Observers would be awesome especially with a couple enhancements / extensions:
An option for the observers to enter a special state if the WAN link goes down
to the "master" cluster. A read-only option would be great.
However, allowing certain types of writes to continue on a limited basis would
be highly valuable as well. An observer could "own" a special node and its
subnodes. Only these subnodes would be writable by the observer when there was
a session break to the master cluster, and the master cluster would take all
the changes when the link is reestablished. Essentially, it is a portion of
the hierarchy that is writable only by a specitfic observer, and read-only for
The purpose of this would be for when the WAN link goes down to the "master"
ZKs for certain types of use cases - status updates or other changes local to
the observer that are strictly read-only outside the Observer's 'realm'.
On 7/19/09 12:16 PM, "Henry Robinson" <he...@cloudera.com> wrote:
You can. See ZOOKEEPER-368 - at first glance it sounds like observers will
be a good fit for your requirements.
Do bear in mind that the patch on the jira is only for discussion purposes;
I would not consider it currently fit for production use. I hope to put up a
much better patch this week.
On Sat, Jul 18, 2009 at 7:38 PM, Ted Dunning <ted.dunn...@gmail.com> wrote:
> Can you submit updates via an observer?
> On Sat, Jul 18, 2009 at 6:38 AM, Flavio Junqueira <f...@yahoo-inc.com>
> > 2- Observers: you could have one computing center containing an ensemble
> > and observers around the edge just learning committed values.
> Ted Dunning, CTO