I am using distributed transactions in a BDB JE application to coordinate transactions across multiple BDB JE environments. I want to set the transaction isolation level to serializable. To begin distributed transactions, I use an Xid that I generate and have to ensure is globally unique, eschewing BDB JE's native Transaction class. The transaction branch that starts is ThreadLocal, so null is passed into the transaction field in operations. So how do I set the isolation level? Is the isolation level already defaulted to serializable? My Google-fu isn't turning anything up...
I am a huge fan of Stackoverflow, but I'm also the Product Manager for Oracle Berkeley DB so I have to first suggest that the "right place" to ask this kind of question is on the OTN Forum for BDB JE (http://forums.oracle.com/forums/forum.jspa?forumID=273).
Here are the Javadoc for BDB JE http://download.oracle.com/berkeley-db/docs/je/3.2.76/TransactionGettingStarted/BerkeleyDB-JE-Txn.pdf
And here is information about LockMode http://download.oracle.com/berkeley-db/docs/je/3.3.62/java/com/sleepycat/je/LockMode.html
Try Google-Fu of: site:download.oracle.com berkeley db java edition
The docs for all products live in the Oracle "DocArch" system which publishes to the download server (because when it was first designed there was no "Interweb" only CDROMs and printed materials which you would download, get it?).
Good luck.