[sc34wg3] The schema topic

[Robert Barta]

On Tue, Oct 28, 2008 at 12:17:32PM +0100, Lars Marius Garshol wrote:
> > The schema topic which represents an entire TMCL schema has
> > disappeared in this version. This topic is important for being able to
> > attach metadata to schemas, such as name, creator, version number,
> > source URL, etc etc. It is also important in order to provide an easy
> > mechanism for detecting whether or not a given topic map actually
> > contains a TMCL schema.

Yeah, I was also surprised to see it disappear. Happens when one
does not follow closely...

> Graham's reply was:
> 
> > We had the schema behind the scenes creation but removed it in Oslo.  
> > It was ugly/messy as it meant the constructors could only be used  
> > for constraints in one schema. If we consider schemas to be in the  
> > scope of a map, then reify the map and make annotations about it and  
> > runtime merge / virtually merge the schema topic map when needed.
> 
> I think we should consider this again. Here's what I think we should do:
> 
>   (1) define a topic type for TMCL schemas,

+1

>   (2) define an is-defined-by association type used to connect  
> constraints
>       and types with a schema topic,

+0.5 . I would prefer maybe another name, because constraints are not
really defined by the schema. "Hosted" maybe.

> This way the CTM templates do not provide explicit support for  
> connecting constraints with the schema (unless, that is, we decide to  
> add optional arguments to CTM templates). However, people can define  
> their own templates, and tools for creating schemas can create these  
> associations automatically.

Yes, users can handle the membership of a constraint _outside_ the
templates to instantiate the constraints.

> This gives people a way to talk about CTM schemas, which I think is  
> useful, and also a way to track what comes from which schema.

And it also allows to have an association "is-valid" between a schema
and a map. _That_ should be standardized, not?

> Thoughts, anyone?

Always a lot of thoughts :-)

\rho