[DISPATCH-1360] forward pre-settled messages as unsettled within the dispatch network

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.8.0
• Component/s: Router Node
• Assignee: Unassigned
• Reporter: Ken Giusti
• Created: 10/Jun/19 18:06
• Updated: 09/Sep/19 21:22

Description

Possible approach to credit replenishment for pre-settled messages.

For unsettled messages the router correlates the eventual settlement of the message with credit flow to the sender.  This provides a reasonable method for rate limiting the sender.

However this approach does not apply to pre-settled messages.   For these the router simply grants sender credit when the message is forwarded, which tends to over-provisioning credit.

Let's try to apply the behavior of the unsettled case to the settled by forwarding presettled messages as unsettled between routers.   It would work something like this:

• presettled msg arrrives at ingress router - no flow granted
• ingress router adds a "presettled" flag to the annotations and forwards the message into the routing network as unsettled.
• at the egress router if the "presettled" flag is in the annotations the message is forwarded to the receiver as presettled.
• the egress router generates an PN_ACCEPTED/Settled event for the message
• which travels back to the ingress router which uses that event to grant flow to the sender.

de[devil]tails, etc...

Issue Links

• is depended upon by: DISPATCH-1367 Move credit/flow management out of core and move it to the I/O threads