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Subject: [ubl] version attribute - Re: [ubl] Minutes of Atlantic UBL TCcall2 November 2005
"Plus folk are rightly expecting minimal departure from the promises of the original NDR and confidence in UBL could perhaps be damaged if too much of the NDR1 is preserved in 2.0 (minor versioning would appear, by nature, to apply beyond UBL 1.0)." sorry I meant "damaged if too much of the NDR1 is NOT preserved in 2.0" Plus I'd add that not only would a UBL-specific version attribute be proprietary as far as software is concerned but that such an attribute would be specific to a particular version of UBL too (since it doesn't exist in UBL 1.0) so applications upgrading to UBL 1.0 have to be changed a lot to deal with 2.x and application designed for 2.0 might not work with 1.0 (not just semantically but mechanically). >>> "Stephen Green" <stephen_green@bristol-city.gov.uk> 04/11/05 16:18:32 >>> Objection regarding version attribute I'd refer to Eduardo and Arofan's excellent XML 2003 paper http://www.idealliance.org/papers/dx_xmle03/papers/03-04-03/03-04-03.pdf section 4 - first paragraph "The scope of UBL, and the potential for having several versions of the same schema extant at the same time, places emphasis on some particular aspects of versioning. First, the manageability of a versioned "package" becomes very important, because there is little or no control over the applications that use it. Users must be able to easily distinguish one version from another, and applications should be able to do the same, preferably without having to implement any functionality that is specific to one particular version. (It should be pointed out that, while XSD does offer us a "version" attribute on the schema element, there is no standard on how that field is to be used. Any versioning approach that relies on it, or similar other "version" attributes applied to various elements, is in essence proprietary.)" I agree that a UBL specific version attribute has a downside of being 'proprietary', too specific to UBL. It does allow the attribute to appear in an instance which improves on the xsd:version attribute, but is more proprietary and has to be catered for in software in a way that is specific to UBL. This may exacerbate the impact on other standards (like ebXML) and subsets (see my previous email today), not to mention customizations (which have to have a way to show they are a customisation of a particular minor version). Add to this the problem of derivation which needs a namespace different from the one importing it and I think there is a very strong argument for keeping the minor version number in the namespace in the case of UBL - and I see less of a reason for consigning it to a UBL-defined attribute. Then there is the problem that references to the value of the attribute have lack of precision of 'vocabulary' control (e.g. is '2.0' the same as '2:0' when version needs to be quoted outside of UBL). Plus folk are rightly expecting minimal departure from the promises of the original NDR and confidence in UBL could perhaps be damaged if too much of the NDR1 is preserved in 2.0 (minor versioning would appear, by nature, to apply beyond UBL 1.0). Even if we were to abandon substitution groups and derivation and deltas (unless these can be kept somehow without substitution groups in the mechanism), I'd still hope that we kept the minor version in the namespace (not least because it allows necessary precision if just the namespace and not the version can be referenced in trading partner agreements and business process specifications and likewise in customisations). All the best Steve >>> <jon.bosak@sun.com> 04/11/05 00:44:07 >>> MINUTES OF ATLANTIC UBL TC MEETING 16H00 - 18H00 UTC WEDNESDAY 2 NOVEMBER 2005 ADMINISTRIVIA It was decided at the close of this meeting that due to attendance at XML 2005, we will not be holding the Atlantic call 16 November. We *will* be holding this call at its regularly scheduled time next week (9 November). ATTENDANCE Jon Bosak (chair) Mikkel Brun Mavis Cournane Michael Grimley Betty Harvey Bryan Rasmussen Kumar Sivaraman Paul Thorpe STANDING ITEMS Additions to the calendar: http://ibiblio.org/bosak/ubl/calendar.htm None. Review of Pacific and Europe/Asia calls No comments. Schedule review Including attendance at April meeting in Brussels JB: This meeting is to be hosted by CEN/ISSS in Brussels the week of 24 April. It accidentally got dropped from the 2.0 schedule. We very much want to accept the offer to host, but neither JB nor TM will be available to chair. We need to know who can commit to be there. ACTION: JB to poll the TC for attendance at the April F2F in Brussels. ACTION ITEM REVIEW ACTION: JB to create the first draft of index.htm. Status: Done. ACTION: TC members visiting NYC in October or November to check out the Sun facilities and see whether they are suitable for a UBL TC meeting. JB will be coming through in mid-November and will also check then. Status: Pending. ACTION: JB to post a question on ubl-dev: What do other widely used schemas do about minor version namespace URIs? Status: Done. ACTION: Everyone involved in the development of the support pieces to give JB time estimates. JB: We have estimates for SBS from SG. We still need estimates for code lists, HISC, and the business process scenarios. ACTION: MB to check with PB regarding time estimates for the business process scenarios. FOR THIS MEETING NDR work session: Minor versioning. See http://lists.oasis-open.org/archives/ubl/200510/msg00084.html *** NOTE that as usual, voting members have a week to register any disagreement with the decisions described below. If no disagreement is registered, the decisions arrived at during the call will become officially adopted by the TC. *** Question 1: Should minor-version schemas