Fail on resolved RequestedAttribute isRequired=true

[Tom Scavo]

On Tue, Jul 14, 2015 at 10:03 AM, Cantor, Scott <cantor.2 at osu.edu> wrote:
>
> Nominally, the intent of saying something's required is in fact to tell the IdP that it may as well fail because the app won't run.

Yes, but what does it mean to say "the app won't run?" No one wants to
put up an error page, not the IdP nor the SP. The user experience
would be awful. So it seems to me: the IdP must respond, the SP must
handle the response, and a positive user experience must be salvaged.
Otherwise the federated model will be viewed as "broken."

> But we didn't implement that.

I'm glad :-)

As an aside, InCommon metadata doesn't support the isRequired XML
attribute on the <md:RequestedAttribute> element for this very reason.
The emphasis should be on providing a positive user experience, so
flagging an attribute as "required" serves no practical purpose.
Indeed, one could argue that if an attribute isn't required, it
shouldn't be in metadata in the first place.

Tom