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Subject: RE: [uddi-spec] Issue with Value Sets with entity keys as values


Title: RE: [uddi-spec] Issue with Value Sets with entity keys as values

Sorry, Sam, but I don't think I agree. I do not see that the tModels must be checked for the mapping to happen. Oh, it is a "nice to have" that the keys be genuine, but we can still cope even if they are not, surely? It is possible to identify whether a "key" is version 2 or version 3 by inspection, and there is an algorithm we can apply to convert in either direction, so we can convert a "key", even if it isn't genuine. Or have I missed something?

I am, however, increasingly of the mind that this particular functionality should not be "magic" (I really detest "magic"!)- that we do not want to have "magic" tModels that get special treatment for their values. I believe we should include (yes, as a change to V3 that will have an impact of V4) the ability to mark a tModel as "version-key-converting" (I'm open to a better name, though). Any such tModel will have all its values run through a filter on read and write, with appropriate conversions based on the API version of the request.

To add to my heresy, I wonder if this might not be better handled by adding an attribute to the tModel structure. Yes, it would be possible to identify tModels with this property by adding an entry to their category bag, but I suggest this because we already know this will require change to any UDDI server implementing it, and it may be simpler to implement the change if the server is checking for an attribute rather than for the presence of a particular tModel key in the category bag. We are asking the server to do some special processing of the values - it seems only reasonable not to pretend that this is some kind of "normal" addition.

I have to say that this problem feels like one part of the version 3 spec that is fundamentally broken, and if it requires an unpleasant change to fix it, I'd suggest we accept that unpleasant change, rather than painting over it and pretending that it's not a problem. I was not around when the decision was made to change the keying system from version 2 to version 3, but I think we are still dealing with the ramifications of that change.

Now excuse me while I crawl behind this handy concrete wall... I suspect I may get an "education" in the next little while :-)

Tony Rogers

 

-----Original Message-----
From: Wai-Kwong Sam LEE
To: John Colgrave
Cc: uddi-spec@lists.oasis-open.org
Sent: 1/05/2003 8:14 AM
Subject: Re: [uddi-spec] Issue with Value Sets with entity keys as values

John / Claus / Others,

I think if we go down the path of making the registry do the mapping,
UDDIv2
specification may need to be changed as well.

The scenario is, in order to allow the registry do the automatic mapping
of the
keyValue from v2 keys to v3 keys, the registry needs to know that the
keyValues
are indeed geniue entity keys, (similar to the case that the registry
needs to
validate that tModelInstanceInfo/@tModelKey is indeed a real tModelKey).

Currently, these tModels (defined in UDDI-WSDL TN, such as
portTypeReference)
are unchecked. They need to be made checked so that the registry can
reject
invalid keyedReferences (that do not reference to a real tModelKey).

Making these tModels checked is probably a good feature to begin with.
It can
reduce the likelihood of poor data and be consistent with the checking
behavior
of similar canonical tModels like owningBuinsess. But the catch is, we
need to
start doing it in UDDIv2.


A recap of the discussion so far:

1. owningBussiness_v3 approach
    - a burden to the publishers (or publishing app),
      who have to explicitly publish two keyedReferences: one for v2
      and one for v3.
    - in particular, a burden to publisher during v2-v3 migration
    - inquiry users /apps are not affected, as they know the
version-specific
      keys: both the categorization scheme tModelKey and the value sets
are
      version-specific.

2. make registry do the mapping, by categorizing these new tModels
    with an indication that the value set keyspace is UDDI entity keys
    - relieves the burden on publishers in approach 1
    - inquiry users / apps are again not affected, as in approach 1
    - some burden to registry implementation, potentially performance
concern.
    - need to change the v3 spec
    - need to change the v2 spec too, in my opinion.



