Hi Sanne,
Multi-release JARs sound promising. I'll forward your suggestion to the HANA JDBC
driver team.
Thanks,
Jonathan
-----Original Message-----
From: sanne.grinovero(a)gmail.com [mailto:sanne.grinovero@gmail.com] On Behalf Of Sanne
Grinovero
Sent: Monday, March 12, 2018 4:45 PM
To: Bregler, Jonathan <jonathan.bregler(a)sap.com>
Cc: hibernate-dev(a)lists.jboss.org
Subject: Re: [hibernate-dev] Hibernate support for JDBC drivers targeting multiple JVM
versions
Hi Jonathan,
personally this looks like an issue with the driver as class
initialization could be triggered by a number of things, it's going to
be hard to dodge them all, not least all containers and servers have
their own peculiarities in how they load and wrap drivers and
datasources; could you suggest the HANA JDBC team to release
multi-release jars? That would be safer, and also avoid issues with
other tools beyond Hibernate ORM.
-
http://openjdk.java.net/jeps/238
Thanks,
Sanne
On 12 March 2018 at 15:27, Bregler, Jonathan <jonathan.bregler(a)sap.com> wrote:
Hi,
in a recent version of the HANA JDBC driver the new JDBC 4.3 features that came with Java
9 have been implemented. The driver itself is still compiled for Java 7 (javac -target
1.7). So the driver should also be usable with a JVM 7 or 8. This works as expected until
Java reflection is used to determine, for example, the existence of a method on the
connection class. Hibernate uses this approach in
org.hibernate.engine.jdbc.env.internal.DefaultSchemaNameResolver#determineAppropriateResolverDelegate
to determine if the connection class implements the #getSchema method. In this case the
JVM tries to load the entire connection class including the non-existing new interface
java.sql.ShardingKey. The result is a java.lang.NoClassDefFoundError being thrown which
isn't caught anywhere causing the Hibernate bootstrapping process to fail. I've
attached a sample stack trace to this mail.
Situations like this can also occur in other places, for example, when getting a
connection from a Hikari connection pool.
My question is now how you think Hibernate should handle situations like this. Do you see
it as a JDBC driver issue? Should Hibernate ignore the error and continue with a
conservative guess if possible (e.g. assume that the connection class doesn't
implement #getSchema)?
Thanks,
Jonathan
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