[Dev] Re: Recurrence discussion

[Lisa Dusseault]

Date range queries are quite different from all other queries, when 
querying calendar items -- this is something we've found in CalDAV, 
where we couldn't use the generic SEARCH mechanism to allow clients to 
see a week's worth of events.  Instead we invented a calendar time 
range REPORT which is the only kind of query to the server which 
attempts to expand recurrences.

To map that idea locally we might have two different query methods or 
query implementations.  If the query included a limited time range 
there could also be an "expand recurrences" flag (or not!).  If the 
query does not limit time range at two ends, the results will not 
expand recurrences.

Lisa

On May 13, 2005, at 10:36 AM, Ted Leung wrote:

>
> On May 11, 2005, at 12:12 PM, Jeffrey Harris wrote:
>
>> It seems to me that the options for having the calendar view see
>> occurrences of indefinitely recurring events for 20 year in advance 
>> are:
>>
>> 1) Make the view responsible for creating the relevant occurrences 
>> (yes,
>> I know, thunderous -1's from the list)
>> 2) Make the query system responsible for generating the relevant 
>> occurrences
>> 3) Generate enough events that we're sure the apocalypse will have
>> arrived before we run out (I support avoiding theology in Chandler :)
>> 4) Don't generate occurrences past a certain point, warn the user
>> visually if they're past that point
>> 5) Get the model/view contract refined to the point that we can use
>> proxy objects and avoid generating occurrences
>>
>> Does this seem like a complete list?
>>
>> I've been convinced that 5) is overreaching for 0.6.  1) is inelegant
>> and liable to incite insurrection.
>>
>> 2) seems fine to me, I don't know if it would be OK with Ted.
>
> If you do something like 4), with or without an end date, then all it 
> takes for
> queries to do this "automatically" is for the query processor to call 
> the
> method that generates occurrences, at least if you are asking for 
> occurrences
> that match a date range.
>
> However, if you are doing a query that looks for all occurrences 
> related to "Foo",
> then you might end up with a situation where the query result should 
> contain
> occurrences that have not been generated yet.
>
> So, for date range queries, I think it's possible for queries to 
> generate occurrences
> on the fly.  For other attribute based queries, I'm not so sure.  Note 
> that the problem
> I mentioned above exists even if queries don't try to do the 
> generation -- they are just
> calling the "make enough occurrences" method.
>
> ----
> Ted Leung                 Open Source Applications Foundation (OSAF)
> PGP Fingerprint: 1003 7870 251F FA71 A59A  CEE3 BEBA 2B87 F5FC 4B42
>
>
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