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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Namespace Mistake?
 > I don't believe you can assign two different namespaces the same prefix. You can if they are in different scopes. Fraser. On 10/10/2013, Bob Jolliffe <bobjolliffe@gmail.com> wrote: > Hi Tim > > I've no idea if this is best practice, but what I have done in the past > when I have minor (backward-compatible) modifications to a schema is keep > the namespace the same but also have a minorVersion attribute to allow > consumers to recognize the version, and keep namespace change for more > breaking changes. > > I don't believe you can assign two different namespaces the same prefix. > > Bob > > > On 10 October 2013 21:00, Timothy W. Cook <tim@mlhim.org> wrote: > >> Thanks for the prompt reply Gareth. >> >> Well, the schemas are not 100% compatible, that is why I version them. >> The use case is such that we do not want to convert the data from one >> version to another. It is for longitudinal healthcare records and this >> has >> been (and continues to be) a problem, especially when using SQL >> databases. >> The science changes over time but what was recorded at that point in >> time >> is what is important; forever. Including the semantic links that are >> embedded in RDF annotations in the schema. >> >> I understand that the URI is the namespace but when I use the same prefix >> to represent different namespaces, will that cause a problem? One other >> thing to note is that I use UUIDs for complexType and element names so >> any >> combination of prefix:element-name will always be unique, even though the >> prefix is the same. >> >> My question actually comes up because I am using MarkLogic and it won't >> allow me to define mlhim2 as a QName with two different namespaces. So, >> maybe it is only a MarkLogic limitation because of the way the database >> works? >> >> --Tim >> >> >> >> On Thu, Oct 10, 2013 at 4:49 PM, Gareth Oakes >> <goakes@gpslsolutions.com>wrote: >> >>> I'm not exactly sure of your use case so it is hard to comment, but just >>> to be certain: >>> >>> 1. Namespace is the URL, not the prefix. >>> 2. Prefix is a convenient shorthand for representing a certain >>> namespace. >>> 3. Namespaces know nothing of versioning. >>> >>> So could just as easily make your namespaces "http://apples" and " >>> http://autocannons", bind them to a: and b: respectively then use that >>> as a thought exercise :) >>> >>> If your database queries are not intended to be scoped by version, then >>> you might want to look at your schema versioning scheme. The "semantic >>> versioning" concept might be a good point of reference for that >>> activity, >>> eg. only bump up the version number in the namespace URL if your schema >>> update makes incompatible changes with the previous version of the >>> schema. >>> >>> In the case of incompatible schema updates, you might then want to make >>> a >>> conscious decision to either upgrade the entire database to the new >>> schema >>> or instead update all your query code to handle the new schema version >>> (this second option is what you question in your email below). The easy >>> (and slighty scary) option would be to just ignore namespaces. Hard to >>> recommend an approach without knowing more about the data and >>> application. >>> >>> It does occur to me however that if both the 2.4.1 and 2.4.2 schemas are >>> compatible with each other then it doesn't seem like a great idea to use >>> a >>> different namespace for each version as that will complicate the query >>> code >>> and any other downstream consumers of the XML. >>> >>> Just my 2c anyway, hope that helps? >>> >>> Gareth Oakes >>> Chief Architect, GPSL >>> www.gpslsolutions.com >>> >>> From: "Timothy W. Cook" <tim@mlhim.org> >>> Date: Thursday, 10 October 2013 8:34 PM >>> To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org> >>> Subject: Namespace Mistake? >>> >>> Hi All, >>> >>> I don't recall my specific reasons now but I have been reusing a >>> namespace prefix in schemas and instance data 'mlhim2' to reference >>> different versions of a schema reference model. >>> >>> For example: >>> xmlns:mlhim2="http://www.mlhim.org/xmlns/mlhim2/2_4_1" in one version >>> of the schema and instance data and then xmlns:mlhim2=" >>> http://www.mlhim.org/xmlns/mlhim2/2_4_2" in another version of the >>> schema and instance data. >>> >>> Now I think this is a mistake when I need to have multiple versions of >>> instance data in a single database and run queries across them. >>> >>> Should I change to start using: >>> xmlns:mlhim241="http://www.mlhim.org/xmlns/mlhim2/2_4_1" >>> and xmlns:mlhim242="http://www.mlhim.org/xmlns/mlhim2/2_4_2" >>> to be more explicit and avoid any problems? >>> >>> Thanks In Advance, >>> Tim >>> >>> >>> >>> -- >>> MLHIM VIP Signup: http://goo.gl/22B0U >>> ============================================ >>> Timothy Cook, MSc +55 21 94711995 >>> MLHIM http://www.mlhim.org >>> Like Us on FB: https://www.facebook.com/mlhim2 >>> Circle us on G+: http://goo.gl/44EV5 >>> Google Scholar: http://goo.gl/MMZ1o >>> LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook >>> >> >> >> >> -- >> MLHIM VIP Signup: http://goo.gl/22B0U >> ============================================ >> Timothy Cook, MSc +55 21 94711995 >> MLHIM http://www.mlhim.org >> Like Us on FB: https://www.facebook.com/mlhim2 >> Circle us on G+: http://goo.gl/44EV5 >> Google Scholar: http://goo.gl/MMZ1o >> LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook >> > 
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