[Zope-dev] Xron fragility

[Steve Alexander]

The Xron product seems rather "fragile" in use.

That is, if things go wrong when an Xron DTML Method is triggered, that
method doesn't get rescheduled.

An example of this is that my intranet DNS server needed to be rebooted.
Xron couldn't look up the appropriate domain name, and stopped working.

------
2000-10-11T08:16:34 PROBLEM(100) Products.Xron.Loggerr 
Trigger event: http://my.development.server:4080/my_xron_method
Trigger time: 2000/10/11 09:14:00 GMT+1
Failed to trigger event.
Type=bci.NotAvailable
Val=host not found (File:
http://my.development.server/my_xron_method/trigger Line: [])
None None for None
------
2000-10-11T08:19:04 PROBLEM(100) Products.Xron.Loggerr Failed to disarm
event


Also, if something bad happens in the Dispatcher thread, the thread
dies.


Before I leap in and start patching Xron, I'd like to have a discussion
about how Xron should handle problems.

My first thought is that on errors in the dispatcher thread, Xron should
enter an "error state" where it probes every so often to see whether it
can resume normal operation. The length of time between probes could
increase with each probe, to give good performance with transient
problems whilst preventing Xron from choking resources. 

--
Steve Alexander
Software Enigneer
Cat-Box limited
http://www.cat-box.net