- sam

John Colgrave wrote:
> Claus,
>
> I regard the current specification of owningBusiness_v3 etc. to be an
error
> as it has the same problems I described for the new Category Systems
in the
> WSDL TN.
>
> I quite agree that this will require a change to the V3 specification
and
> envisaged turning my e-mail into a Change Request for V3.  I saw this
as
> introducing another dependency of the WSDL TN on a V3 CR.
>
> Given/Assuming that the V3 spec. is in error then I think it is
appropriate
> to change the V3 spec. to add this extra Category System, describe how
a
> V2/V3 registry implementation must handle Category Systems that have
entity
> keys as values and remove the V3 versions of any affected Category
Systems.
>
> As you know, I do not regard this as a significant performance issue
as it
> is "just" another instance of multi-version key handling, but
triggered by
> categorization rather than static typing.  If people feel that this
feature
> will significantly impact UDDI performance they should certainly say
so but
> I think this feature is something that we have to have to make current
V3
> functionality usable, not to mention its critical importance to the
way that
> the WSDL TN would work in a multi-version registry, and so any
performance
> concerns would have to be weighed against that.
>
> John Colgrave
> IBM
>
>
> -----Original Message-----
> From: Von Riegen, Claus [mailto:claus.von.riegen@sap.com]
> Sent: 28 April 2003 08:39
> To: Anne Thomas Manes; uddi-spec@lists.oasis-open.org
> Subject: RE: [uddi-spec] Issue with Value Sets with entity keys as
values
>
> Separate tModels for V2 and V3 are necessary since the V3
specification by
> no means outlines a special handling of uddiKey-based value sets.
> I agree that it would be a good thing to have it - at least for the
users of
> a UDDI registry - but it would require at least
> - a specification of the special behavior for uddiKey-based value sets
in a
> multiversion registry
> - a canonical categorization of such value sets so that both the nodes
of a
> UDDI registry and UDDI users can programmatically discover when such
> behavior is to be applied.
>
> As a consequence, I don't see a possibility to introduce such a
behavior in
> a Technical Note. It would be possible if we change the V3
specification
> itself accordingly (including the currently built-in behavior for the
> "owningBusiness" and "validatedBy" value sets). However, there are at
least
> two
> issues this approach faces:
> 1) We decided to change the V3 specification for errors,
inconsistencies and
> ambiguities only. The proposed behavior is certainly a new feature.
Thus, we
> must have good reasons to introduce a new feature in a V3 errata.
> 2) While the proposed behavior certainly helps UDDI users, it puts
another
> burden on UDDI implementations, at least as far as the performance is
> concerned. I would like to see more feedback from other implementers
on this
> issue.
>
> Claus
>
> -----Original Message-----
> From: Anne Thomas Manes [mailto:anne@manes.net]
> Sent: Mittwoch, 16. April 2003 15:46
> To: uddi-spec@lists.oasis-open.org
> Subject: RE: [uddi-spec] Issue with Value Sets with entity keys as
values
>
>
> +1.
>
> Having different tModels for V2 and V3 won't work. The only viable
option is
> to use mapped keys.
>
> I'm not convinced that we need to create a new categorization, though.
I
> think we can get by with a new uddi-type ("entityTypeKeys" similar to
> "checked") - or perhaps a set of types that would allow us to specify
the
> type of entity key:
> - entityTypeKeys
> - businessKeys
> - serviceKeys
> - bindingKeys
> - tModelKeys
>
> Anne
>
>
>>-----Original Message-----
>>From: John Colgrave [mailto:colgrave@hursley.ibm.com]
>>Sent: Wednesday, April 16, 2003 5:25 AM
>>To: uddi-spec@lists.oasis-open.org
>>Subject: [uddi-spec] Issue with Value Sets with entity keys as values
>>
>>
>>The WSDL TN makes use of three Category Systems that have entity keys,
>>specifically tModel keys, as the valid values:
>>1) portType tModel reference
>>2) protocol categorization
>>3) transport categorization
>>
>>The valid values of these Category Systems are, deliberately, dynamic
and
>>depend on the registry content at the time that an entity is
>>published that
>>uses one of these Category Systems.  The valid values also depend on
which
>>version of the UDDI API is being used.  If a keyedReference is being
>>published using V2 then the valid values are the set of V2 entity
keys,
>>perhaps of one particular type such as tModel keys.  If a
>>keyedReference is
>>being published using V3 then the valid values are the
>>corresponding set of
>>V3 keys.  The valid UDDI entities are the same in each case, but
>>the type of
>>key that is used to refer to them is appropriate to the version
>>of the UDDI
>>API being used.
>>
>>These Category Systems are not compatible with the support for
External
>>Checked Value Sets.
>>
>>The WSDL TN was written (implicitly) assuming that the keyValue in
>>keyedReferences for these Category Systems would be mapped
>>between V1/V2 and
>>V3 in the same way that entity keys are mapped between versions
