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ServiceMix is also fully integrated into Apache Geronimo to integrate JBI functionlity into Apache's J2EE container. This allows Apache Geronimo to hot-deploy any JBI component or service using its standard deployment tooling (JSR 77/88 compliant).
Also ServiceMix contains a number of WS-* implementations built on JBI, such as WS Notification.
Having said all that though; ServiceMix has full support for Mule; so if you already have an investment in some Mule configuration or code, you can reuse it inside ServiceMix along with any other JBI components.