Yeah, this came up a few time (especially when people try to get rid of DPL).

One suggestion for implementation is that all this data should be sent to RAP store or any other store along with other properties so all the backends can really benefit from it.


On Sat, Jun 28, 2008 at 4:46 AM, Markus Krötzsch <> wrote:
On Samstag, 28. Juni 2008, Steren wrote:
> Hello,
> Creative Commons needs to be able to sort query results by last edit time
> for a specific use on the CC wiki.
> I wanted to know if anybody has already started working on implementing
> MediaWiki metadata in semantc queries.
> If not, I will be working on this next week.

We are planning this but do not have an implementation yet. The idea is the
have "edit time" to appear like a normal property that is set for all pages.
This could be done in various ways, e.g. by adding a hook that just writes
this edit time to the annotation store (like if the user would have entered
it). One could then essentially use the normal SMW store and query features.
The alternative to that would be to process "edit time" in a special way
during querying and to use the MediaWiki table directly -- I do not think
that this is the way to go (we just stopped using MW tables for categories
and redirects, simply because they were not designed for the kinds of queries
that we do, and since things like external RDF-stores cannot use data that
lives in MW tables only). So I would suggest to duplicate "edit time" in SMW
the store using a suitable property.

But such a property must also first be defined with a suitable datatype. The
SMW architecture there is not very extensible: we have normal properties that
need to have a defining Property page, and we have special properties that
are handled in a rather hard-coded way. There is a hack to add more special
properties, but these cannot be queried.

We therefore plan to revise the property architecture, make a class "Property"
that replaces the user-defined properties (currently represented by Title
objects) and the special properties (currently defined by constant numbers).
This change has not started yet, and there are some open issues to consider
first, but the result would hopefully be an architecture where an extension
can easily pre-define new properties that can be used for such special data
like edit times. Once this is in place, it will be even easier to add edit
time, last author, access level, etc. to the semantic store so it can be
queried efficiently.



> Let me know.
> Steren

Markus Krötzsch
Semantic MediaWiki

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