On 14.05.2007, at 21:58, Gregg Wonderly wrote:
As a general rule of listener use, anytime you add a listener for some
kind of notify, you need to query with the same template that the
listener has to make sure that there was no item added between the
last
notify/query and the next notify registration. Odd things can really
happen in distributed systems.
.. using a background timer based operation to rerun the query
periodically.
Hi. I am still experiencing these dropped notify() calls. But with
your two suggestions implemented, I am making sure, that no objects
are getting lost. Only disadvantage: In case of a dropped notify()
call, I will receive the related objects with a bit of delay. (My
background timers checks once every second.)
In my specific case, there are _at least_ 200 ms between each space
write() operation. And, as mentioned earlier, my master, slave and
JavaSpace VM's are (currently) running on the same physical machine.
This is why it is a bit hard for me to understand, how notify() can
be so unreliable. I'd say, I am having one dropped notify() call for
every 50 objects written to space. Roughly.
I still need to implement your third suggestion (below). I can do so
next week. And I will report back, if this fully fixes the issue for me.
With Javaspaces, you should typically request notification, and
then do a read
to see if there is an entry that matches the same template, and
then take that
entry to process it if so.
Thank you.
Timur
