re: [cgmo-webcgm] [POLL] Re: Don's question

[Lofton Henderson <lofton@rockynet.com>]

Okay, everyone who has expressed a preference has opted for #2.

I will list this as the proposed resolution, and we will confirm in a 
telecon (formally, it needs to be confirmed in the WG now).

-Lofton.

At 05:10 PM 1/27/2009 -0600, Don wrote:
>Lofton,
>
>I prefer #2.
>
>It's easier to code (less verbose) for users and also to decode in the viewer.
>
>Don
>
>  >  All --
>
>  >  This is a straw POLL -- please respond, everyone.
>
>  >  We have sorted out and all agree that dashLength is a sub-element in
>  >  current ACI specs.  In discussion with Dave, we have discovered that a
>  >  slight deviation crept into the ACI chapter between 1st CD and 2nd CD
>  >  (according to Dave).  He had the idea that dashLength would be a
>  >  repeatable element, with each occurrence carrying one integer.  So a
>  >  pattern of 3 solid segments and 3 gap segments would require 6 
> elements.
>
>  >  Hence the DTD content model says dashLength+.
>
>  >  Somehow, the cleanup and integration of the chapter came out with the
>  >  content of dashLength being a blank-separated list of integers
>  >  (WebCGMString list-of-number subtype).  But it still retained "+", which
>  >  obviously leads to a redundant formulation.
>
>  >  Dave proposes that we should choose between two possibilities:
>
>  >  1.) as originally designed:  one integer per dashLength element, and
>  >  dashLength+ in the content model.
>  >  or
>  >  2.) as a WebCGMString-list-of-number subtype -- allowing a list of
>  >  blank-separated integers -- within dashLength as an XML *attribute*.
>  >  (Dave says it may as well be an attribute instead of a one-occurrence
>  >  element in this case.)
>
>  >  ==========
>  >  POLL:  Do you prefer #1 (DC's original design), or #2 (like LCWD text
>  >  except XML attribute instead of XML element)?
>  >  ==========
>
>  >  Note A:  Dave points out one attribute of #1 is that it doesn't require
>  >  much parsing.  On the other hand, #2 requires some parsing, but that
>  >  list-of-number subtype was used in WebCGM 2.0, so implementations should
>  >  already have that capability.
>
>  >  Note B:  The same logic and POLL choices #1 and #2 apply to gapWidth and
>  >  lineTypeIndex, each of which must handle a variable-length list of
>  >  integers.
>
>  >  Note C: directionVectors is similar in some ways.  In CGM:1999 it is 4
>  >  numbers ("4SS").  Here, the DTD says that the directionVectors element
>  >  contains 4 sub-elements:  vectorX, vectorY, vectorX, vectorY.  Each 
> of the
>  >  4 vectorX/vectorY elements contains one #PCDATA (i.e., one number).  The
>  >  text preceding the DTD snippet seems contradictory, "The 4 numbers of
>  >  directionVectors are encoded in the format of the WebCGMString
>  >  List-of-number subtype."  (Well, I guess it could be list-of-number, with
>  >  list length "1".  So if you like #2, then directionVectors could 
> become an
>  >  XML attribute.  If you like #1, it would continue to be an element that
>  >  contains 4 sub-elements, each of which carries one number.
>
>  >  Threads:
>  >  http://lists.oasis-open.org/archives/cgmo-webcgm/200901/msg00056.html
>  >  http://lists.oasis-open.org/archives/cgmo-webcgm/200901/msg00069.html
>
>  >  Regards,
>  >  -Lofton.
>
>  >  At 02:07 PM 1/26/2009 -0800, David Cruikshank wrote:
>  >  I guess just put it to a poll.  My only reason for repeating the element
>  >  was to make it easier to parse, but if everyone already does it, it
>  >  doesn't make any difference.
>
>  >  Most of the arguments about element vs attributes center around
>  >  presentation applications and not database applications which is what 
> this
>  >  really is like.
>
>  >  thx..Dave
>
>  >  On Mon, Jan 26, 2009 at 1:44 PM, Lofton Henderson <lofton@rockynet.com>
>  >  wrote:
>  >  I vaguely remember some head scratching and trying to figure out what
>  >  "repeatable string" meant, and it was probably then that the list idea
>  >  came along.
>  >
>  >  Okay, where do we go with it now?  I don't have a strong opinion.  Shall
>  >  we ask the members?  [...]  Just call it a POLL and vote for one or the
>  >  other of your two options?
>
>  >  Btw, this also affects the other two similar items, and I guess the
>  >  directionVectors also (may as well be attribute).
>  >
>  >  -Lofton.
>
>  >
>  >  At 12:50 PM 1/26/2009 -0800, David Cruikshank wrote:
>  >  Yep, that wording happened between the `1st and 2nd CD.  It actually
>  >  happened after the f2f. when I was "winding down"..  the wording in the
>  >  1st CD the dash length was defined as and "element of the ACI is a
>  >  repeatable string that specifies a the length of each dash and gap in the
