What are some books about SOA security?

 (SOA) allows different ways to develop applications by combining services. The main premise of SOA is to erase application boundaries and technology differences. As applications are opened up, how we can combine these services securely becomes an issue. Traditionally, security models have been hardcoded into applications and when capabilities of an application are opened up for use by other applications, the security models built into each application may not be good enough.