[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-2501) Read-only state of an entity in a session to propagate into subsequently lazy-loaded entities.

[Christian Bauer (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2501?page=all ]

Christian Bauer updated HHH-2501:
---------------------------------

    Priority: Minor  (was: Major)
        type: New Feature  (was: Improvement)

This was actually a question I got last week in training and we concluded that a cascade="readonly" (or similar) might be quite useful. The request was to allow read-onl entity instances in persistent state within the identity scope, avoiding data aliasing problems with StatelessSession, but still being able to initialize proxies and collections without the memory overhead of snapshots. I guess most people are hit by this when they try to use the same mapping metadata for OLTP and reporting.



> Read-only state of an entity in a session to propagate into subsequently lazy-loaded entities.
> ----------------------------------------------------------------------------------------------
>
>          Key: HHH-2501
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2501
>      Project: Hibernate3
>         Type: New Feature

>   Components: core
>  Environment: any
>     Reporter: Gunther Schadow
>     Priority: Minor

>
>
> ISSUE:
> Given an Entity entity and after Session.setReadOnly(entity), if the entity has lazy collections, lazy properties etc., other Entities are loaded into the Session upon navigating the object graph in the default read-writable state. However, it seems more reasonable to maintain the read-only state of the owning object.
> REQUEST:
> Ability to propagate read-only state of an entity in a session into other lazy-loaded entities.
> BACKGROUND:
> We have a system which permits users to make concurrent transactions which involve many of the same objects. Usually no changes happen on these shared objects, but instead connections (links) are made between these objects and new objects. For example, say you have an online meeting system, and every Meeting held has a link to a number of User object. The User objects are never changed in a Meeting, but there is a Relation called Participation (of User in Meeting) to which new relationships are added. When a new meeting is saved, it wants to save the  User objects simply because a new Participation link entry was added to the collection.
> To an extent we can prevent this from happening by setting the Users explicitly to read-only. However, now suppose we added a function "Invite your Friends" to a Meeting, in which we would simply go:
> for(User friend : currentUser.getFriends())
>    meeting.addInvitation(friend);
> Now an Invitation is like a Participation, and would be added into the User but now it wants to save these users just for a version upgrade only because they have received an Invitation.

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