So, I have the same question here--multiple thick clients (desktop RCP
applications), each with a DataContext tied to the same backend, and
potential database access (direct or otherwise) from other toolsets
out of my control. Is there a recommended strategy for refreshing each
applications singleton DataContext to stay in synch, or manually a
supplying refresh command to the DataContext to periodically update
(and, if so, with what/how)?
Kind regards,
Lawrence
===================================
Lawrence Gerstley, Ph.D.
PSMI Consulting
lawg...@gmail.com
Cel: (415) 694-0844
On Apr 8, 2009, at 4:22 PM, Malcolm Edgar wrote:
Hi Joe,
Your singleton cache is going to need to be update periodically if
there are changes to the under lying database from other sources.
regards Malcolm Edgar
On Thu, Apr 9, 2009 at 7:45 AM, Joe Baldwin
<jfbald...@earthlink.net> wrote:
I *think* this is a life-cycle question, but there may be more to it.
Proposed Design:
1. Standard Web page JSP using Tomcat server.
2. One of the JSP's accesses a singleton.
3. The singleton accesses and stores a database field via Cayenne
(presumably when the class is initially loaded) and should never
need to
access the field again.
4. I would prefer it if the database field change would be
propagated to the
singleton upon the next new client-Session.
Problem
1. Here is the odd bit: the database field can be modified via
direct access
to the database (SQL, etc).
2. Cayenne appears not to see this change even when a new client-
Session is
initialized.
3. I can *force* the singleton to recognize the change by
restarting Tomcat
(but that is totally lame :) )
4. Unless I have made a mistake (which is possible), the singleton
should be
only associated with JSP session scope. But if I am wrong, this
could be
the problem.
Obviously, I have a misunderstanding about either Cayenne or Tomcat
caching
or perhaps its a combo of the two. It appears from my tests that the
singleton class may be constructed the first time after Tomcat is
restarted
and then remains persistent even across different sessions.
Are there any suggestions as to a simple design in which my
singleton forces
re-initialized (i.e. refresh the Cayenne object from the DBMS data)
upon
each new session?
Thanks,
Joe