everywhere
>>else they are used.
>>
>>As an example, if a V2 application wanted to publish a binding
>>tModel for a
>>wsdl:binding that used the SMTP transport it would use the following
>>keyedReference:
>>
>><keyedReference tModelKey="uuid:4eeccd58-d3b0-3a6f-a466-9cce01cb1273"
>>keyName="V2 transport"
>>keyValue="uuid:93335D49-3EFB-48A0-ACEA-EA102B60DDC6"/>
>>
>>If, on the other hand, it were a V3 application that wanted to publish
the
>>same binding tModel, it would use the following keyedReference:
>>
>><keyedReference
tModelKey="uddi:uddi.org:wsdl:categorization:transport"
>>keyName="V3 transport" keyValue="uddi:uddi.org:transport:smtp"/>
>>
>>So far, so good.
>>
>>The issue is what happens when a V3 application retrieves a binding
tModel
>>that was published by a V2 application, or vice versa.  The WSDL
>>TN assumes
>>that both the tModelKey value and the keyValue are mapped as
>>appropriate so
>>that the application that retrieves the tModel sees exactly the same
>>keyedReference whether the keyedReference was saved by a V2
>>application or a
>>V3 application.
>>
>>This would appear to me to be a good thing.
>>
>>The suggestion made by Claus is to have separate V3-specific Category
>>Systems that can only have V3 keys as their valid values, and have the
>>original Category Systems only have V2 keys as their valid
>>values.  This is
>>similar to what was done with owningBusiness in V3.
>>
>>Note that both the "V2" and "V3" Category Systems would have both
>>V2 and V3
>>keys so they could each be used by both versions of the UDDI API but
the
>>application would have to know both the V2 key for an entity and the
>>corresponding V3 key for an entity, and both V2 and V3 applications
would
>>have to be written to know about both versions, which is a significant
>>difference.
>>
>>If an application were not written with knowledge of both
>>versions then if a
>>V2 application published the binding tModel as above and a V3
application
>>were to retrieve it, the V3 application would see a single
keyedReference
>>with a tModelKey that was the V3 key of the V2 Category System and a
>>keyValue that was the V2 key of a protocol tModel.  This V2 key would
be
>>meaningless to the V3 application.
>>
>>Conversely, if a V3 application published the binding tModel and then
a V2
>>application retrieved it, it would see a single keyedReference with a
>>tModelKey that was the V2 key of the V3 Category System, which it
>>would not
>>recognize as the V2 application was written without knowledge of V3,
and a
>>keyValue that was the V3 key of a protocol tModel.  This V3 key would
be
>>meaningless to the V2 application.
>>
>>The only way that I can see the "owningBusiness" approach working
>>is if the
>>applications take responsibility for dealing with the
>>multi-version issues.
>>
>>To continue the example, this would mean that an application that
>>published
>>a binding tModel would have to be aware of both the V2 Category System
and
>>the V3 Category System and publish two keyedReferences, one in each of
the
>>Category Systems so that the binding tModel could be used by both
>>V2 and V3
>>code.  I do not know how it is intended that V2 code can find the V3
key
>>corresponding to a V2 key or vice versa.
>>
>>Assuming that the binding tModel were published with both
keyedReferences,
>>then the code that retrieved the tModel would have to ignore one of
the
>>keyedReferences (the one using the "foreign" version) and use the one
that
>>matched its version of the UDDI API.
>>
>>There would be a migration issue as well as if the tModels were
originally
>>published in a V2-only registry then there is no way that the
V3-specific
>>keyedReference could be published, so when the registry were upgraded
to
>>support both V2 and V3, the extra keyedReferences would have to
>>be added to
>>each tModel before they could be used by V3 applications.
>>
>>I just can't see how to make this approach work, and that applies
>>to things
>>like owningBusiness that are already in V3 as much as the WSDL TN.
>>
>>The only way that I can see to allow for Category Systems, or
>>Value Sets in
>>general, that can take entity keys as values is to apply the
>>mapping to the
>>entity keys that are used in the keyValue attribute in the same
>>way that we
>>map entity keys everywhere else.  This is the only way that I can see
to
>>allow both V2 code and V3 code to know about only their own version of
>>entity keys and have interoperability/portability of registry content
>>across/between applications written to different versions of the UDDI
API
>>that access the same registry.
>>
>>As Tony pointed out, probably the best way to achieve this is to
>>categorise
>>such Value Sets with an indication that the valid values are UDDI
entity
>>keys, and the specific type of entity if that is known, as it is
>>in the case
>>of the WSDL TN.
>>
>>Such a categorization would have to be done via a new canonical
>>tModel that
>>was added to V3, and the new Category Systems etc. such as
>>owningBusiness_v3
>>would have to be removed from V3.
>>
>>John Colgrave
>>IBM
>>
>>
>>
>
>





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