[ogsa-dmi-wg] StartNotBefore element in Data Transfer

[Michel Drescher]

Hi Mario,

yes, this is the only reliable way of modus operandi.

Having said that, I propose to add an additional chapter 3.4  
explaining the use and semantics of xs:dateTime in OGSA-DMI:

" 3.4 Using dates and times in OGSA-DMI

OGSA-DMI makes use of the XML Schema data type xs:dateTime in various  
places, for example to express the point in time when a DTI has  
finished, or to convey a certain point in time in the future where the  
DTI shall start transferring. However, the XML Schema data type  
xs:dateTime allows to give dates and times both with and without time  
zone. While dates and times including time zones express absolute  
dates and times on a timeline, dates and times without time zones  
express relative dates and times that must be interpreted according to  
some context. This context-dependant interpretation often leads to  
ambiguous situations.

Hence OGSA-DMI service implementations, when emitting dates and  
times,  MUST express all dates and times (for example, the DTI's  
StartTime attribute) using a time zone to relieve clients of knowledge  
of the service's location. Also, OGSA-DMI implementations, when  
receiving dates and times that do not include a time zone, MUST  
evaluate that date and time in the service's local time zone."

What do you think?

Cheers,
Michel

On 16 Oct 2008, at 12:23, Mario Antonioletti wrote:

>
> Hi,
>   I'm ok about the proposed change below - just one point of  
> clarification - only query that I have is the canonical time for  
> this is the server time in the timezone the server lives in - right?  
> I have a vague recollection that we did discuss this ...
>
>> For the group: I think we need to slightly reword the Functional
>> Specification better describing the StartNotBefore transfer  
>> requirement.
>>
>> It currently reads as:
>> "This represents the [startNotBefore] information element. The data
>> transfer encapsulated by the DTI MUST NOT start before the date, time
>> and time zone specified by this element. If not specified its default
>> value will be the date and time that the DTI was created. The DTI  
>> MUST
>> NOT enter the transferring state before this time unless the “Start”
>> operation on the DTI is invoked."
>>
>> I propose to replace that with the following paragraph:
>> "This represents the [start not before] information element. The data
>> transfer encapsulated by the DTI MUST NOT start before the date, time
>> and time zone specified by this element. If not specified then the  
>> DTI
>> MUST wait for a client to invoke the Start operation before it can
>> enter the Scheduled state."
>>
>
> +1
>
> Mario
>
> + 
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> |Mario Antonioletti:EPCC,JCMB,The King's Buildings,Edinburgh EH9  
> 3JZ.   |
> |Tel:0131 650 5141|mario at epcc.ed.ac.uk|http://www.epcc.ed.ac.uk/~mario/ 
>  |
> + 
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Michel Drescher
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