Oracle has released Berkeley DB Java Edition 3.2.13. This is an open source, non-relational embedded database written in Java. The data is exposed through "a Java Collections-style interface, as well as a programmatic interface similar to the Berkeley DB API." New features in this release include:
Berkeley DB Java Edition is published under a custom, viral license that is compatible with most major open source licenses. The license is a little confusing, though. It's not clear to me whether you have to release the source code to a Java program that calls Berkeley DB JE or just the source code to Java. The FAQ says, "The Berkeley DB open source license requires that software that uses Berkeley DB be freely redistributable. In the case of Perl or Python, that software is Perl or Python, and not your scripts. Any scripts you write are your property, including scripts that make use of Berkeley DB. None of the Perl, Python or Berkeley DB licenses place any restrictions on what you may do with them." That seems to indicate that it's just Java's source you have to release, which would be possible post-GPL and impossible pre-GPL, even for another open source project. Custom licenses are a pain. You can of course buy a payware license, but in classic Oracle fashion, they won't tell you what that costs until they figure out how much money you've got. The price probably also varies with how close we are to the end of Oracle's sales quarter too.