Subject Re: mari plan & next steps
From Peter Schober <peter.schober@xxxxxxxxxxxx>
Date Wed, 29 Oct 2014 16:06:24 +0100

* Leif Johansson <leifj@xxxxxxxx> [2014-10-29 15:48]:
> Experience from SPs that have begun to suck at the fire hose of
> interfederation seems to be that as the number of federations grow, the
> list of RequestedAttribute elements grow to the union of what is needed
> to fulfil the recommendations and practice of all federations.
> At best this violates the minimality principle and at worst causes
> breakage since the RequestedAttribute practice of one federation is
> often incompatible with that of the next federation. Experience shows
> that breakage occurs after only a small number of connected
> federations (I have example breakage at <3 federations).

I'd be interested in more (any, really) concrete examples of that kind
of breakage, to substantiate the claim of the massive scope of that
problem.  (I'm probaby just lacking that experience, and imagination.)

> The reason the problem occurs is that federations don't agree on the
> semantic and use of attributes. Furthermore it seems unlikely that
> we'll be able to align attribute semantics globally.

Personally I'd very much prefer to tackle harmonization and alignment
(possibly at the same time, given concrete problems to chew on) as
doing that would also solve the problem for the SP, which in the
proposal still is stuck having to deal with all the incompatible crap
that seems to be floating around, as you acknoledge:

> Under this scheme the SP will have to be able to handle a large
> number of alternative ways to represent "name" but this is already
> the case and is unlikely to change no matter what we do.

Best regards,