[EnMasse] Fwd: A coming change in the router's default behavior

[Ulf Lilleengen]

FYI this affects EnMasse as well, and clients must now send messages 
presettled for store_and_forward=false, multicast=true addresses.

Since we built from master, we already have this new behavior in the 
upstream 0.8.0 release, causing the broadcast systemtests to fail. I 
will fix those tests to send messages presettled.


-------- Forwarded Message --------
Subject: A coming change in the router's default behavior
Date: Thu, 13 Apr 2017 16:56:45 -0400
From: Ted Ross <tross at redhat.com>
Reply-To: users at qpid.apache.org
To: users at qpid.apache.org

Qpid Dispatch Router users:

Please be advised of a coming change to the default behavior of the 
router.  The details are outlined in

     https://issues.apache.org/jira/browse/DISPATCH-744

There are two characteristics of the router that conspire to provide a 
potentially misleading/erroneous situation.

First, when unsettled deliveries are sent to a multicast address, the 
router converts them to pre-settled deliveries and sends a 
settled/accepted disposition back to the producer.

Second, when congestion occurs on an outgoing link, pre-settled 
deliveries are aggressively dropped to alleviate the congestion.

This combination means that if congestion occurs while sending messages 
via multicast addresses, deliveries may be silently dropped even though 
the sender was provided an accepted disposition.  This is at best 
misleading.

The change that will be committed to the master branch (for future 
release 1.0.0) will cause all unsettled deliveries to multicast 
addresses to be rejected with an error stating that only presettled 
deliveries can be multicast.  This behavior will be the new default, but 
users will have a configuration option to select the original behavior 
if they so desire.

-Ted

---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe at qpid.apache.org
For additional commands, e-mail: users-help at qpid.apache.org