File Release Notes and Changelog
Release Name: 2.3
Notes: There have been no issues reported since Prevayler 2.3 was released as "beta" nearly a year ago, so we are promoting exactly the same release files to "production" status.
Changes: Changes from Prevayler 2.0 to Prevayler 2.3 ------------------------ SureTransactionWithQuery The Prevayler interface now supports an additional variation on execute(), for transactions that return a result but don't throw Exception. A new interface has been introduced, SureTransactionWithQuery, and a new execute() method has been added to Prevayler taking an instance of this interface. ---------------------- Journal file extension The default filename extension for transaction journals has been changed from '.transactionLog' to '.journal'. We always recommend taking a snapshot before upgrading either Prevayler or your own Prevayler-based code, so there shouldn't be any need to migrate old journal files. (The format of journal files has also changed, so migrating old journals would require more than just renaming the files anyway.) ------------------- Journal file format Transaction journals now have an internal structure of their own, rather than relying on ObjectOutputStream, in order to support configurable journal serializers. We always recommend taking a snapshot before upgrading either Prevayler or your own Prevayler-based code, so there shouldn't be any need to migrate old journal files. ------------------ Optimized rollback When using the StrictTransactionCensor, the deep-copy of the prevalent system to perform a rollback is now implemented in a pipelined manner so as to use significantly less memory. ------------------------ Configurable serializers A new Serializer interface has been introduced to support configuring serialization strategies for journals and snapshots. (The existing SnapshotManager abstract class, which had allowed limited customization of snapshot serialization, has been eliminated.) For snapshots, multiple Serializers may be configured, each with a different filename extension (though the extension must always end with "snapshot" or "Snapshot"). Only one will be used for writing snapshots, but others may be configured to support migration from earlier versions of your own code. For example, you might configure .v7snapshot with a Serializer including some schema migration code, while .v8snapshot is optimized for the current version of your business object model. The default is just .snapshot, using the JavaSerializer. For transaction journals, only a single Serializer may be configured, since we recommend always taking a snapshot before upgrading Prevayler or your own Prevayler-based code, so you will never need to migrate an old journal file. The filename extension may still be configured if desired, however (which must end with "journal" or "Journal"). The default is .journal, using the JavaSerializer. ------------------ Other enhancements Prevayler 2.3 includes some other behind-the-scenes improvements, including further increased transaction throughput and fewer threads created internally. Work on replication and an improved monitoring interface are still in progress.
