View source for RegisterCallback

== Description ==
Registers an instance of the callback interface for receiving events related to field devices and jobs. Each user may register only once, if more than one callback interface must be registered, a user for each must be created in the NADS system. 

As part of the registration process, getVersion will be called on the interface to ensure that the version is supported and the interface is up. If this test fails, an failure will be returned by this method.