For example, if I had a rule which requires adaptation based on users:
<property name="user-id" matches="staff">
<action>some.adaptation.service</action>
</property>
There is no way I can pass the actual user-id, say "staff.foo" to the
adpatation service.
Initially, we assumed that the action element would hold a service
URL, in which case it would have been possible to add the parameter to
the URL, e.g.
<action>http://some.adaptation.com/service?user-id=staff</action>
However, given that we no longer assume a URL in the action element
(i.e. no early service binding), we probably have to add ways allowing
specification of parameters or meta-data in general (which would also
me more flexible than the restricted "?" syntax). Maybe a possibility
would be to allow specific parameter/value pairs within the action
element, e.g.
<action>
some.adaptation.service
<parameter name="user-id">staff</parameter>
</action>
or something like that... We plan to extend the action element anyway
to allow for specification of failure actions.
That's a great idea. But it still requires that the parameter value to be
passed to the service, either by URL or otherwise, be known at the time the
rule was written (using your example, it was known before hand that the
paremeter "user-id" is going to hold the value "staff").
My understanding of Hilarie's term "late binding" was to provide a way in
which the rule engine can substitute parameter value at run time. For
example, the current mechanism (and the example above) does not allow
dynamic properties like "system-load" to be passed to the adaptation
service.
-Markus