.

[miladamery]

thanks for answer. this helper class helps a lot. i'm going to reuse it.