On Tuesday 05 June 2007 12:58:51 Mikkel Kamstrup Erlandsen wrote: > > > Unless that document is horribly outdated I can't se how. A DataSource > > > designates the origin of some DataObject if I'm not mistaken. This was > > > > also > > > > > the idea behind xesam sources. > > > > > > They might differ on the technical level but the idea behind them seems > > > > the > > > > > same, or is there something i miss? > > > > AFAIK DataSource was intended to store properties of specific data > > storage/extraction plug-ins. Usually many files will point to a single > > DataSource object. > > > > In xesam Sources approach lets us assign and expect source-specific > > properties > > to files like compressedSize and compressionAlgo for archive contents or > > attachment encoding type(base64 etc) for email attachments. > > > > That is by knowing the source type, we know what fields to expect, > > besides the > > fact that explicit source type knowledge is useful as-is for presentation > > to > > the user. > > > > The more sources and the more exotic sources we have, the more benefits > > we get > > from structuring the source hierarchy and source-specific fields. Not > > going > > to repeat the long list of benefits of structuring the ontology I posted > > when > > we discussed explicit category-field bindings. > > > > We get these benefits with absolutely no extra overhead implementation-, > > storage-, performance-wise. > > > > For example, local copy and content creation dates belong to Source and > > Content respectively, while in NIE both belong to DataObject. > > Ah, ok, I see how they differ in concepts, but they are still quite > related. In Nepo a DataSource contains the information about the source in > xesam it would contain what the source of an actual object is.
In nepomuk DataSource contains the information about the plug-in/backend, which may correspond to several xesam sources. In xesam, we explicitly specify what source type we have and assign properties provided by the source for the specific file. > I was not trying to imply that a Source shouldn't be able to imply which > fields are available on a given object. Just that I would like a field > Category and a field Source that both imply a set of fields. I think we > might agree to a great extend :-) I just thought it was about time to document xesam sources and implications and in the meanwhile answer your question :) --Evgeny _______________________________________________ xdg mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/xdg
