There is quite a bite if text in SCA policy spec, section 3.4 for
example,  about using WS policy. One of the implications of this is
that WS policy can be used to defined policy alternatives within a
policy set. During wire validation I imagine that an alternative will
be chosen at the service based on the configuration of the reference.
Note that our code doesn't do this at the moment.

An implication of this is that we would have to provide as many
endpoints as there are policy alternatives in order that each
particular policy alternative is properly catered for and so that an
endpoint reference has something to match against. This is potentially
quite a few endpoints for cases of multiple policy sets with multiple
alternatives.

Also at the moment we activate each endpoint regardless of whether a
reference uses it. This it probably not ideal but we don't know what
external, non-SCA, clients are going to try and talk to the service so
it's difficult to rely on references alone. Following on from this,
policy alternatives may re-use resources such as URLs. If that is the
case we can't start all alternatives at the same time.

Just thinking aloud at the moment based on what I think the spec says.
Any comments, particular if you think I'm thinking about this in the
wrong way, are most welcome.

Regards

Simon
-- 
Apache Tuscany committer: tuscany.apache.org
Co-author of a book about Tuscany and SCA: tuscanyinaction.com

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