Xesam meta-meta-data spec needs attention.

[Sebastian Trüg]

On Monday 30 April 2007 23:40:37 Phreedom wrote:
> I'm writing this on behalf of Strigi project.
>
> It's important to finish Xesam specs as soon as possible since lots of code
> and work starts to depend on meta-meta- and meta- data spec and it gets
> more and more complicated to make changes.
>
> I believe Xesam metadata bainstorm wiki page has shown that proposals
> mostly split along .desktop vs RDF representation line, with the essense
> being very similar. So it's about time to finish meta-meta-data and start
> actively working on meta-data spec.
>
> Another concern is KDE feature freeze on 1th june which is also going to
> affect our ability to implement Xesam.
>
> At the end of the e-mail is our lastest proposal for meta-meta-data
> specification.
>
> Best wishes,
> Evgeny
>
> Format specification of .fieldproperties files(DRAFT)
> ===========================================================================
>===========
>
> [Field]
> Uri=$URI
> ParentUri=$PARENTURI
> Name=$NAME
> Name[$LANG]=$LOCALIZED_NAME
> Description=$DESCRIPTION
> Description[$LANG]=$LOCALIZED_DESCRIPTION
> TypeUri=$TYPE
> Values=$VALUES
> Values[$LANG]=$LOCALIZED_VALUES
> Range=$RANGE
> MinCardinality=$MIN_CARDINALITY
> MaxCardinality=$MAX_CARDINALITY
> Indexing=$INDEXING
> Relevance=$RELEVANCE
> Comment=$COMMENT
>
> $URI(required)
>   Unique resource identifier of the property. Internally properties are
> identified by this ID.
>   Alternative to this would be [$URI] instead of [Field].

I agree with Mikkel here that we should not have multiple groups with the same 
name.

> $PARENTURI
>   URI of parent property. Parent relation is similar to inheritance.
> Usually child property
>   introduces some specifics/limitations/implications compared to its
> parent.
> $NAME(required), $LOCALIZED NAME
>   Short user-friendly name. This is the name users will see when file
> metadata is displayed to them.
>
> $DESCRIPTION(required), $LOCALIZED_DESCRIPTION
>   User-friendly property description. This is the description of property
> suitable for tooltips.
>
> $TYPE(required)
>   Property data type.
>   Valid values: string, string_enum, string_enum_ext, integer, float,
> boolean, datetime, binary.
>   string_enum type is a property that can only take one of the list of
> valid values provided by $VALUES.
>   string_enum_ext type is a property that can take any string value,
> however $values list provides
>   suggested values of this property.

How about using xml schema types here. That way a later mapping to RDF will be 
easy and Nepomuk can stay compatible without an artificial mapping.
The only problem here are the enumerations. XML Schema does support creating 
enumerations but I think they are complex types. How about this: the type 
will stay a string or an int or whatever. But if the VALUES field is set it 
is to be treated as an enumeration. I don't think we need the extra types 
here.

> $VALUES(required if $TYPE=string_enum or string_enum_ext),
> $LOCALIZED_VALUES Property value constraints. Default =  no constraints.
>   if $TYPE=integer|datetime|float, $VALUES=value1|value2|value3
>   if $TYPE=string, $VALUES=validation regexp
>   if $TYPE=string_enum, $VALUES=value1|value2|value3
>   if $TYPE=string_enum_ext, $VALUES=value1|value2|value3|*(or)
>   This syntax lets us directly use $VALUES as a regexp for validating user
> input. Yet it's syntax
>   is developer- and translator- friendly.
>   Suggestions on regex subset are welcome. KDE and Strigi is going to use
> QValidator and QRegExp for this.
>
> $RANGE
>   Numeric property allowed value range. Default = no constraints.
>   $RANGE=[minValue,maxValue>
>   [ and ] = inclusive. < and > = exclusive.

Actually there is no need to have RANGE and VALUES. Just merge them into 
range:
RANGE=1,4,5,2.3
RANGE=1-7
RANGE=hello,bello,wello

> $MIN_CARDINALITY
>   Minimum cardinality. Minimum number of properties of this type you must
> set for a given file.
>   Lets specify mandatory properties. Default is 0.
>
> $MAX_CARDINALITY
>   Maximum cardinality. Maximum number of properties of this type you can
> set for a given file.
>   Default is infinity.
>
> $INDEXING
>   Values=fulltext, atomic, none, TBD. Default = TBD.

what is this supposed to do?

> $RELEVANCE
>   Defines how relevance of the file is affected if a match is found in this
> field. Default = 1.0
>
> $COMMENT
>   Developer comment. Users won't see this.
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