Can I use JSO in a J2EE container?
We believe so. But we have not tested yet. Most important, JSO is not yet integrated to J2EE environments, so you will not be able to use features provided by them, like data sources or transaction management.

How does garbage collection work? Does it prevent me from accessing stored objects?
The garbage collector divides the database in partitions and makes an incremental collection. When collecting a partition, the garbage collector locks the partition exclusively. While the partition is being traced, objects from this partition become inaccessible. Objects from any other partitions are not affected. After tracing all partitions the collector sleeps for a while (can be configured) and then starts over again. The collector can also be turned off. However, turning off the collector does not avoid the creation and management of partitions.

Which privileges should I grant the database user JSO will use?
JSO must perform many database operations, like reading and writing data and creating and droping tables, indices and constraints. If it doesn't hurt make JSO use the database owner.

What should I do to test JSO with an "unsupported" database?
You should map JDBC types to database data types and create a property file, like those supplied in net.sf.jso.database package. Soon enough we will provide more documentation about this and also some JUnit test cases.

What happens if I need to modify a class that has objects stored?
Depends on the modification. If your modification concerns only to methods (adding, removing or modifying) there should be no problem, unless you modify jsoClassMetadata() method. Any other modifications may provoke mismatch with stored classes. A schema evolution tool/API should be used along such modifications, however none is available for the moment. Providing such features shall be a priority for the project.

What is a container class?
Is a collection (Collection, List or Set) or a map (Map). Arrays are not supported by JSO, but could also be considered as such.

My object model has a one-to-many relationship with a very large number of objects. Does JSO handle this well?
Suppose you were working exclusively in main memory, how many objects would you keep in a container object? Even using lazy loading techniques, retrieving too many objects from the database to memory may not be handled efficiently. We have no data or criteria about that yet.

Does JSO support crash recovery?
Depends on the underlying database. Storage operations (including metadata management and garbage collection) are done under transactions. If the database supports JSO will support too.