Hi again Rich,
There is one more problem. Not all XACML data types have a defined
equality function. So it wouldn't work in all cases.
Regards,
Erik
Erik Rissanen wrote:
> Hi Rich,
>
> I still think that a ID reference is simpler than digging up the
> datatype, attribute id and possibly issues, and going through all the
> attributes in the request section looking for nested elements
> containing matches for all two/three values.
>
> Also it's more verbose, making it more difficult to read by humans
> (for debugging, development, audit, etc) and means less data to move
> around.
>
> Regards,
> erik
>
> Rich.Levinson wrote:
>> Hi Erik,
>>
>> I see your point. How about if we constructed ListReference as follows:
>>
>> 1. Normal single element in category case:
>> * <ListReference Category="cat1"/>
>> 2. Multiple element in category case:
>> * <ListReference Category="cat2">
>> <Attribute AttributeId="xxx" Issuer="yyy"
>> DataType="datatype">
>> <AttributeValue>zzz</AttributeValue>
>> </Attribute>
>> </ListReference>
>>
>> With this approach typical case would be just match Category.
>> Multi-case would be match Category and contained Attribute w value.
>> Then Attr would only be synthetic in the extreme case as described in:
>> http://lists.oasis-open.org/archives/xacml/200901/msg00049.html
>>
>> Thanks,
>> Rich
>>
>>
>>
>> Erik Rissanen wrote:
>>> Hi Rich and all,
>>>
>>> This sounds good to me, except that I don't like the use of the
>>> synthetic id as the reference in the decision list. This forces all
>>> requests to contain synthetic ids, which I think are not needed in
>>> most cases, and is also more difficult to parse for a pre-processor
>>> since the id is more deeply nested.
>>>
>>> Regards,
>>> Erik
>>>
>>> Rich.Levinson wrote:
>>>> Hi Erik, Hal, and TC,
>>>>
>>>> There have been a lot of emails on this issue so far, but I think
>>>> we are at the point where all the ambiguities and potential missing
>>>> pieces have been accounted for, so I will try to summarize where I
>>>> think the proposal currently stands.
>>>>
>>>> First of all here are some reference emails that have examples that
>>>> show different aspects of the proposed solution:
>>>>
>>>> * example request with XPath (in Erik's most recent email (below))
>>>> which is purported to return multiple nodes (an example response
>>>> would be helpful to augment this:
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00053.html
>>>> * example request with decision lists (Hal's most recent email)
>>>> (ignore the CorrelationId, because as Erik showed, it will not
>>>> work w XPath)
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00051.html
>>>> * example request showing multiple <Attributes> elements having
>>>> same @Category and using "synthetic attribute" with
>>>> "...multiple-request:unique-id" (would be useful to have
>>>> corresponding response showing returned "disambiguated"
>>>> <Attributes> elements
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00049.html
>>>> * example response showing 5 distinct results, not using synthetic
>>>> attribute, but using "...resource:resource-id" for Result
>>>> correlation. (This shows the important concept that not only is
>>>> the <Attribute> with the @IncludeInResult returned, but also its
>>>> parent <Attributes> element with the @Category.)
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00045.html
>>>> * original example request w DecisionList and w follow-up minor
>>>> correction
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00015.html
>>>> o
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00035.html
>>>>
>>>> Based on the analysis that has been done, I have a few
>>>> recommendations that, at least to me, appear to be important enough
>>>> to itemize as suggestions for the specifications.
>>>>
>>>> For the 3.0 Core spec:
>>>>
>>>> 1. It became inferentially apparent that a fundamental "rule" is
>>>> that a Request context that is processed by the PDP must have at
>>>> most 1 <Attributes> element with a specific Category. I
>>>> recommend that this be explicitly stated in section 5.35 in the
>>>> description of the <Attributes> [One to Many] element. What is
>>>> there now is not unambiguous in this regard, and I recommend it
>>>> be tightened up.
>>>> 2. Similarly, I think explicit text should be in Section 5.37 for
>>>> the Category [Required] description. i.e. specify that while
>>>> multiple <Attributes> elements with the same Category are
>>>> allowed in the Request element, that for the purpose of making
>>>> an authorization decision, only one <Attributes> element per
>>>> Category is allowed.
>>>> 3. Section 5.39 under explanation of IncludeInResult [Default
>>>> false] I recommend that when included in Result the Attribute
>>>> will be parented by its <Attributes w @Category> element. Also
>>>> if multiple <Attribute> elements within one Category are tagged,
>>>> then they will share the parent.
>>>> 4. Section 5.41 under explanation of <Attributes> element, I
>>>> recommend that it be explicitly stated that there will be one
>>>> <Attributes> element for each @Category in the Request that
>>>> contained an @IncludeInResult.
