OASIS Emergency Management TC

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Re: [emergency] EM brouhaha (aka Issue #26)

  • 1.  Re: [emergency] EM brouhaha (aka Issue #26)

    Posted 12-30-2003 14:45
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    Subject: Re: [emergency] EM brouhaha (aka Issue #26)


    On Thu, 2003-12-18 at 14:52, Rex Brooks wrote:
    > So, now I have to change my mind publicly and say that I think it 
    > should stay "qualified" so that locally cited elements have to 
    > validate against the CAP Schema. 
    
    I did some reading, and this is actually not the issue - whether it
    validates or not that is. The validation of the document is independent
    of the qualification. However, this does change "how" it is/would be
    validated, so it would impact how an instance document would be written.
    Here are the places I reviewed. The second one should really help if you
    read through the entire thread (4 messages):
    
    * http://www.w3.org/TR/xmlschema-0/#NS
    *
    http://lists.w3.org/Archives/Public/www-xml-schema-comments/2001AprJun/0169.html
    
    Let me see if I can explain my understanding.
    
    Couple of things first...just to make sure we are on the same page.
    
    1. XML Schema allows you to define more than 1 root element. For
    instance, we could have defined both <alert> and <status> on the same
    top level. As it stands, <status> is a child of <alert>. 
    
    2. These top level element (or attribute) definitions are called
    "Global", while child elements are called "Local" - as you reference in
    your email.
    
    3. XML Schema also allows you to import definitions from other schemas.
    To help bring us together on this, reference the conversations we have
    had about this in regards to a longer term definition of incident types
    for example, where we define the types in one schema, and import them in
    to all of our efforts. Benefit is that you only define in 1 place,
    rather than across multiple.
    
    When elementFormDefault="qualified", this basically means you either
    have to explicitly qualify each element using a namespace prefix for all
    elements, such as first including
    xmlns:cap="http://www.incident.com/cap/1.0"; where you would then see
    things like <cap:status>, OR you can implicitly qualify all elements by
    providing a default namespace on the uppermost element (<alert> in our
    case) in the instance document - ie:
    xmlns="http://www.incident.com/cap/1.0"; where you would just see
    <status>.
    
    It appears to me qualification basically controls how an author of an
    instance document would expect the document to be validated when there
    are either 1) multiple global elements or attributes are defined, OR 2)
    there is another schema imported. So, in regards to CAP 1.0, which only
    has 1 global element (<alert>) and does not import, I would propose we
    address the comment by simply adding something like the following -
    maybe in the Implementation Notes section (3.3):
    
    "In order to ensure the correct determination of the appropriate
    namespace in an instance document, and as defined in the schema in
    Section 3.4, all CAP elements MUST be qualified."
    
    Allen
    
    -- 
    R. Allen Wyke
    Chair, OASIS Emergency Management Technical Committee
    http://www.oasis-open.org/committees/emergency
    
    


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