Traditionally, for instance, using JDBC, we can explicitly obtain a read lock when required, and then update the record, or when using EJBs, I believe there is a single instance of an Entity bean, say, for a given key, and the container single threads transactions on that bean instance unless READ-ONLY beans where it may be relaxed.
Wasn't sure how JDO deals with objects accessed from multiple threads (or sessions). Its not the gotcha's, but the behavior I guess I was looking for.
Rama
[ June 18, 2003: Message edited by: Rama Raghavan ]