>>>>
>>>> For the 3.0 Multi-Decision spec:
>>>>
>>>> 1. I recommend that at least for the multi-Attributes @Category
>>>> mechanism that a clear explanation be included that without
>>>> DecisionLists, that there is an inferential n-dimensional
>>>> cross-product applied, where n is the number of @Categories
>>>> that have multiple <Attributes> elements within the Request.
>>>> So, for example if there are 3 Category attrs, say cat1, cat2,
>>>> cat3 that occur in multiple <Attributes> elements, for example
>>>> let's say there are 4 <Attributes> elements w cat1, 4 with cat2,
>>>> and 3 w cat3, then there will inferentially be 4x4x3 = 48
>>>> individual Requests generated to the PDP, each of which will
>>>> have a Result element in the Response. It would also be worth
>>>> noting that if there are additional single element Category
>>>> attrs, say cat4, cat5, and cat6, that the <Attributes> element
>>>> for each of those Category attrs will be evaluated in all 48
>>>> decisions. i.e. all 48 decisions will be based on
>>>> cat1,cat2,cat3,cat4,cat5,cat6, where 4,5,6 remain constant thru
>>>> the process and 1,2,3 are incremented as if to visit every cell
>>>> in a 4x4x3 3-dimensional matrix in this particular example.
>>>> 2. I recommend that the DecisionLists mechanism be introduced as an
>>>> augmentation to the n-dimesional matrix in 1 above. i.e. given
>>>> the 48 decisions above, I think that DecisionLists can be used
>>>> to pare down the list so that the full n-dimensional cross
>>>> product does not get evaluated. i.e. The DecisionLists would
>>>> override the inferential processing if they were present.
>>>> * For example, if we really didn't want the 4x4 portion
>>>> above but were really interested in 2 2x2 portions, there
>>>> could be 2 DecisionLists up front that contained the
>>>> following elements:
>>>> o
>>>> cat11,cat12,cat21,cat22,cat31,cat32,cat33,cat4,cat5,cat6
>>>> o
>>>> cat33,cat34,cat43,cat44,cat31,cat32,cat33,cat4,cat5,cat6
>>>> * Each of the above DecisionLists would produce 2x2x3 = 12
>>>> results for a total of 24 results.
>>>> * i.e. the suggestion is that the presence of DecisionLists
>>>> simply override the inferential multiple effect of the
>>>> <Attributes> elements themselves and transfer the
>>>> inferential effect to the multiple category instances w
>>>> same category to within each list.
>>>> * i.e. the presence of the DecisionLists would effectively
>>>> say: regard the actual <Attributes> elements as a pool of
>>>> referencable entities and process the request as if
>>>> multiple Request elements had come in with <Attributes>
>>>> elements listed in the DecisionList, and process
>>>> inferentially on that basis. Everything would be returned
>>>> in a single response.
>>>> 3. The only lingering "annoyance" is that the DecisionLists address
>>>> the <Attributes> elements by the xml:id, whereas within the
>>>> inferential processing we need to reference for correlation
>>>> purposes based on an internal IncludeInResult attribute. This is
>>>> not a show-stopper of any sort, but it does appear that there
>>>> are 2 mechanisms effectively used to identify the same
>>>> <Attributes> element. A couple of considerations:
>>>> * It would seem that xml:id for <Attributes> elements that
>>>> only had a single instance is more than is needed since
>>>> one could theoretically simply identify these single
>>>> instance elements by identifying their Category value.
>>>> * It seems that what's needed for the DecisionLists that are
>>>> going to use multiple <Attributes> elements with the same
>>>> Category is something within the <Attributes> element that
>>>> distinguishes it from the other <Attributes> elements of
>>>> the same Category. This seems to be deja vu all over again
>>>> (sic) wrt the analysis that left us with the "synthetic
>>>> attributes" as the ultimate decider for those cases where
>>>> nothing else would work
>>>>
>>>> http://lists.oasis-open.org/archives/xacml/200901/msg00049.html
>>>> * Therefore, I am tentatively suggesting that a usable
>>>> alternative to URI,xml:id might be @Category.value(index),
>>>> where "index" would be the value of a synthetic attribute
>>>> within the <Attributes @Category> element with
>>>> AttributeId="...multiple-request:unique-id".
>>>>
>>>> I believe everything above, is essentially pretty much identifying
>>>> what has already been decided and putting it all in one place, at
>>>> least wrt 3.0 Core spec, plus I think that comment 1 for
>>>> multi-decision is simply stating what has already been agreed,
>>>> comment 2 is some clarification on how DecisionLists could be
>>>> viewed and used, and comment 3 admittedly is something "new" to
>>>> address what appears to me to be a lingering "rough spot" in what
>>>> has been decided so far.
