[Seaside] Question about access to a shared object

Ron Teitelbaum Ron at USMedRec.com
Wed Oct 10 12:51:57 UTC 2007

Hi Jason,

Be sure to look at SharedQueue.  You can have seaside put an update request
into the queue and then have a separate process pull from that queue and
update your objects.  This will open a bit of a window for stale data, but
if your application has a low threshold requiring data accuracy this is a
good way to go.

This actually gets easier if you add a DB.  You can have a process pulling
from a queue table, to update your object, and then you can easily support
multiple running images.  But once again you have a stale data issue.

If you must have an accurate answer then you need to lock the shared objects
for read and write. (or handle exceptions on write if value changes)

Happy Coding,

Ron Teitelbaum
President / Principal Software Engineer
US Medical Record Specialists

> From: Philippe Marschall
> 2007/10/10, Jason Johnson <jbjohns at libsource.com>:
> > Hello all,
> >
> > I am making several web sites, which all have their own way to present
> > underlying objects.  So something like (in a concise format, something
> > like python):
> >
> > Class RealUnit:
> >   quantity
> > Class MySite:
> >   myItems
> > Class SiteUnit:
> >   realUnit
> >
> > So sites all have a collection of site units, and site units are
> > one-to-one with real units, they simply present a different perspective
> > of that same unit.  SiteUnit is just a presentation, it has no quantity,
> > only real units do.  So my question is, if two sites try to decrease the
> > quantity of the underlying real unit does that have to be protected by a
> > mutex or something?
> Sure. Have a look at the latest patches from Andres. These put
> semaphores in a "semms to work" state.
> > I would expect so, but perhaps Seaside already protects access to all
> > object access somehow?
> How would Seaside know about your objects? Seaside only knows about
> its own objects.
> Cheers
> Philippe
> > Thanks,
> > Jason

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