Re: [xacml] conditions references in rules: xml to the rescue?

[Michiharu Kudoh <KUDO@jp.ibm.com>]

I think that using parsed general entities does not work when the policy
engine needs to use information about condition ID because the parsed
general entities are automatically replaced with the target entities when
generated in the memory. What it is useful is to check which condition is
identical with another condition. The engine can optimize the evaluation by
skipping the identical expression just by looking the condition ID attached
to the DOM fragment.

Michiharu Kudo


                                                                                                                                                    
                      "Simon Godik"                                                                                                                 
                      <simon.godik@over        To:       <xacml@lists.oasis-open.org>                                                               
                      xeer.com>                cc:                                                                                                  
                                               Subject:  [xacml] conditions references in rules: xml to the rescue?                                 
                      2003/06/12 17:45                                                                                                              
                                                                                                                                                    
                                                                                                                                                    



How to reuse complicated conditions in rules?

There is a simple way to do it with parsed general entities, both internal
and external.
As such, parsed general entities allow to reuse any part of the rule or
policy as long as entity is
well formed xml.

In this case, policy model is not broken and we get syntactic shorcut
without schema modifications.

Here is an example with external parsed general entity (internal parsed gen
entity is also possible)

Suppose we have parsed general entity in cond.xml:

<?xml version="1.0" encoding="..."?>
<Condition>
    <Apply FunctionId="...">
    </Apply>
</Condition>

Then in policy.xml:

<?xml version="1.0" encoding="..."/>
<!DOCTYPE Policy [
    <!ENTITY cond SYSTEM "cond.xml"
]>
<Policy xmlns:xacml="...">
<Rule ...>
    &cond; <-- entity reference
</Rule>
</Policy>

Simon