Metadata Distribution Subcommittee of TAC

[Ian Young <>]

On 16 Aug 2013, at 20:56, Tom Scavo 
<>
 wrote:

> Okay, so I should have said: an MDX server that supports arbitrary "ad
> hoc" queries (to use Scott's terminology) is a disaster waiting to
> happen.

I would agree with that assessment.  eduGAIN isn't one of those, though.

> I think we can avoid that and still offer some significant
> capability.

I agree.

> I can't speak for anyone else but it definitely *is* what I want to do
> since it fits my world view perfectly. That said, I'm not sure it
> needs to be represented in the spec at all.

OK, that simplifies things somewhat.  This would be the wrong place to 
discuss extensions to the metadata query spec anyway.

> So let me summarize my main points:
> 
> - An MDX server can avoid arbitrary "ad hoc" queries and still deliver
> significant functionality.

Definitely.

> - Can we agree that most everything of interest (> 80%) can be known
> in advance and can therefore be pre-computed?

For the use cases we've identified as ones we want to support so far, seems 
more like 100%.

> - Let users create entity attributes and thereby pre-register their
> queries (so that the target aggregate can be pre-computed).

It could be entity attributes, or it could in principle be some other 
selection mechanism.  The key part is that users pre-register their queries 
so that the response can be pre-computed and then served up from a can by the 
back end.

It also makes charging people who use the custom aggregate service a bit 
easier, no idea if that's on the cards ;-)

> - An online signing key (secured in a trusted HSM) is a separate
> issue.

Yes.

> From a security PoV, what we lose by exposing the signing key
> in an HSM might be gained by tightening the validity window and
> eliminating the human factor.

"Security" isn't scalar; you can't just trade off like that.  You need to 
decide which things represent actual threats you care about, and assess your 
defences against them independently.

        -- Ian

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