[mdx] MDQ questions

[Tom Scavo]

On Mon, Nov 25, 2013 at 1:31 PM, Ian Young <ian at iay.org.uk> wrote:
>
> On 25 Nov 2013, at 18:05, Tom Scavo <trscavo at gmail.com> wrote:
>
>>> The first question is: What value is that '+' operator delivering, in terms of enabling actual use cases?
>>
>>> If we have an answer to that, I'd like to capture it. If we *don't* have an answer to that, my alternative is to strike it and instead just have a single term. It's better to sweep away the complexity, in my view, if we don't actually need it.

I'm okay with sweeping it all under the rug, as long as we admit it
may come back to haunt us at a later date. Indeed, I would much rather
do that than use the '+' operator inappropriately.

>> I don't think that's possible with sweeping away a bunch of
>> functionality at the same time.
>
> True. Is it functionality anyone will ever deploy, though? I'm willing to be convinced, but at present I'm not seeing it.

I'm not sure I like playing this game since you can counter any
hypothetical example I cook up. If set algebra were not useful, why do
we see it just about anywhere we look?

My previous example was weak since it involved a characteristic of a
specific entity type (IdPs). Any characteristic of arbitrary entities
(IdP or SP) will do. Sections 2.4.1 and 2.4.2 list a boatload of such
characteristics:

- support SAML1?
- not support SAML2?
- expired?
- stale?
- has a signing key?
- has an explicit key whose size is at least 2048 bits?
- supports inbound artifact resolution?
- supports SLO?

plus a host of extension elements just waiting to be invented.

Tom