[Xesam] Sorting API to be more flexible

[Arun Raghavan]

On Tue, Jun 24, 2008 at 6:35 PM, Mikkel Kamstrup Erlandsen
<mikkel.kamstrup at gmail.com> wrote:
> 2008/6/24 Mikkel Kamstrup Erlandsen <mikkel.kamstrup at gmail.com>:
>> 2008/6/13 Mikkel Kamstrup Erlandsen <mikkel.kamstrup at gmail.com>:
>>> 2008/6/13 Jos van den Oever <jvdoever at gmail.com>:
>>>>
>>>> 2008/6/13 Urho Konttori <urho.konttori at nokia.com>:
>>>> > We have been evaluating the Xesam for multiple uses at Nokia and one of
>>>> > them is media player use. In many cases, where all the songs need to be
>>>> > listed, they need to be listed with three sorting criteria: Artist,
>>>> > Album, Track#. Xesam provides only two sorting criteria. Now, you might
>>>> > argue that the application should do the tertiary sorting, but then if
>>>> > we say that, then why two sorting criteria, or one?
>>>> >
>>>> > I'm quite sure this is not the only use case where tertiary sorting (or
>>>> > even more) would be beneficial.
>>>> >
>>>> > Also, the API looks a bit glued when you have primary and secondary
>>>> > sorting as the session properties. Why not instead change it to an array
>>>> > of sort criteria? So, as to call it just sort.fields?
>>>> >
>>>> > It would be very good if this sort of change could still be done to the
>>>> > xesam 1.0 spec, either next to the current primary and secondary
>>>> > sorting, or better yet, as the only way to set the sort order. It would
>>>> > be much cleaner way to do it.
>>>> >
>>>> > Anyway, I'm looking forward to comments on the subject.
>>>>
>>>> I agree with your suggestion.
>>>> We would also need a way for the server to specify what type of
>>>> sorting it supports.
>>>> For example a readonly property: sortableFields and a property that
>>>> says how many sorting fields can be used.
>>>> Some servers may not support sorting at all (grep) or allow only
>>>> sorting on one field.
>>>>
>>>
>>> I am also for this, although I think it is quite a big feature compared to
>>> our current freeze level.
>>>
>>> It is a good point you raise Jos. I do however think that it might be
>>> acceptable to require the servers to be able to sort the hit data. Otherwise
>>> one might have to pull massive amounts of hits over the wire only to get
>>> those with the highest atime at the top.
>>
>> Consider this thread bumped. It is our list of blockers I recently
>> posted about. We need a clear decision.
>>
>> I already made my point above.
>
> There has been some discussion on this on IRC which have led me to
> believe that the following solution would be optimal for all:
>
>  * Scrap sort.primary and sort.secondary.
>
>  * Introduce three new session properties:
>
>  - sort.fields a read/write list of fields to sort after, in that
> order. Default value ['xesam:relevancyRating']. The server should
> truncate this list to to the size specified in vendor.maxSortFields if
> too many sort fields are requested
>
>  - vendor.sort.maxfields a readonly uint. Specifies how many fields
> in sort.fields will be taken into account, as mentioned, sort.fields
> should be truncated at this length. This property must be 1 at
> minimum. If this value is 0 any number of fields can be used. Default
> value is undefined.
>
>  - vendor.sort.fields a readonly list of strings naming all fields the
> server can sort after. If this list is empty all known fields can be
> used for sorting. Default value is [].

I think the proposal sounds reasonable. Beagle won't be able to
support more than xesam:relevancyRating for now, AFAIK, but that's
fine.

Cheers,
-- 
Arun Raghavan
(http://nemesis.accosted.net)
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