>>>>
>>>> Comments and suggestions are welcome.
>>>>
>>>> Thanks,
>>>> Rich
>>>>
>>>>
>>>> Erik Rissanen wrote:
>>>>> Hi Hal,
>>>>>
>>>>> I just realized that the CorrelationId will not work, and we need
>>>>> the IncludeInResult.
>>>>>
>>>>> The existing 2.0 multiple resource profile defines a few more
>>>>> modes of multiple requests than multiple <Resource> elements. For
>>>>> instance, it is possible to specify multiple request in the form
>>>>> of an xpath expression on the <ResourceContent>, where each node
>>>>> the xpath matches will generate an individual request. Like this
>>>>> for instance:
>>>>>
>>>>> 2 <Request
>>>>> 3 xmlns="urn:oasis:names:tc:xacml:2.0:context:schema:os"
>>>>> 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>>>> 5 xmlns:md="http://www.medico.com/schemas/record"
>>>>> 6
>>>>> xmlns:xacml-context="urn:oasis:names:tc:xacml:2.0:context:schema:os"
>>>>> 7
>>>>> xsi:schemaLocation="urn:oasis:names:tc:xacml:2.0:context:schema:os
>>>>> 8 access_control-xacml-2.0-context-schema-os.xsd">
>>>>> 9 <Subject>
>>>>> 10 <Attribute
>>>>> 11
>>>>> AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-id"
>>>>> 12 DataType="http://www.w3.org/2001/XMLSchema#string">
>>>>> 13 <AttributeValue>Julius Hibbert</AttributeValue>
>>>>> 14 </Attribute>
>>>>> 15 </Subject>
>>>>> 16 <Resource>
>>>>> 17 <ResourceContent>
>>>>> 18 <md:record>
>>>>> 19 <md:patient_info>
>>>>> 20 <md:name>Bart Simpson</md:name>
>>>>> 21 <md:age>60</md:age>
>>>>> 22 <md:sex>male</md:sex>
>>>>> 23
>>>>> <md:health_insurance>123456</md:health_insurance>
>>>>> 24 </md:patient_info>
>>>>> 25 <md:diagnosis_info>
>>>>> 26 <md:diagnosis>
>>>>> 27 <md:item type="primary">Gastric
>>>>> Cancer</md:item>
>>>>> 28 <md:item type="secondary">Hyper
>>>>> tension</md:item>
>>>>> 29 </md:diagnosis>
>>>>> 30 <md:pathological_diagnosis>
>>>>> 31 <md:diagnosis>
>>>>> 32 <md:item type="primary">Well
>>>>> differentiated adeno carcinoma</md:item>
>>>>> 33 </md:diagnosis>
>>>>> 34 <md:date>2000-10-05</md:date>
>>>>> 35 <md:malignancy type="yes"/>
>>>>> 36 </md:pathological_diagnosis>
>>>>> 37 </md:diagnosis_info>
>>>>> 38 </md:record>
>>>>> 39 </ResourceContent>
>>>>> 40 <Attribute\r
>>>>> 41
>>>>> AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id"
>>>>> 42 DataType="http://www.w3.org/2001/XMLSchema#string">
>>>>> 43
>>>>> <AttributeValue>*[local-name()='Resource'][namespace-uri()='urn:oasis:names:tc:xacml:2.0:context:schema:os']/*[local-name()='ResourceContent'][namespace-uri()='urn:oasis:names:tc:xacml:2.0:context:schema:os']/*[local-name()='record'][namespace-uri()='http://www.medico.com/schemas/record']/*[local-name()='patient_info'][namespace-uri()='http://www.medico.com/schemas/record']/*[self::*[local-name()='name'][namespace-uri()='http://www.medico.com/schemas/record']
>>>>> or
>>>>> self::*[local-name()='age'][namespace-uri()='http://www.medico.com/schemas/record']]/descendant-or-self::node()</AttributeValue>
>>>>>
>>>>> 44 </Attribute>
>>>>> 45 <Attribute
>>>>> 46
>>>>> AttributeId="urn:oasis:names:tc:xacml:1.0:resource:scope"
>>>>> 47 DataType="http://www.w3.org/2001/XMLSchema#string">
>>>>> 48 <AttributeValue>XPath-expression</AttributeValue>
>>>>> 49 </Attribute>
>>>>> 50 </Resource>
>>>>> 51 <Action>
>>>>> 52 <Attribute
>>>>> 53
>>>>> AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id"
>>>>> 54 DataType="http://www.w3.org/2001/XMLSchema#string">
>>>>> 55 <AttributeValue>read</AttributeValue>
>>>>> 56 </Attribute>
>>>>> 57 </Action><Environment/></Request>
>>>>>
>>>>> From this request there will be multiple results, but there is
>>>>> only one <Resource> element. Each result will contain a specific
>>>>> ResourceId XML attribute for correlation purposes.
