ABAC, Attribute Based Access Control - Can You Do Your $500 Expense Approval in This?

Common expression language is a Google open source way of defining essentially Boolean logic. You can write that out in pretty much prose because it's a very structured and clean way of defining it. And then that's your policy files. One thing you need to be careful of when you define as business logic is making sure you've caught sort of all the edge cases. So one of the best tooling that's available is you can actually write unit tests against server's policies.