in the hibernate reference document , I found something about version columen , but how to use it , and which module is the implementation of it.

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4.1.7. version (optional)
The <version> element is optional and indicates that the table contains versioned data. This is particularly useful
if you plan to use long transactions (see below).


column (optional - defaults to the property name): The name of the column holding the version number.
name: The name of a property of the persistent class.
type (optional - defaults to integer): The type of the version number.

Version numbers may be of type long, integer, short, timestamp or calendar.

You need to add a field (with setter and getter) for the version in you persistent object, and use the version element in the mapping. The version gets incremented everytime the object is updated.

If 2 concurrent users update the same persistent object (e.g version=5), the first user increments the version (version=6), and the second gets a StaleObjectStateException when trying to commit the change (his object has version=5 while the corresponding object in the database has a version of 6). This exception can be used to suggest the reloading of the persistent object.

mota