[occi-wg] Events ?

[Roger Menday]

On 19 May 2009, at 12:16, Gary Mazz wrote:

>
> You've got it...
>
> I do like the idea of long life messages and events. I think events  
> will
> be important just from the perspective of well know programming
> practices. I personally don't see unix signals going away for a long
> while.
>
> Resources can change states for one reason or another. Networking and
> storage (another network) are often victims of accidental switch
> reconfigurations resulting in loss of connectivity to endpoints.
>
> Configuration changes to resources outside the scope of the "active
> state" in the "life cycle model" may need to be logged or corrective
> action may be engaged.
>
> Long life remote service dependencies are another area where events  
> may
> be appropriate. Normally, I would suggest the applications handle
> occurrences between parties, but with migration as a normal
> circumstance, it may be out of control and scope of the parties.  
> Either
> the infrastructure will handle a "pause for migration" event or the
> container will tell the app which will tell the other party. Queuing  
> (a
> bridge) may be a way to avoid the issue as long as the service
> parameters are not violated. But it may be out of scope for
> interoperability.
>
> Security or privilege revocation is another area. Hard execution  
> breaks
> due to user or admin control is still another area.
>
> Polling may be inappropriate in many cases, driving up CPU loads and
> network bandwidth consumption.
>

Going down the ATOM route, one does get a feed of events (cf. recent  
discussions related to holding the lifecycle of a resource as a  
collection of states in a feed). In addition, there are a number of  
approaches out there to alert interested parties to an updated feed,  
stopping relentless polling somewhat. I wonder if that is enough ?

regards,
Roger

> I'll get them on the wiki in the later AM... I'm gmt -7
>
> -gary
>
> Sam Johnston wrote:
>> On Mon, May 18, 2009 at 7:55 PM, Gary Mazz <garymazzaferro at gmail.com
>> <mailto:garymazzaferro at gmail.com>> wrote:
>>
>>    Hi,
>>
>>     From the current discussions, there has been no mention of
>>    events. Will
>>    the occi support events ? What will the model look like ?
>>
>>
>> This is something I had thought about a little but not considered a
>> focus point for us. I did however consider the possibility of OCCI
>> messages being long lived in that they can be queued and passed over
>> transports like XMPP (this was one of a number of potential use cases
>> for signatures).
>>
>> The interest in doing this would be, for example, a client that has
>> rendered a number of resources and wants to know about state changes
>> and the like. They would just need to subscribe to the resource and
>> when the state changes they would be sent the updated entry.  
>> Similarly
>> an management system could ask for regular updates of e.g.  
>> performance
>> monitor counters.
>>
>> Does this sound adequate for your needs or do you have use case(s)
>> that require more - and if so, why aren't they in the wiki ;)
>>
>> Sam
>>
>
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Roger Menday (PhD)
<roger.menday at uk.fujitsu.com>

Senior Researcher, Fujitsu Laboratories of Europe Limited
Hayes Park Central, Hayes End Road, Hayes, Middlesex, UB4 8FE, U.K.
Tel: +44 (0) 208 606 4534


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