How can I expose a C ODBC connection to a JVM using JNI?

Question

I'm embedding a JRE in an existing C application using the invocation API, and I'd like to be able to use JDBC to work with the database in that code. This application is a transaction processing application, and the database transaction is managed by code in the C portion of the application, and the java code must run within that transaction. This means that I can't open a new connection, I must re-use the existing one.

So, is there a way to provide JDBC access to an existing ODBC connection handle when setting up the JRE? Some JDBC-ODBC bridge, perhaps, but unlike the existing driver by that name, one that can be set up to use an existing connection and transaction.

My other options, as I see them, are as follows:

• Provide java equivalents for every C operation that is possible in the application (this is not desirable for a great many reasons -- we have a great many methods and duplicating them is a pain in the ass.

• Write my own JDBC driver that wraps the ODBC connection with JNI. Sure, it'd be a fun weekend (month) project, but I expect to need something done faster than that.

Help me, Stack-Overflow, you're my only hope!

Answer 1

Sun provides a JDBC-ODBC bridge in the JDK.

EDIT: Rereading sounds like you already know about it and don't want to use it.

Answer 2

Don't know whether this'll work, but... I had a quick look at the decompiled source code of Sun's JDBC-ODBC bridge. Seems like you could subclass the JdbcOdbcConnection so that it initializes itself with a known connection handle and an already-opened state. This assumes that the connection handles on the Java side are actual ODBC connection handles or pointers to connection objects, and that ODBC libraries used by the JDBC-ODBC bridge and your code are compatible in the sense that they can share connection handles.

You need to check whether Sun's license allows developers to perform such trickery though.