[Openstack] Notification Usage in OpenStack ... a report card

Sandy Walsh sandy.walsh at rackspace.com
Wed Sep 18 12:44:15 UTC 2013

On 09/18/2013 04:49 AM, Fei Long Wang wrote:
> Hi Sandy,
> It's an awesome post. Just some minor questions.


> 1. Are you aware of any project is using Oslo.Messaging? Actually, just
> like you know, the porting of Glance Oslo notifier is pending. And the
> main reason is Oslo.Messaging is coming.

Daniel answered this, but yes, the intention is to move to oslo.messaging.

Notifications are different than the olso rpc mechanism in a couple of ways:

1. they support requeue semantics. We can push notifications back on the
queue if the consumer can't deal with it.

2. they don't require a method with parameters on the consuming end. The
consumer can just pull the notification off the queue and work on it.
It's just a blob of data.

3. Later, we'll likely want to support dead-letter queues for
notifications that could not be processed. We don't want to lose these

So long as this is supported in Messaging, we're fine.

> 2. You mentioned that Glance implement the audit partially, could you
> please explain more from your point of view? Thanks.  

The "Importance of Usage Notifications" section sort of addresses this.
For billing purposes there should ideally be two notifications emitted.
The first would be the individual notifications for each billable action
(these could be incremental updates) and the second would be a summary
notification to indicate what the image or tenant cost for the day.  The
consumer could then verify that the incremental notifications and the
end-of-day summary matches.

Glance only supports the incremental notifications currently, iirc.

I think the image transfers are the only real billable event in Glance
right now. Not sure if image storage (snapshots for backup) would be

Hope it helps!

> Thanks & Best regards,
> Fei Long Wang (王飞龙)
> ---------------------------------------------------------------------
> Tech Lead of Nitrogen (SME team)
> Cloud Solutions and OpenStack Development
> Tel: 8610-82450513 | T/L: 905-0513
> Email: flwang at cn.ibm.com
> China Systems & Technology Laboratory in Beijing
> ---------------------------------------------------------------------
> Inactive hide details for Sandy Walsh ---09/17/2013 02:27:00 AM---Hey
> y'all! I took a little time to review most of the OpenStaSandy Walsh
> ---09/17/2013 02:27:00 AM---Hey y'all! I took a little time to review
> most of the OpenStack projects and check on their notifica
> From: Sandy Walsh <sandy.walsh at RACKSPACE.COM>
> To: "openstack at lists.openstack.org" <openstack at lists.openstack.org>,
> Date: 09/17/2013 02:27 AM
> Subject: [Openstack] Notification Usage in OpenStack ... a report card
> ------------------------------------------------------------------------
> Hey y'all!
> I took a little time to review most of the OpenStack projects and check
> on their notification support. Happy to say, adoption is good. There are
> things we could do better, but overall very positive.
> The article also talks a little about what makes for good notification
> support. Something for you all to think about at the Icehouse summit :)
> I'm sure I've made some mistakes along the way, so please let me know
> and I'll fix accordingly.
> http://www.sandywalsh.com/2013/09/notification-usage-in-openstack-report.html
> Look forward to your feedback!
> -Sandy
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