The Policy API for C mandates that any resource be represented in a string format. Thus, resources on a web server must be represented as URLs. The Policy Service is then able to compare the resource string to the policy string and determine a relative relationship between the two. This relationship will be defined as one of the following:
exact pattern match
Exact pattern match is a special case where resources may be represented collectively as patterns. The information is abstracted from the Policy Service and the comparison operation must take a boolean parameter to trigger a pattern matched comparison. During the caching of policy information, the policy engine does not care about patterns, whereas during policy evaluation, the comparisons are pattern sensitive.