Re: Optimistic Locking Example
Re: Optimistic Locking Example
- Subject: Re: Optimistic Locking Example
- From: Ken Anderson <email@hidden>
- Date: Mon, 23 May 2005 08:13:59 -0400
Dimitri,
Kieran gives a lot of good reading examples, but I'll tell you what I
think is happening:
When the first user commits their changes, the snapshot (what EOF
uses to know what was fetched from the database regardless of your
changes) is updated to reflect the newly saved changes.
At this point, the EO that is in the second user's session gets its
values updated, because it isn't dirty yet (this is done through a
notification system that keeps objects in sync if they're changed).
It isn't dirty yet because, since you're using the web, it has no
idea that you changed the fields on the web browser (since you
haven't posted that change yet).
So, after the first user commits, all the copies of the object are
updated to the first user's changes. Now, when you hit 'save' for
the second user, it happily modifies the current version of the
object, and successfully saves.
Ken
On May 23, 2005, at 7:44 AM, Dmitri wrote:
Hi every1,
i wanted to ask if some could send me small example programm for
optimistic locking. I mean i tryed to write one now. Just made
simple WOApplciation "Test".
Than added to this e Emodel like "test".
Now i had Applicatin Test.woa qwith nice model in it
"test.eomodeld" with only one Table "Test", with 3 attributes.
testid (PrimaryKey Locked), testfield1(Integer, Locked), testfield2
(String Locked).
Now if i try to get on this applicatipn from 2 differend Browsers
and editing same object there. Like User1 takes this object to
edit, Than user2 takers this object to edit. User2 saves Changes.
User1 saves changes. here must be actually exeption from Optimist
locking, that object was already saved and have changed his values,
but nothing happens. values just overwrite last saved data in
databse. Do i understand it right, that my Optimistic Lockign thing
is not working ?
So if some1 could write small application with using and actually
getting exception on saving from two different instances, i would
very appreciate this.
Dmitri
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