[glue-wg] Answers to open questions

[Burke, S (Stephen)]

glue-wg-bounces at ogf.org 
> [mailto:glue-wg-bounces at ogf.org] On Behalf Of Donal K. Fellows said:
> In principle having a bunch of custom attributes is a reasonable thing
> to do (though it's an interop nightmare if you're not careful). But it
> is a proxy for subclassing, as that involves a statement that some set
> of attributes are meaningful together. I'm more concerned 
> about CSV as a
> format as it requires a completely different querying approach to the
> sort of thing that I'd expect to use with the rest of Glue2 (i.e. a
> language like SQL or XQuery). Not that I have a good answer; it's more
> of a "watch out here!" sort of thing. :-)

The point is that changing the schema is hard (so far we've managed two
updates in four years) so it's useful to have some generic way for
people to add extra things we haven't thought of. However, it's rather
limited (OtherInfo is just a string) so if someone wanted more structure
they would have to impose it themselves and have some way of
querying/parsing not supported in the basic schema. There is no
particular reason for it to be csv, that's just an example - I'm still
waiting for the first person to put XML in a GLUE string attribute! I
think subclassing is a bit of a red herring, for ldap at least there is
no way to change the schema at all without a large amount of effort -
certainly an individual site can't do it.

> You'd expose the strings to users? I wouldn't.

It depends what you call a user - at least people writing applications
will need to know the identifiers, and I regularly query the current
schema for particular service types just as an ad-hoc thing. We can have
complex structured type names if necessary, but it isn't clear why it
would be necessary.

Stephen