only contain the deltas, or should everything be redeclared (with the 'ccts:Version' documentation component reflecting the version of individual types). Discussion: Deltas make clear exactly what's been changed or added and make it easy to determine backward compatibility. AGREED that minor-version schemas should only contain the deltas. Question 1.a: Should we have minor-version spreadsheets that only capture the deltas and their relationship to the major version? Discussion: Providing full spreadsheets for the minor version allows someone coming in at that stage to see the whole picture. It also sidesteps the problem of how to capture the relationship between major and minor at the spreadsheet level (we can just add a flag to mark the items that have been added in the minor version). AGREED that the minor version spreadsheets should contain the entire vocabulary, with a flag to indicate what has been changed or added in the minor version. AGREED that we thank Bill Burcham for his contribution of a method that could have been employed if we had decided that the minor version spreadsheets would contain only the deltas. Discussion: It may be difficult for tools to generate the deltas (see decision on Question 1 above) from the full spreadsheets. It's possible that the tool we use will only be able to create major version schemas, and that we will have to create the minor version schemas by hand. AGREED that while we hope that tools can be configured to create the minor version delta schemas from the full spreadsheets, we are willing to adopt this policy even if it means that the minor version schemas have to be created by hand. Question 2: Should the namespace name change for minor versions? How about the namespace prefix? Discussion: Our assumption is that a minor version of UBL may add new content but will not change the meaning of anything declared in the major version schemas. It therefore appears that the best approach is to separate semantic identity from versioning. But doing so will require us to specify expected behavior of UBL processors when presented with instances exhibiting different versioning information. AGREED that minor versions should use the same namespace as the major version from which they are derived (which means, for example, that the namespace for UBL 2.0 should reference "UBL 2" rather than "2.0") and that the version should be specified in a separate attribute TBD. AGREED that the namespace prefix stays the same in minor versions. ACTION: NDR editors to propose a suitable version attribute to be used by all UBL instances in time for discussion during the Atlantic TC call 9 November. ACTION: At the Manhattan F2F in January, NDR editors to develop a specification of expected behavior of UBL processors when encountering a version different from the one for which they were designed. (For example, UBL processors expecting a version 2.x when presented with an instance conforming to a later version 2.y might be required to attempt validation against the 2.x schemas and reject the instance if errors are found.) Discussion: We note that some users may not understand that the specification of namespace prefixes in our NDRs does not hardwire those prefixes in conformant instances. ACTION: At the Manhattan F2F in January, NDR editors to develop a best practice note for namespace prefixes. (For example, "For ease of comprehension it is recommended that the prefixes specified in our NDRs are used in instances, but applications must be able to process arbitrary prefix declarations per the XML Recommendation.") Question 3: What, specifically, determines whether a new version of the schema is actually a 'minor' or 'major' release? (If the schema only includes the deltas, and utilizes xsd:derivation concepts, the answer should be simpler than if the versioning is strictly model-based.) Discussion: We have already adopted the definitions given by Eduardo Gutentag in his message of 18 October 2005, but we note that his definition of backward compatibility transposes X and Y: c) backwards compatibility -- a schema X is said to be backwards compatible with a schema Y if documents that validate against schema X also validate against schema Y, and schema X follows (in time, or in version) schema Y. In other words, if all documents that validate against MySchema v1.0 also validate against MySchema v1.1, then MySchema v1.1 is said to be backwards compatible; but there is no expectation that any document that validates against MySchema v1.1 must also by necessity validate against MySchema v1.0 The example shows that the definition should read "and schema Y follows (in time, or in version) schema X." Question 4: Is (are?) Substitution Groups still on the table? AGREED: We will not use substitution groups for minor versioning. Question 5: What should be the normative version of UBL? Schema, Model or both. Discussion: XML inherits from SGML the doctrine that documents are normatively specified by the combination of formal declarations plus comments. Properly annotated schema formalisms such as DTD (W3C), XSD (W3C), RELAX NG (ISO), Schematron (ISO), and ASN.1 (ITU) are the standard mechanisms for establishing the validity of XML instances; no such standard exists for mechanically checking an instance against a model. And since there is no way of proving that a model and a schema describe exactly the same thing, we cannot say that both are normative. AGREED that UBL is normatively specified by the schemas plus associated normative prose. Jon Bosak Chair, OASIS UBL TC --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. You may a link to this group and all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. You may a link to this group and all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
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