How to access read-only Derby databases over a network client connection? - derby

Question

I'm trying to open a read-only Derby database over a network client connection (using ij / derbyclient.jar).
I have created a read-only database:
jar cMf sample.jar sample
The Derby Network Server is started.
I have tried the following connection URLs:
connect 'jdbc:derby:jar://localhost:1527/sample.jar';
connect 'jdbc:derby:jar://localhost:1527/(sample.jar)sample';
connect 'jdbc:derby://localhost:1527/jar:(sample.jar)sample';
But none of the above URLs work.
The only URL that works is:
connect 'jdbc:derby:jar:(sample.jar)sample';
It appears that read-only Derby databases can only be opened in embedded mode. Is this true ?
Solved:
After checking the "derby.log", the problem was that the read-only database needs to be able to create a temporary file.
derby.log:
java.sql.SQLException: Failed to start database 'jar:(sample.jar)sample' with class loader sun.misc.Launcher$AppClassLoader#1d450337, see the next exception for details.
...
Caused by: java.sql.SQLException: Failed to start database 'jar:(sample.jar)sample' with class loader sun.misc.Launcher$AppClassLoader#1d450337, see the next exception for details.
...
Caused by: java.sql.SQLException: Java exception: 'Unable to create temporary file: java.lang.SecurityException'.
...
Caused by: java.lang.SecurityException: Unable to create temporary file
The solution is to define a temporary directory for the database. This can be done with the "derby.storage.tempDirectory" property:
System-wide in "derby.properties":
derby.storage.tempDirectory=c:/temp
Database-wide
CallableStatement cs =
conn.prepareCall("CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(?, ?)");
cs.setString(1, "derby.storage.tempDirectory");
cs.setString(2, "c:/temp");
cs.execute();
cs.close();
The network URL is:
connect 'jdbc:derby://localhost:1527/jar:(sample.jar)sample';