[GRAAP-WG] Time Constraints Profile

[Dominic Battre]

Hello Costas,

I thought about this for time. My point of view is the following:

I can use my calendar application and define appointments for "every day
from now until next Friday, 9am-5pm". After entering this appointment
and going to the calendar view, I see one appointment each day. So
"every day from now until next Friday, 9am-5pm" was just an intensional
description of what can be expressed by an extensional description as
well (see http://en.wikipedia.org/wiki/Intensional_definition).

So what are the advantages and disadvantages of an intensional description?

1) Positive: compact representation
2) Negative: difficult to model, negotiate and evaluate adherence
3) Positive: can be used to model infinite number of repetitions (every
day until the end of the world)

I think that 3) has no real usecase as contracts should contain a well
defined end.

Considering 1) and 2) I am still in favor of the extensional
description. "every day from now until next Friday, 9am-5pm" becomes
just "2009/12/10 9am-5pm, 2009/12/11 9am-5pm, ..., 2009/12/18 9am-5pm".
When the user enters an SLA its GUI can still present "every day from
now until next Friday, 9am-5pm" but just render it as an extensional
set. Each individual time frame could be modeled as one SDT+GT.

I think the extensional description has the same expressiveness (as
mentioned, I don't see 3) as a usecase for us) but is easier to handle
and creates a leaner specification.

Best regards,

Dominic

On 12/07/2009 05:17 PM, Constantinos (Costas) Kotsokalis wrote:
> Hi Dominic,
> 
> Recurring patterns for service usage is something that is needed in many
> cases, even if not allowed by current technology/service providers. In
> an example scenario where someone rents VMs to execute enterprise
> operations s/w on them, (s)he would certainly prefer to load-balance
> over a number of them available during working hours, and half or less
> that number outside working hours, to save money. I know this is not
> something that current cloud providers offer (to the extent I'm aware
> of, at least) but I believe it's a realistic need, and fits with fully
> dynamic scaling scenarios.
> 
> On the same time, I do agree that it increases complexity, especially if
> one is willing to include constructs such as "on the first Monday of
> every month" etc.
> 
> Just my E0.02.
> 
> Best regards,
> 
> Costas
> 
> 
> On 7 Dec 2009, at 14:39, Dominic Battre wrote:
> 
>> Hello Costas,
>>
>> it would certainly be a possible extension.
>>
>> The question is do we want it? If we end up translating ical to XML we
>> come to a specification that is extremely powerful but very difficult
>> to implement.
>>
>> Our idea was to use the simplest language that would be useful.
>> Therefore, I would like to ask you and the others: Do you need
>> something like "every day, 9am-5pm"?
>>
>> Best regards,
>>
>> Dominic
>>
>> Constantinos (Costas) Kotsokalis wrote:
>>> Hi Dominic,
>>> Would you see fit to augment this also with some construct for
>>> defining periodic durations? E.g. to be able to say "every day,
>>> 9am-5pm", or things like that.
>>> Best regards,
>>> Costas
>>> On 7 Dec 2009, at 13:43, Dominic Battre wrote:
>>>> Dear GRAAP members,
>>>>
>>>> we have seen in various discussions that there seems to be a frequent
>>>> desire for a standardized term language to express when a service shall
>>>> be delivered.
>>>>
>>>> Examples are:
>>>>
>>>> - Making a hardware reservation of a cluster for interactive use
>>>>
>>>> - Co-allocation of resources of various types (hardware, network,
>>>> licenses, ...)
>>>>
>>>> - Defining a deadline for the completion of a job
>>>>
>>>> We have had a discussion about this in Banff after which Oliver and I
>>>> have prepared a proposal for a Time Constraints Profile for
>>>> WS-Agreement. This proposal has been uploaded here:
>>>>
>>>> https://forge.gridforum.org/sf/go/doc15832?nav=1
>>>>
>>>> We would be eager to hear your comments.
>>>>
>>>> - Is the proposal clear?
>>>>
>>>> - Is the proposal complete?
>>>>
>>>> - Does the proposal satisfy your needs?
>>>>
>>>> Best regards,
>>>>
>>>> Dominic
>>>> -- 
>>>> graap-wg mailing list
>>>> graap-wg at ogf.org
>>>> http://www.ogf.org/mailman/listinfo/graap-wg
>>
> 
>