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https://issues.apache.org/jira/browse/DERBY-4944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12971589#action_12971589
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Michael Dobrovnik commented on DERBY-4944:
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In the meantime, a co-worker of mine also did some "independent investigations"
and came to additional insight:
we added the derby.jar to our classloader with
classLoader.addRepository(jarfile,null);
Changing this to
classLoader.addRepository(jarfile,new ProtectionDomain(new
CodeSource(jarfile.toURL(), new Certificate[0]), null));
also remedied the problem. so its not important that the patch barely did not
make it into 10.7
but since the apidoc of CodeSource implies that getLocation() can return null,
i think it is still a relevant patch.
thanks for your quick reaction.
> Embedded Derby does not start when derby.jar is dynamically uploaded / added
> to the classpath
> ---------------------------------------------------------------------------------------------
>
> Key: DERBY-4944
> URL: https://issues.apache.org/jira/browse/DERBY-4944
> Project: Derby
> Issue Type: Bug
> Components: Store
> Affects Versions: 10.6.2.1
> Environment: various windows versions, jdk1.6.0 and 1.5.0
> Reporter: Michael Dobrovnik
> Assignee: Dag H. Wanvik
> Priority: Minor
> Attachments: BDFF.diff
>
>
> Hi,
> For our workflow-system, we can use a variety of DBMS as the store engine.
> Derby is one of them especially popular
> for test and development purposes. During setup of our system, we allow to
> upload a jar file with the JDBC-Driver for the DBMS.
> In case of derby, we use the embedded mode and upload derby.jar. After that
> we add the jar to the repositories of our class loader
> and call
> Class drc = Class.forName("org.apache.derby.jdbc.EmbeddedDriver", true,
> ourclassloader);
> Driver drv = (Driver)drc.newInstance();
> this worked perfectly for many years up to version 10.6.1.0, but ceased to
> work in 10.6.2.1;
> i assume the unreleased future versions are affected, too
> when derby.jar is placed in the classpath manually before starting our setup,
> everything works fine regardless of the derby version.
> investigations lead to the following conclusion:
> - since rev. 982370 this is broken, in the immediate predecessor rev. 980035
> it worked.
> - rev. 982370 in the
> org.apache.derby.impl.store.raw.data.BaseDataFileFactory class introduced a
> new method
> private static String jarClassPath(final Class cls) which tries to find
> the jarfile from which derby was loaded.
> it contains the following lines:
> if ( cs == null )
> return null;
> URL result = cs.getLocation();
> return result.toString();
> but in the case, when we dynamically load derby,
> cs is not null but cs.getLocation() is null. so i propose to change the
> line with the if to:
> ...
> if ( cs == null || cs.getLocation()==null)
> return null;
> ...
> or maybe it would be better to surround the whole body of the method with a
> try catch, since it is not essential, and a null
> return value is also ok?
> thank you for your efforts concerning derby at large,
> Michael
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