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From James Duncan Davidson <james.david...@eng.sun.com>
Subject Re: [Proposal] Guidlines for package distribution of Java projects:like XML file being read by class
Date Thu, 25 Nov 1999 00:21:19 GMT
Mike Pogue wrote:
> I think we really need both ways:
> 
> a) at runtime, there must be a way to query the version string, AND

Suggestion for this (at least for the Java side):

	1) Use the version info in the manifest.mf format
	2) Have a Version.java in the base package that would
		a) on 1.2+ use java.lang.Package
		b) on 1.1 getResource("META-INF/manfiest.mf") and parse

For those that aren't "up" on the 1.2 package versioning spec, look at:

http://webmirror.eng/products/jdk/1.2/docs/guide/versioning/index.html

More explicitly, here's a sample manifest that shows the kind of version
information that is exposed:

	  Manifest-version: 1.0
          Name: java/util/
          Specification-Title: Java Utility Classes 
          Specification-Version: 1.2
          Specification-Vendor: Sun Microsystems Inc. 
          Implementation-Title: java.util
          Implementation-Version: build57 
          Implementation-Vendor: SunMicrosystems. Inc.

> b) at install time, it's nice to be able to look at a JAR, and determine
> what version it is, without running a program.

Yep. The files can be named xerces-1.0.1.jar etc. Hmmm. Maybe in Ant
there can be an option to auto version the generated file based on the
manifest. I'll take a look at that tonight as that might be pretty cool
irregardless of this discussion.

On my system, use I keep a lot of utility jars around with just this
kind of format and just shift my classpath accordingly. Now that the new
JDK load all jars in the /lib/ext directory, I just use that and keep a
backlog of older jars.

-- 
James Davidson                                     duncan@eng.sun.com 
Java + XML / Portable Code + Portable Data                 !try; do()

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