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Subject: RE: [uddi-spec] Update to CR-034 (Creating self-referencing tModels)

Title: Message
I do appreciate the issues wrt th is in the face of 2-pass architectures, that said, a change in favour of rejecting self-referencing imposes additional validation requirements on single-pass implementations which otherwise do not have to perform this.
The out suggested is that we make this a "MAY" and registry policy (an absolute requirement in a registry replicating data between its nodes). I'm really not too keen making this a registry policy and would prefer making this normative behaviour. If we accept this, then we have a choice of picking between the needs of single-pass vs 2-pass architectures.
Let's discuss tomorrow.

From: Rogers, Tony [mailto:Tony.Rogers@ca.com]
Sent: Monday, July 07, 2003 21:54
To: Luc Clement; Von Riegen, Claus; uddi-spec@lists.oasis-open.org
Subject: RE: [uddi-spec] Update to CR-034 (Creating self-referencing tModels)

I believe we are all agreed about 2 and 3. The rub comes in 1, because it causes problems with 2-pass architectures vs 1-pass architectures.
A 2-pass architecture validates the entire content of the save operation, then executes it. That fits well with the requirement that the entire save fails if any element of it fails. Indeed, I thought this was the intended implementation while I was reading the standard initially.
A 1-pass architecture validates one item, then saves it, then proceeds to the next one, rolling the entire transaction back if there's a problem. That's all very well for those using a transaction-based storage system, but that's not a prerequisite that we should be placing on the implementor.
My strong preference is to forbid all internal references within a single save_ call - we have witnessed all manner of strange and horrible behaviours that must be specified if one permits references within the call. Things like: "what if someone saves a service under a different business after saving it under a first business, all in the one save_business call?".
Is there a real use case for allowing resaving within a single call? It seems to me that the only reason it's allowed is so we have a whole pile of problems to solve :-(
Tony Rogers
-----Original Message-----
From: Luc Clement [mailto:lclement@windows.microsoft.com]
Sent: Tuesday, 8 July 2003 14:37
To: Rogers, Tony; Von Riegen, Claus; uddi-spec@lists.oasis-open.org
Subject: RE: [uddi-spec] Update to CR-034 (Creating self-referencing tModels)

I have a problem making this a registry policy. I'm concerned about allow too many degrees of freedom in the spec when what the CR proposes is consistent with the spec today. To restate, given:

(1)     a tModel being saved refers to a tModel that is created earlier in the sequence of tModels

(2)     a tModel being saved (and created) refers to itself

(3)     a tModel being saved refers to a tModel that is created later in the sequence of tModels

The proposed solution (below) seems entirely reasonable and consistent with the rest of the spec in regards to the processing in document order principle (as well as satisfying the principle of least astonishment IMO).

Case (1) is allowed since tModels, like all other entities in save_xx API calls, are processed in document order.

Case (3) is not allowed since the tModel to which a keyedReference points to is to be saved at a later time. An E_invalidKeyPassed error must be returned.

Case (2) is not o.k. since it would otherwise require a special processing behavior. An E_invalidKeyPassed error message must be returned.

Luc Clément

From: Rogers, Tony [mailto:Tony.Rogers@ca.com]
Sent: Thursday, July 03, 2003 05:45
To: Von Riegen, Claus; uddi-spec@lists.oasis-open.org
Subject: RE: [uddi-spec] Update to CR-034 (Creating self-referencing tModels)

Perhaps we can avoid your discomfort with my suggestion by making the policy of whether to disallow references within the batch a policy that applies to the registry as a whole, rather than on a node-by-node basis.
Oh, on re-reading your comments, I see that you've suggested the same thing. :-)
Tony Rogers
-----Original Message-----
From: Von Riegen, Claus [mailto:claus.von.riegen@sap.com]
Sent: Thu 3/07/2003 20:59
To: uddi-spec@lists.oasis-open.org
Subject: [uddi-spec] Update to CR-034 (Creating self-referencing tModels)

I took an action item at our May 27 TC meeting to update CR-034 to meet the following requests:

"Claus took us through the description of this CR.  Tony would rather we disallow references to any tModels not already in the registry.  The problem here is that it imposes an extra check to do the saves in the registry.  A suggestion was made that we say nodes "MAY" allow (1), but now (2) or (3).  Things like service projections and hosting redirectors would be complicated as well. 

We agreed that the CR needs to be changed to get around the problem by saying that a node MAY permit (1), but MUST disallow (2) and (3).    There is also some confusion in the CR indicating the error condition as E_invalidKey.  It should be E_invalidValue, depending upon whether it's being used as the category, or as a value in the category.   Need to clarify.  Also note that the entire request may fail, saving the entities separately eliminates the problem.  A similar problem exists with hosting redirector. 

Should we create a recommended policy on which behavior the node supports?  Claus will suggest one. Claus will change the CR and resubmit."

After reviewing the CR and these requests again, I now believe that the requests lead to additional problems/questions.

1) Tony's suggestion that a node MAY disallow references to any tModels not already in the registry is not acceptable since this may result to a situtation where one node in a registry decides to allow such references and another decides to disallow them. If such data is replicated from the first node to the second, this would result in an unacceptable replication error.

As a result, two alternatives remain: either we decide that the behavior with regard to such references (allow or disallow them) MUST be specified on registry level or we decide that they are always allowed, that is, we stay with the currently specified (V3) behavior.

2) I don't recall why there was a discussion about including E_invalidValue as a possible error condition. A tModelKey in a keyedReference is always a tModelKey, and if it is invalid the E_invalidKey error condition applies. A tModelKey can certainly be used as a keyValue in a keyedReference (remember our discussion on value sets that are based on entity keys) but whether the key is valid or not is a matter of value set validation. This is specified in a separate section (5.2.3) and the corresponding error condition is already listed in section of the save_tModel API call section.

As a result, I don't see a need to update the specification in this regard.

3) Depending on the outcome of 1), we may even don't need a corresponding policy.

I'd be interested in differing opinions so that I can update the CR, if required.


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