What is JAXR? JAXR, or the Java API for XML Registries (JSR 93), is a way of interacting with various kinds of registries. It is meant to be an abstraction so that you can switch out different registry implementations (UDDI, ebXML, and so on) without having having to change your query code.

JAXR is notable in terms of JBoss ESB because it is used to query the registry. JBoss ESB uses Scout, the Apache JAXR implementation, on top of UDDI. For the purposes of this book, you should just know that this is an added layer of abstraction.