>>>>>
>>>>> In the corresponding 3.0 multiple request, it will be necessary to
>>>>> use the IncludeInResult since there are not multiple Attribute
>>>>> elements, which could be used for correlation, even if they had a
>>>>> CorrelationId.
>>>>>
>>>>> So I think we should drop the CorrelationId proposal, and if
>>>>> necessary, people will have to use a synthetic XACML attribute for
>>>>> correlation.
>>>>>
>>>>> Best regards,
>>>>> Erik
>>>>>
>>>>>
>>>>> Hal Lockhart wrote:
>>>>>> As of today's meeting I believe we are down to deciding how to do
>>>>>> correlation. The alternative previously proposed is to use the
>>>>>> IncludeInResponse mechanism. This may involve submitting
>>>>>> synthetic attributes, not referenced by policy, simply to
>>>>>> correlate requests and decisions.
>>>>>>
>>>>>> The new idea (at least to me) is to move my previously proposed
>>>>>> XML Attribute - CorrelationID - to the <Attributes> element
>>>>>> instead of having it in the <DecisionList> element.
>>>>>>
>>>>>> This seems clearer to me, but others should express their
>>>>>> opinions. The new scheme would look something like this:
>>>>>>
>>>>>> <Request>
>>>>>>
>>>>>> <DecisionLists>
>>>>>>
>>>>>> <DecisionList>
>>>>>>
>>>>>> <ListReference URI="Sub1"/>
>>>>>>
>>>>>> <ListReference URI="Env"/>
>>>>>>
>>>>>> <ListReference URI="Res1"/>
>>>>>>
>>>>>> <ListReference URI="Act1"/>
>>>>>>
>>>>>>
>>>>>> </DecisionList>
>>>>>>
>>>>>>
>>>>>> <DecisionList>
>>>>>>
>>>>>> <ListReference URI="Sub1"/>
>>>>>>
>>>>>> <ListReference URI="Sub2"/>
>>>>>>
>>>>>> <ListReference URI="Env"/>
>>>>>>
>>>>>> <ListReference URI="Res2"/>
>>>>>>
>>>>>> <ListReference URI="Act2"/>
>>>>>>
>>>>>> </DecisionList>
>>>>>>
>>>>>>
>>>>>> <DecisionList>
>>>>>>
>>>>>> <ListReference URI="Sub3"/>
>>>>>>
>>>>>> <ListReference URI="Env"/>
>>>>>>
>>>>>> <ListReference URI="Res1"/>
>>>>>>
>>>>>> <ListReference URI="Act2"/>
>>>>>>
>>>>>> </DecisionList>
>>>>>>
>>>>>>
>>>>>> <DecisionList ... >
>>>>>> ...
>>>>>>
>>>>>> </DecisionList>
>>>>>>
>>>>>>
>>>>>> </DecisionLists>
>>>>>>
>>>>>>
>>>>>> <Attributes Category="Access_Subject" XML:Id="Sub1"
>>>>>> CorrelationId="FirstSubject">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>> <Attributes Category="Intemediary_Subject" XML:Id="Sub2"
>>>>>> CorrelationId="SecondSubject">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>>
>>>>>> <Attributes Category="Intemediary_Subject" XML:Id="Sub3"
>>>>>> CorrelationId="ThirdSubject">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>> <Attributes Category="Environment" XML:Id="Env">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>> <Attributes Category="Resource" XML:Id="Res1"
>>>>>> CorrelationId="FirstResource">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>>
>>>>>> <Attributes Category="Resource" XML:Id="Res2"
>>>>>> CorrelationId="Secondresource">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>> <Attributes Category="Action" XML:Id="Act1"
>>>>>> CorrelationId="FirstAction">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>> <Attributes Category="Action" XML:Id="Act2"
>>>>>> CorrelationId="SecondAction">
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> <Attribute>
>>>>>> ...
>>>>>> </Attribute>
>>>>>>
>>>>>> </Attributes>
>>>>>>
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>
>>>>>> </Request>
>>>>>>
>>>>>>
>>>>>> Hal
>>>>>>
>>>>>>
>>>>>> ---------------------------------------------------------------------
>>>>>>
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>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> ---------------------------------------------------------------------
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>>>>>
>>>
>>>
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