The BRE is host agnostic in that it can be hosted in any process, be it BizTalk or a custom application. BizTalk is the natural host and provides deep integration both with the runtime and administration tools.
Although rehostable, the BRE is licensed along with BizTalk Server. Licensing it for use outside of BizTalk might be impractical because of licensing costs. However, using the Rules API, which we cover throughout this chapter, you can invoke rules in any application. Note that the Policy class does, however, require the Rules Engine Update Service to be running.