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https://issues.apache.org/jira/browse/DERBY-4944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12971312#action_12971312
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Dag H. Wanvik commented on DERBY-4944:
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Thanks for tracking this down and the fix, Michael! It looks good to me.
I'll commit it after running our regression suite and back-port it to the 10.7
branch, so it would be included in an update release of 10.7 if there will be
one (likely). The initial release of 10.7 is going out the door as we speak, so
it will not make it there, unfortunately.
> 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
> 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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