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Hooks
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Hooks are points in the Grouper API that will callback custom code if configured to do so. The custom code has the opportunity to be notified that something happened, change data as it is being operated on, veto operations, kickoff other logic (log something, call another grouper API method, etc).
Hooks are available for the following database persistable objects: Group, Stem, Member, Membership, Composite, Field, GrouperSession, GroupType, GroupTypeTuple
Getting started with hooks
Proof of concept (A veto hook)
Hooks Example - Assign a Unix id to each new group
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Each of these objects has low-level hooks associated with it: preInsert, postInsert, postCommitInsert, preUpdate, postUpdate, postCommitUpdate, preDelete, postDelete, postCommitDelete.
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To configure a hook, subclass one of the hooks base classes, e.g. GroupHooks, MembershipHooks, etc. Then either register this in the grouper.properties (see grouper.example.properties[broken] for documentation). Note the class must be threadsafe, as an instance is cached and called repeatedly (i.e. dont store instance vars etc)
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To find out how the data has changed (in an update or delete), you can use the dbVersion API. Note, this is probably only available in the "pre" hooks.
To veto a hook, throw a HookVeto which is a runtime exception. The specific hooks which is vetoing will be assigned to the exception, and will be known wherever it is caught. This HookVeto takes a system name and a friendly description of a reason why it is being vetoed. The system name can be used to look up a localized error message. The friendly version can be used for logging or if a localized message doesnt exist. You can only veto pre and post synchronous hooks. You cannot veto asynchronous or postCommit hooks. You also cannot veto lifecycle hooks (e.g. hibernate init).
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2008/07/09 02:18:05.482 GrouperHooksUtils.executeHook(174) - START: Hook GroupTypeTupleHooksImpl.groupTypeTuplePreInsert id: PSPTRJ8J 2008/07/09 02:18:05.497 GrouperHooksUtils.executeHook(181) - END (normal): Hook GroupTypeTupleHooksImpl.groupTypeTuplePreInsert id: PSPTRJ8J (15ms) 2008/07/09 02:18:05.497 GrouperHooksUtils.executeHook(174) - START: Hook GroupTypeTupleHooksImpl.groupTypeTuplePostInsert id: PSPTRJ8K 2008/07/09 02:18:05.497 GrouperHooksUtils.executeHook(186) - END (veto): Hook GroupTypeTupleHooksImpl.groupTypeTuplePostInsert id: PSPTRJ8K (0ms), veto key: hook.veto.groupTypeTuple.insert.name.not.test4, veto message: name cannot be test4 |
Use cases
- Validate that a group extension conforms to standards, veto if not
- Only grouperLoader itself (or someone in the wheel group), can add a member to a group with type "grouperLoader"
- A new or updated group emailAddress attribute should not be in use by another group or subject
To do
- Add more high level hooks
- Collect and code use cases
See also
Access Management Features Overview