Calum Shaw-Mackay wrote:
Interesting.
Perhaps Marshalled object instances should also be decorated.
Yeah you'd need somewhere to start, and as I mentioned below about
transparency, you'd possibly need a
DEFAULT or CURRENT version, because if you're bringing in an object
foreign to the VM, and you're using
static analysis, you'd need to have the bytecodes available to
actually compare it against, having an initial
version identifier would give it a head start in terms of performance,
and you don't want to brute-force
hammer the network bringing in multiple dl jars, for a class that has
not been seen in any version in this JVM session
I think the more 'hints' you could provide to the classloader, through
either compatible version ranges or soft links
the better.
Whichever way you want to tackle this, you'll need it to be as
transparent a mechanism as possible so that service/bundles/clients
that don;t specify versions work as they always have,
Thanks Calum, good point, when version metadata doesn't exist, the results
from Static Analysis alone could be utilised to find API compatible import
packages. I guess classes lacking version metadata could be treated as
version 0. If someone later decides to add version metadata, perhaps after
correcting a bug, the higher versioned package would be preferred, provided
it remains API compatible and shares the same fully qualified package name.
Yeah I'd say a DEFAULT (i.e. 0, although that itself may go through
changes in time) and perhaps symlink-type versioning including a
CURRENT.
I could use the class file modification dates from the jar files, so
where more than one package of the same name exists, where both have an
API that satisfy the dependency requirements, where version metadata
isn't provided, the later modified file is preferred.
In a way, what you don't want is to break compatibility unnecessarily.
Calum
