[Freeipa-devel] Proposed changes to the HBAC grammar

[Stephen Gallagher]

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On 11/18/2010 06:16 PM, Dmitri Pal wrote:
> Adam Young wrote:
>> On 11/18/2010 05:27 PM, Dmitri Pal wrote:
>>> Adam Young wrote:
>>>   
>>>> On 11/18/2010 04:02 PM, Stephen Gallagher wrote:
>>>> On 11/18/2010 09:55 AM, Dmitri Pal wrote:
>>>>
>>>>     
>>>>>>> Steve can you summarize where we are and what we agreed to,
>>>>>>>            
>>>> please, and
>>>>     
>>>>>>> identify the questions that we need to answer.
>>>>>>>
>>>>>>>            
>>>> Simo, Adam and I had a long discussion on IRC regarding the time rules
>>>> today (complete log attached).
>>>>
>>>> The short version is that we're going to continue (mostly) with the
>>>> current grammar for the time rules, with a few changes.
>>>>
>>>> 1) We need to replace week-of-the-month with day-of-the-septet. This
>>>> day
>>>> should not be a range or multi-valued to eliminate confusion
>>>> 2) We need to replace the time range with a duration
>>>> 3) We should add startDate and endDate as attributes on the HBAC object
>>>> (separate from the accessTime). I propose these should be in LDAP
>>>> generalizedTime so that it's possible to construct filters around them.
>>>> This effectively sets the beginning and end of a periodic schedule.
>>>>
>>>>
>>>>     
>>>>> OK, just please stop calling it septet.  I think Drums, Bass, Piano,
>>>>>        
>>>> 2 Saxes,  Trumpet,  Trombone Jazz combo when I hear that.  It isl ike
>>>> octet versus byte....it means the same thing, and just annoys people.
>>>>
>>>>     
>>>>> What you really want is to call it week-of-the-month as opposed to
>>>>>        
>>>> week.  I realize that is more verbose, but we don't sound like
>>>> smarty-pants.
>>>>
>>>>
>>>>
>>>>
>>>> I've drawn up a new grammar definition and published it to the SSSD
>>>> wiki
>>>> (not currently linked from anywhere):
>>>> https://fedorahosted.org/sssd/wiki/HBAC_Grammar
>>>>
>>>> Please review and give feedback.
>>>>
>>>>
>>>>      
>>> I thought that first septet is the first seven days of the month based
>>> on earlier mails from Steven. Is this a true statement?
>>> The whole issue started with ambiguity of the notion of the "N-th week"
>>> of the month.
>>> What is it the week-of-the-month? Is it first seven day regardless what
>>> day of the week is the first day of the month (this is what I thought a
>>> septet is) or fist full week from Monday to Sunday or from Sunday to
>>> Saturday, or it is the first usually partial week? This is the ambiguity
>>> that we want to avoid!
>>>
>>> If the septet is what I think it is then we can't name it the
>>> week-of-the-month and IMO septet is a good term here. However then there
>>> is a bug in grammar as septet can be only 1-5 not 1-6.
>>>    
>>
>> OK, if this is really what is driving the grammar, I'm going to have
>> to NACK.
>>
>> Lets make something that is intelligible.  We don't want to be
>> inventing concepts like Septet.  Or Septave, since 8 days is already
>> called an octave.
>>
>> Here's the Cron line that Steve posted before.  It represents   THe
>> first wednesday of the month.
>>
>> 0 8 1-7 * 3
>>
>>
>> Lets keep the concept of week, starting on Sunday, add in the concept
>> of day of the month, and mix the two together.
>>
>> Does the current grammar (pre-septet) support that?  Something like:
>>
>> accessTime: periodic monthly between day 1-7  wednesday
>>

No, it does not. That's the specific reason for introducing septet, to
add this support. However, you make an interesting point. Perhaps we
could introduce a more generic term than septet to allow the above.

Though I think user comprehension would be made easier if we turned the
construct into something closer to:

accessTime: periodic monthly Wed between day 1-7


Though for the parser, I think it would be best to have a delimiter
between Monthly and Wed. I'm open to suggestions for what makes sense,
though. "encompass"? "inclusive"? "position"?

>>
> 
> It does not support this.
> It requires to specify either a week of the month after "monthly" and
> then day within a week (as numbers or the letter day names) or a set of
> numbers representing days or ranges of ways with thin the month.
> You can't with exiting schema unambiguously define "first Wednesday of
> the month" without the proposed "septet" changes.
> 


- -- 
Stephen Gallagher
RHCE 804006346421761

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