Sanjiva -
I am in-sync with you about this. I was recently working with a group that was trying to create WS-Caching Policy using the policy framework. Briefly, they were trying to cache the responses from back-end services (long-running orchestrations) in the ESB layer for scalability and performance reasons. Their requirements were very similar to browser-cache in the sense, they wanted to define policies related to "time-to-live" for the cached response.
It might make sense to have standards around Caching Policy, Routing policies and as such infrastructaral policies ( as opposed to domain policies like charging, etc).
Thanks,
Naren
Naren
Sanjiva Weerawarana <[EMAIL PROTECTED]> wrote:
On Fri, 2006-08-11 at 17:39 +0200, Guy Crets wrote:
> Gervas,
>
> Very interesting post.
>
> Currently, WS-Policy remains limited to very low-level, technical
> details. I only know about WS-Security Policy and WS-RM Policy.
> Other characteristics of web services are hardly ever described with
> WS-Policy. E.g. availability, scheduled downtime, cost or
> charging, dependancy on other services or components, idempotency,
> references to older/newer versions of the service, ...
WS-Policy is a framework .. its not feasible for the framework to define
all the interesting domain specific policies. So for example take a cost
or charing policy - folks who are interested in that need to come up
with the domain assertions. WS-Policy just gives a (very simple really)
framework to say this-or-that and this-and-that type stuff along with
some rules on how to compose policies asserted at different
levels/places to form the final effective policy.
When SOAP first came out it was hammered hard especially by ebXML types
saying "it doesn't even have security" .. and of course that was by
design: SOAP too is just a minimalistic shell and the hard work was left
to others to do .. to specify what headers were interesting and what
they meant. WS-Policy is basically saying that actually those headers
are the realization of some domain specific policy and hence someone
needs to define policies for interesting domains like pricing and then
those can be combined in various interesting ways and placed in actual
messages. Of course for certain policies (e.g., privacy policies) the
actual policy may not have an on-the-wire ramification even.
So in some sense WS-Policy is the SOAP of the metadata world. Now the
hard work remains to agree on specific policy assertions for all the
interesting domain .. clearly more technopolitical wrangling lies
ahead :-).
Sanjiva.
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