I2JAV12 — is_a support in Java for local interfaces

With the recent adoption of the resolution to issue 4623 (support
is_a on local interfaces), we need to answer the question of how
is_a is implemented in Java. I would like to create a new
Java RTF issue for this, and propose a solution to hopefully start
some discussion on this issue.

Proposed solution:

Change org.omg.CORBA.LocalObject to an abstract class as follows:

abstract public class LocalObject implements org.omg.CORBA.Object {

...

abstract public String[] _ids() ;

public _is_a( String repository_id)
{
String[] ids = _ids() ;
for (int i=0; i<ids.length; i++)

return false ;
}
}

Then the IDL compiler generates a local implementation base class as follows:

class <typename>LocalBase extends org.omg.CORBA.LocalObject
implements <typename> {

private String[] _type_ids() =

public String[] _ids()

}

where _type_ids contains a list of repository IDs of the local
interface and all of its superinterfaces in order from most derived
to org.omg.CORBA.Object.

The implementer of a local interface then simply writes

class MyImpl extends <typename>LocalBase

and instantiates the local interface by calling

new MyImpl( ... ).

Note: a full proposed resolution to this issue should include a static
delegate for LocalObject, so that the implementation of _is_a and any
other non-trivial methods can be made pluggable in the JDK. I will raise
another issue for get_interface_def after we have an issue number for
this issue.

Incorporate the revised text, make corresponding changes in the standard source files, close