[emergency-msg] Review of CAP Issue # 13

["Tom Merkle" <TMerkle@capwin.org>]

ISSUE: 13 - Concern about validity of the XML Schema.

 

DESCRIPTION: The normative XML Schema in the CAP specification is improperly defined and will either generate validation errors or be rewritten to a form which conforms to XML Schema when input to common XML Schema processing tools. A major source of the problems is the fact that what should be anonymous simple types in the CAP schema are encoded with "name" attributes and are thus not anonymous. For instance, the CAP schema defines the element msgType as:

 

<element name = "msgType">

  <simpleType name = "msgType" >

    <restriction base = "string">

    ...

    </restriction>

  </simpleType>

</element>

 

A proper definition of the msgType element would *not* include the "name" attribute in the "simpleType" element. Thus, the proper definition would be:

 

<element name = "msgType">

    <simpleType>

      <restriction base = "string">

      ...

      </restriction>

    </simpleType>

</element>

 

   This improper use of XML Schema occurs at least 10 times in the CAP schema (I may have missed a couple...)

    Given that most well written XML Schema processors will rewrite or reject the normative CAP schema, it is hard to understand the justification for proposing a standard that contains a flawed normative definition. In this case, for interoperability to be had, it is necessary to assume that all XML Schema processors will either ignore or rewrite the offending elements of the schema in a consistent manner. While this appears to be the case so far, it introduces a risk of interpretation that is not appropriate for a standard such as CAP. For a standard such as CAP, it must be recognized that misinterpretations of CAP messages can lead to life-or-death consequences. Such a standard should only be accepted if it has achieved the highest possible levels of clarity and quality.

http://lists.oasis-open.org/archives/emergency-comment/200403/msg00020.html

 

 

PROPOSED CHANGE:  Ensure CAP meets the syntax as specified in the W3C XML 1.0 (Third Edition) (http://www.w3.org/TR/REC-xml/#sec-well-formed )

 

DISCUSSION: The current CAP 1.0 was corrected for syntax and structure issues before release.

 

RECOMMENDATION:  Close issue - no action taken

 

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