Enforcing complex policies that span organizational domains is an open challenge. Current work on SOA policy enforcement splits security in logical components that can be distributed across domains, but does not offer any concrete solution to integrate this security functionality so that it works across security services for organization-wide policies. In this paper, we propose xESB, an enhanced version of an Enterprise Message Bus (ESB), where we monitor and enforce preventive and reactive policies, both for access control and usage control policies, and both inside one domain and between domains. In addition, we introduce indicators that help SOA administrators assess the effectiveness of their policies. Our performance measurements show that policy enforcement at the ESB level comes with only moderate penalties.