Virtually all SOA systems are heterogeneous composite applications. They span platforms, departments and corporate boundaries. They include both standards-based Web services and other components such as mainframes and packaged applications. And their interactions are facilitated by SOAP and XML Web services, messaging systems such as JMS and MQ, database calls, RMI and EJB applications.
With so many layers of components coupled together, SOA transactions spanning multiple systems and services might "disappear" beyond a certain point in their flows. This makes it a tremendous challenge to provide visibility into the business transactions that are flowing through these SOA systems as well as isolating and resolving issues as they develop.