Policy enables you to verify the runtime behavior of a service in a declarative manner, free of the service implementation and binding details. For example, if you require a service to always participate in a global transaction only, you can add logic to your service implementation which checks the current transaction state, associates with an active global transaction, and handles error cases. Also, ensure that the gateway used to expose the service is transactional and that it propagates the transaction to the service implementation.

The SwitchYard runtime reads these policy definitions during deployment and enforces them on a per-message basis as services are invoked.