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1.3 Metadata should be reusable in v2.x. SPs will continue to use SAML 1.1 protocol. Do not advertise new features (for ex, SAML 2 end points). Get the new version working for few days and then start rolling out new features of 2.x software.
How will you push metadata/AFP changes and refresh them frequently? How will you keep up with InCOmmon metadata changes? It was not seamless in early versions of IdP2 (when I started). We pushed changes during non-peak hours. It probably gotten better in the new release.
ePTID
Our 1.3 implementation was buggy. We took a chance and implemented standard algorithm. No one complained so far.
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