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From "David Bosschaert (JIRA)" <j...@apache.org>
Subject [jira] Commented: (ZOOKEEPER-425) Add OSGi metadata to zookeeper.jar
Date Wed, 25 Nov 2009 10:15:39 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12782351#action_12782351
] 

David Bosschaert commented on ZOOKEEPER-425:
--------------------------------------------

Hi Patrick,

You can already use this as-is in Felix or Equinox (or any other OSGi container). The value
that the metadata in the buildxml.patch provides is that it exports (and imports) packages
the OSGi way, which means that you can build a zookeeper client in its own bundle that pulls
in the zookeeper classes using OSGi dependency management.

Here's a quick example of how to use it (using Felix 2.0.0):
{code}.../felix-framework-2.0.0>java -jar bin/felix.jar

Welcome to Felix
================

-> start http://www.springsource.com/repository/app/bundle/version/download?name=com.springsource.org.apache.log4j&version=1.2.15&type=binary
Bundle ID: 4
-> start file:///.../zookeeper/build/zookeeper-3.3.0.jar
-> ps
START LEVEL 1
   ID   State         Level  Name
[   0] [Active     ] [    0] System Bundle (2.0.0)
[   1] [Active     ] [    1] Apache Felix Bundle Repository (1.4.1)
[   2] [Active     ] [    1] Apache Felix Shell Service (1.4.0)
[   3] [Active     ] [    1] Apache Felix Shell TUI (1.4.0)
[   4] [Active     ] [    1] Apache Log4J (1.2.15)
[   5] [Active     ] [    1] ZooKeeper Bundle (3.3.0)

-> inspect package requirement 5
org.apache.hadoop.zookeeper [5] imports packages:
-------------------------------------------------
org.osgi.framework; version=1.5.0 -> org.apache.felix.framework [0]
org.osgi.util.tracker; version=1.4.0 -> org.apache.felix.framework [0]
javax.management; version=1.6.0 -> org.apache.felix.framework [0]
org.apache.log4j; version=1.2.15 -> com.springsource.org.apache.log4j [4]

-> inspect package capability 5
org.apache.hadoop.zookeeper [5] exports packages:
-------------------------------------------------
org.apache.zookeeper; version=3.3.0
org.apache.zookeeper.data; version=3.3.0
org.apache.zookeeper.version; version=3.3.0
org.apache.zookeeper.server; version=3.3.0
org.apache.zookeeper.server.quorum; version=3.3.0
{code}
As you can see the Log4J dependency is provided through a Log4J bundle. I'm using one straight
from the SpringSource bundle repository (the SpringSource guys have turned many libraries
into OSGi bundles), but you may also be able to find a Log4J bundle elsewhere.
After installing the Zookeeper Bundle (the jar is now also an OSGi bundle) you can see that
it uses OSGi imports to satisfy its dependencies (e.g. it links to bundle 4 for its log4j
imports) and it exports the zookeeper packages. The way to use them in OSGi-based clients
is simply through imports (as [here|http://svn.apache.org/repos/asf/cxf/dosgi/trunk/discovery/distributed/cxf-discovery/src/main/java/org/apache/cxf/dosgi/discovery/zookeeper/FindInZooKeeperCustomizer.java]),
but additionally the client bundle will have Import-Package statements for the zookeeper packages
in its manifest.


> Add OSGi metadata to zookeeper.jar
> ----------------------------------
>
>                 Key: ZOOKEEPER-425
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-425
>             Project: Zookeeper
>          Issue Type: Improvement
>          Components: build
>            Reporter: David Bosschaert
>            Assignee: David Bosschaert
>             Fix For: 3.3.0
>
>         Attachments: buildxmlpatch.patch, MANIFEST.MF, zk_patch3.patch
>
>
> After adding OSGi metadata to zookeeper.jar it can be used as both an OSGi bundle as
well as an ordinary jar file. 
> In the CXF/DOSGi project the buildsystem does this using the maven-bundle-plugin: http://svn.apache.org/repos/asf/cxf/dosgi/trunk/discovery/distributed/zookeeper-wrapper/pom.xml
> The MANIFEST.MF generated by maven-bundle-plugin is attached to this bug, this works
for the CXF/DOSGi project.
> If your buildsystem isn't using maven, I would advise to use bnd (http://www.aqute.biz/Code/Bnd).
BND defines its own ant task in which you should be able to use more or less the same instructions
as were used in maven:
> <instructions>
>   <Bundle-Name>ZooKeeper bundle</Bundle-Name>
>   <Bundle-Description>This bundle contains the ZooKeeper library</Bundle-Description>
>   <Bundle-SymbolicName>org.apache.hadoop.zookeeper</Bundle-SymbolicName>
>   <Bundle-Version>3.1.1</Bundle-Version>
>   <Import-Package>*</Import-Package>
>   <Export-Package>*;version=3.1.1</Export-Package>
> </instructions>
> Oh and one other thing. Is it really necessary to put the source code in the Jar file
too? I would put that in a separate source distribution :)
> See also: http://mail-archives.apache.org/mod_mbox/hadoop-zookeeper-user/200905.mbox/%3c4A2009B1.3030603@yahoo-inc.com%3e

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