Re: WG "resolution" of the versioning/forwards-compatibility issue

thx for the summary, much appreciated.

J

On Thu, Oct 22, 2009 at 6:51 PM, Norman Walsh <ndw@nwalsh.com> wrote:
> Folks,
>
> At the XProc telcon today[1], we adopted most of the proposal[2] that
> I made for versioning. The most substantial change that we made was to
> reject the part of the proposal that allowed for unknown step types to
> occur in p:when or p:try/p:group elements.
>
> The persuasive arguments as I heard them were:
>
> * It's not clear that the algorithm proposed would handle every
>  conceivable kind of change that might occur. It's possible that some
>  future change could lead to the algorithm for dealing with "invalid"
>  steps to introduce unexpected or indeterminate changes to the flow
>  graph. Some members of the WG fear that that may already be the
>  case, the failing to do static analysis could lead to unexpected,
>  "incorrect" behavior.
>
> * What's more, it only works for pipelines where the author has
>  explicitly set out to handle the versioning problem by using
>  p:choose or p:try. Given that we have another mechanism, use-when,
>  which can also be used to explicitly handle the versioning problem
>  in a way that can't introduce any sort of indeterminacy, it seems
>  unnecessary to support the more complex behavior described.
>
> In short: an unknown step type in the XProc namespace (after use-when
> processing) is a static error. Unexpected port names *are not* an error,
> and are handled with the defaulting I proposed.
>
> Other changes/decisions:
>
> 1. The version attribute is only allowed on p:library, p:declare-step,
>   and p:pipeline.
> 2. Pipelines are no longer allowed to import declarations for step types
>   in the XProc namespace
> 3. The use-when attribute is just an ordinary attribute with no special
>   semantics when it occurs as the descendant of p:inline
>
> The editor has been directed to produce a new draft which reflects
> these decisions. If accepted by the WG at the next meeting, it will
> become the official position of the WG and will be published as a new
> *LAST CALL* working draft :-(. We'll go through the shortest possible
> LC and CR periods allowed. Readers are discouraged, but cannot be
> forbidden, from commenting on decisions not explicitly reopened by
> this LC draft.
>
>                                        Be seeing you,
>                                          norm
>
> [1] http://www.w3.org/XML/XProc/2009/10/22-minutes
> [2] http://lists.w3.org/Archives/Public/public-xml-processing-model-comments/2009Oct/0074.html
>
> --
> Norman Walsh <ndw@nwalsh.com> | Mankind are always happy for having
> http://nwalsh.com/            | been happy; so that if you make them
>                              | happy now, you make them happy twenty
>                              | years hence by the memory of
>                              | it.--Sydney Smith
>

Received on Thursday, 22 October 2009 21:02:23 UTC