In versioning repositories, the version storage appears as a protected subtree of each workspace. By placing listeners on this subtree a client can be alerted to versioning events. The events generated will reflect the changes made to the version storage area (for example, the addition of a new nt:version node below an nt:versionHistory node) as a result of the check-in operation. From this information the source of the check-in can be determined (for example, the nt:frozenNode's jcr:frozenUuid property holds the UUID of the workspace node that was checked-in).