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From Rick>
Subject Re: scope for backing beans
Date Mon, 14 Feb 2005 16:38:46 GMT
Sean Schofield wrote the following on 2/14/2005 11:23 AM:

> With the application scope beans in JSF I have been toying with the
> idea of using them instead.  I was thinking that it might be possible
> to invalidate the bean (by setting the value to null) whenever a new
> item is added.  I haven't worked out the details yet but thread safety
> is an issue that jumps to mind.  Also, you'd have to have make sure
> that you were listening to every possible point where the list might
> change.

That last part is the tricky part. It's super easy if you know the data 
will only be altered by your web application. If that is the case you 
can forget even using application scoped items and simply use iBATIS for 
your persistence framework (uses regular SQL). It has some great caching 
mechanisms to handle the issues you are concerned with. For example 
whenever an update operation is performed (by calling your defined 
update procedure in an xml doc) you could set a flag in the udpate 
procedure that will clear the cache of other queries. The bottom line, 
though, is this is all nice, but everywhere I have worked the data often 
changes from some other point other than your web app. This is where it 
gets very ugly. What are you going to do when some other external 
procedure updates your backend data? Accounting for those entry points 
can be a  royal pain.


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