Unnamed module and duplicate package

[Alan Bateman]

On 11/03/2016 10:04, Neil Bartlett wrote:
> :
>
> Whatever the motivation, I referred to this package as “broken” because it has caused a great many problems for OSGi users. Applications that import the javax.transaction package may encounter NoClassDefFoundError due to the missing types if they wire to the platform export. The most commonly employed practical solution is to add back those types with the application ClassLoader.
Deploying the classes on the class path (application class loader) meant 
some types in javax.transaction defined to the boot loader (because of 
delegation) and some to the application class loader. A sad state of 
affairs that would not have worked if there had been any reliance on 
anything package private.

Going forward then it requires deploying the EE version of the 
java.transaction module on the upgrade module path.


>
> A properly constructed set of OSGi bundles *should* never throw NoClassDefFoundError or ClassNotFoundException, and I would hope this will also be the case in Jigsaw.
If it compiles then it should run so I would not expect 
NoClassDefFoundError. ClassNotFoundException hints of Class.forName and 
core reflection usage so the compiler cannot help.


> :
> Would this include the javax.sql.* packages? Since javax.sql exposes XAResource via its method signatures, it would be necessary for the classloader of javax.sql to have visibility of those types also.
>
Yes, except the types in the javax.sql.rowset package as that is a 
different module.

The definition for both the java.sql and java.sql.rowset modules can be 
found here:
http://cr.openjdk.java.net/~mr/jigsaw/ea/module-summary.html#java.sql

or if you have the EA builds then `java 
-listmods:java.sql,java.sql.rowset` will describe these modules.

In terms of visibility then both modules are currently defined to the 
boot loader and hence their types are visible via any of the built-in 
class loaders. We are on a mission to move non-core modules out of the 
boot loader so that they don't have all permissions by default. Easier 
said that done of course but we have already moved all the modules 
shared with EE so that they can be upgraded by app servers.

I hope we can move java.sql.rowset module, I don't know about java.sql 
yet. There is a small spec change needed to do the latter because 
currently only the boot loader can defined java.* types (one of the 
comments in your mail suggests you are aware of this detail).

-Alan