db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Michael Dobrovnik (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-4944) Embedded Derby does not start when derby.jar is dynamically uploaded / added to the classpath
Date Tue, 14 Dec 2010 15:59:01 GMT
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:
         Environment: various windows versions, jdk1.6.0 and 1.5.0
            Reporter: Michael Dobrovnik
            Priority: Minor


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, but ceased to work in;

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
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, 


This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message