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18 Conformance, extensions

  • 1.  18 Conformance, extensions

    Posted 09-03-2013 16:00
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    Greetings!

    The final paragraph of 18 Conformance reads:

    *****
    This specification allows extensions. Each implementation SHALL fully
    support all required functionality of the specification exactly as
    specified. The use of extensions SHALL NOT contradict nor cause the non-
    conformance of functionality defined in the specification.
    *****

    First:

    "Each implementation SHALL fully support all required functionality of
    the specification exactly as specified."

    1) I assume at this point a conforming TOSCA implementation has been
    defined. Why would we say this again?

    2) Implementations cannot be constrained to conform to the TOSCA (or
    any other specification). If they fail to conform, then by definition
    they are not conforming TOSCA (or other) implementations.

    3) "...all required functionality..." and "...exactly as specified..."
    have no meaning. Conforming to the syntax and semantics as specified
    by sections does.

    4) SHALL doesn't help in conformance clauses unless you are defining a
    particular level of conformance. "All implementations that support
    capacity X, SHALL conform to provisions a - d, inclusive."

    Second:

    "The use of extensions SHALL NOT contradict nor cause the non-
    conformance of functionality defined in the specification."

    1) If extensions are used and they do make either a TOSCA Definitions
    document or a conforming implementation that processes TOSCA
    Definitions documents non-conformant ... I am not sure what this
    clause accomplishes?

    That is a TOSCA Definitions document or an implementation to process
    the same are free to become non-conforming at any point in time.
    That's part of the reason to have a specification. So we can detect
    when that happens and say: This is a non-conforming TOSCA Definitions
    document or a non-conforming implementation. That's the most we can do.

    2) Guessing but I think what was meant was:

    Extensions that make the syntax or semantics of a TOSCA Definitions
    document not conform to (reference to definition of conformance)
    render a TOSCA Definitions document invalid and such invalid TOSCA
    Definition documents (SHALL/SHOULD/MAY) be rejected by conforming
    TOSCA implementations.

    You could also say that such extensions are discarded automatically by
    a conforming TOSCA implementation.

    The SHALL/SHOULD/MAY + discard are all design decisions and I don't
    have any advice to offer. Really depends on how strictly you want to
    treat extensions.

    3) I would not say: "...the non-conformance of funtionality defined..."

    Mostly because "non-conformance of functionality" has no meaning.
    Conformance is to specific provisions of the specification and no
    vague references to what someone considers to be its "functionality."

    BTW, repeating it here would violate DRY as well.

    Hope everyone is having a great day!

    Patrick

    - --
    Patrick Durusau
    patrick@durusau.net
    Technical Advisory Board, OASIS (TAB)
    Former Chair, V1 - US TAG to JTC 1/SC 34
    Convener, JTC 1/SC 34/WG 3 (Topic Maps)
    Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
    Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)

    Another Word For It (blog): http://tm.durusau.net
    Homepage: http://www.durusau.net
    Twitter: patrickDurusau
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