A BizTalk orchestration can be called as a service from an outside application. By exposing it as a service, you are able to call it from the application, as you would normally do with other web services. Exposed orchestrations supporting a generic process can be reused within your enterprise. By exposing orchestrations, you can take advantage of core BizTalk capabilities, such as error handling, document tracking, and integration into downstream BizTalk via the publish/subscribe architecture. From a service-oriented standpoint, you can extend outside your BizTalk environment and support creation of composite applications.