[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2770) Action observers for event listeners

[Jürgen Kellerer (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=42229#action_42229 ] 

Jürgen Kellerer commented on HHH-2770:
--------------------------------------

Even if this case is old, I'd like to add that there's one more, really important use case that could be addressed with action observers if they can be registered through a (hibernate specific) public API or through service loading.

Occasionally it's quite hard to trace why a particular action failed during a flush of many queued actions (especially with high concurrent load). This is the case as the exceptions that are thrown do not include "toString()" or similar of the entities that failed and as a result one needs to work out the problem with DB exceptions which are usually not really helpful either. Under normal circumstances it's also not efficient to keep all persisted and updated instances externally as this causes lots of overhead and design issues. While statement logging is an option for debug systems, it doesn't really help if the error appears in a system being in production.

Basically an action observer (if designed that way) could not only observe the execution of an action but also observe the exception that may be thrown. 
If designed that way an observer can registered that logs parts of the action queue or at least the entity that failed, making it a lot easier to trace why things went wrong.

> Action observers for event listeners
> ------------------------------------
>
>                 Key: HHH-2770
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2770
>             Project: Hibernate Core
>          Issue Type: New Feature
>          Components: core
>            Reporter: Christian Bauer
>            Priority: Minor
>
> Talked to Steve about a feature he calls "action observers", which would allow the following use case:
> - Write a FlushEventListener
> - Observer for what has been deleted, inserted, updated (action queues)
> This removes some of the pain that comes from missing communication between listeners. For example, you can easily move code you would traditionally write in an Interceptor into a FlushEventListener if you only need inserted/deleted/udpated records.

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