[Dev] Notification Manager using Item Queries

[Ted Leung]

Just so that we're clear here, I'm not invested in doing notification 
exclusively via queries, so I don't mind if we decide to do a "regular" 
notification manager.  Having said that...

On Dec 6, 2004, at 11:12 AM, Brian Kirsch wrote:

> Technically I think it is possible to use item queries to deliver 
> notifications across views / threads. My concern is with repository 
> performance. The additional number of refreshes and commits required 
> to propagate notifications across views is gonna add a lot of CPU 
> cycles to the Repository Layer.

What it comes down to is this.  If we have to actually communicate 
changes in items across views, then we will have to commit/refresh in 
order for those changes to be visible. This is a direct consequence of 
our transaction model.  At that point, adding a notification on top of 
that isn't going to be that much overhead, compared to the overhead of 
the commit.  The only way that I can see around this would be to pass 
all the values needed by the notified repository view in the 
notification itself.

I am also concerned about performance, but I also don't think that this 
is an all or nothing proposal.  If we do a regular style notification 
manager, we can always (gradually) switch over to a query based system 
if that turns out to be efficient enough.

Ted