Issue: The JAXP+modules story is still a bit of a mess

[David M. Lloyd]

I'm not sure if this is just something that has not yet been gotten 
'round to, but the way JAXP loading works has become somewhat less 
convenient.

If you are a container author, and you need to supply your own global 
default JAXP implementation classes, your options are highly limited: 
you can rely on TCCL being set on every call to Xxxx.newFactory() (never 
going to happen 100% of the time in reality), or you can set the 
appropriate system properties and make your implementation visible from 
every class loader (something of the opposite of the kind of 
encapsulation that we have modules for).

Today we do the latter, along with some "redirect" implementations of 
all the major JAXP classes which allow the global default factory to be 
established or changed by suitably privileged code.  However, this 
solution is untenable when the JDK implementation classes cannot be 
accessed: the global default which is established by the JDK is now 
extremely difficult to reach through any other means!

The system property approach - really any approach to locating anything 
which involves a class name without some kind of context for locating 
that class (be it a module name or whatever) - is pretty outdated; it 
seems like it could be a good idea at this time to add methods to allow 
setting (maybe even on a one-time-only basis) a global 
Supplier<XxxFactory> for each JAXP type.  Is there any way this could be 
accomplished?

-- 
- DML