jar installation standards

Tue Feb 26 11:39:00 GMT 2002

Bryce McKinlay wrote:
> I think this is the best approach, due to its simplicity and 
> compatibility with existing behaviour of the JDK. .jars do not really 
> support versioning, and given the binary compatibility reqirements, 
> typically do not suffer from the same versioning problems as shared 
> libraries.

 From the discussion on the debian-java list it appears a lot of people
disagree. Supposedly many people have had problems because some library
or application needs a specific version of some other jar. Various
people emphatically did not want an automatic "put everything in the
classpath" extension mechanism, because they feel they need to precisely
control which version of which jar gets linked in. I do think we
need such an extension mechanism, but it needs to support multiple
versions of jars.
Using the latest version of a jar does not work. For example each
version of the servlet interfaces has new methods, so classes that
implement the interfaces will often only work against a specific
version. (Thank you Sun.)
So take it as given that we will need to install multiple versions
of various jara at the same time. We can have an "ext" directory
that contains symlinks without versions. E.g.
$prefix/java contains PACKAGE-VERSION.jar
$prefix/java-ext contains PACKAGE.jar which is s symlink to
../java/PACKAGE-VERSION.jar.
-- 
	--Per Bothner
per@bothner.com http://www.bothner.com/per/