A method includes advertising a policy characterizing communication properties supported by a node. The policy may be distributed to another node in response to a request for the policy. Policy expressions in the policy include one or more assertions that may be grouped and related to each other in a plurality of ways. A system includes a policy generator for generating at least one policy characterizing properties of a node. A policy retriever retrieves a policy from another node and a message generator generates a message to the other node, wherein the message conforms to the policy from the other node.