18 Conformance, extensions

[Patrick Durusau <patrick@durusau.net>]

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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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