public interface ServiceRef
This proxy ensures that services won't have to be known (i.e. their
classes don't have to be instantiated), to do the work within the
mechanisms of the services framework. This allows the classes to be
lazily loaded based on when the client actually needs to use them.
At the time they're needed, services will be constructed from
ServiceRef's using a 2 argument constructor, with the service file URL,
and an enumeration of non comment items found in the service file.
Therefore all service developers must provide this constructor.
If the service developer wishes, the service file item enumeration
may be used to access the remaining content from the service file.
But once the constructor returns, all references to it should no longer
be held by the service. If information is needed then it should be
copied from it before returning from the constructor.