>  >  defined line pattern".  It was not originally intended to be a list.
>
>  >  I guess it doesn't really make any difference, but if it is a list, it
>  >  might as well be an attribute.  The only reason for making it an element
>  >  is the fact that it is repeatable and captures each value in the 
> sequence.
>  >  The same is truefor all of the similar elements.
>
>  >  I think the choices are 1) keep it as a list and make it an attriubte, or
>  >  2) leave it as an element and return the the original intent.
>
>  >  thx...Dave
>
>  >  On Mon, Jan 26, 2009 at 9:42 AM, Lofton Henderson <lofton@rockynet.com>
>  >  wrote:
>  >  Dave,
>
>  >  Do you want me to archive the below message also?  Or wait till you 
> have a
>  >  look at Ch.9
>
>  >  Have a look not only at dashLength, but also gapWidth and lineTypeIndex,
>  >  which are also variable-length lists of numbers.  (For which I we might
>  >  have invented the @@List-of-number@@ subtype -- can't remember if it
>  >  already existed or not.)
>
>  >  directionVectors is also a list-of-number, but always 4  numbers.
>
>  >  [1]
>  > 
> http://www.w3.org/Graphics/WebCGM/drafts/current-editor-21/WebCGM21-Config
>  >  .html#ACI-dashlen
>
>  >  I agree that we could do away with "+" if we want to keep the
>  >  list-of-number -- that is a datatype that exists in 2.0 (I just checked),
>  >  so everyone has implemented it.
>
>  >  Or we could keep the "+" and say what happens with multiple occurrences
>  >  ("last wins" or "accumulate").  But that doesn't really add any
>  >  functionality, so I would opt towards simplicity:  one way or the other,
>  >  not both.
>
>  >  Btw, I'm not sure if this happened in your original draft, or on the 
> other
>  >  hand whether I introduced it when integrating and making the language
>  >  uniform.
>  >
>  >  -Lofton.
>
>  >
>  >  At 08:40 AM 1/26/2009 -0800, David Cruikshank wrote:
>  >  Let me go back and read what's in Chap 9.  The intent was the each
>  >  occurrence of dashLength contain a single integer and that you would just
>  >  multiple occurrences to define the pattern.
>
>  >  I can live with putting the whole string into a single occurrence, but
>  >  then you want to remove the "+" off the model because it no longer makes
>  >  any sense.
>
>  >  I'll take a look and formulate a response later today.
>
>  >  Dave
>
>  >  On Sun, Jan 25, 2009 at 4:24 PM, Lofton Henderson <lofton@rockynet.com>
>  >  wrote:
>  >  Dave,
>
>  >  I think you missed Forrest's later message about this:
>  >  http://lists.oasis-open.org/archives/cgmo-webcgm/200901/msg00057.html
>
>  >  He pointed this out:  dashLength is a sub-element of lineEdgeTypeDef.
>  >  I.e., it is an element in the content model of lineEdgeTypeDef.  Forrest
>  >  is correct, according to the DTDs.  Therefore, dashLength should precede
>  >  the close tag of lineEdgeTypeDef.
>
>  >  That aside, I agree that it is a matter of taste whether to make things
>  >  attributes or elements.  I'm not one (XML expert), but I understand that
>  >  XML experts fight religious wars about element-or-attribute.  Myself, I'm
>  >  content to live with your choice (or any other).
>
>  >  However, there is another issue to clarify
>
>  >  It [2] says: "The dashLength element is a string, in the encoding of the
>  >  ACI file, that contains a list of non-negative integers in the format of
>  >  the WebCGMString List-of-number subtype. The integers specify the lengths
>  >  of each dash andgap in the defined line pattern in abstract units, that
>  >  are then normalized as a whole pattern to the repeatLength attribute of
>  >  lineEdgeTypeDef. The first integer corresponds to solid, the second to
>  >  gap, the third to solid, etc."
>
>  >  That seems to clearly say that you can put the whole sequence into the
>  >  CDATA content of one dashLength element.
>
>  >  So this raises a new issue for clarification:  since the content model
>  >  says dashLength+, then what happens with 2 (or 3, or more) occurrences of
>  >  dashLength?
>
>  >  1.) last one wins;
>  >  2.) or, the integer list accumulates.
>
>  >  Your example (below) would suggest #2.
>
>  >  Thoughts?
>
>  >  (I'll redirect your answer if you like.)
>
>  >  -Lofton.
>
>  >  [1] http://lists.oasis-open.org/archives/cgmo-webcgm/
>  >  [2]
>  > 
> http://www.w3.org/Graphics/WebCGM/drafts/current-editor-21/WebCGM21-Config
>  >  .html#ACI-ledtdef
>
>  >
>
>  >
>  >  At 05:12 PM 1/25/2009 -0700, David Cruikshank wrote:
>  >  [...redirected to TC list by Lofton...]
>
>  >  I can't respond to the TC email list, so I'm sending my response this 
> way.
>
>  >  Don asked about the content model for the aci:
>
>  >
>
>  >
>
>  >
>
>  >  I'm directing this question to you since you created the ACI DTD and
>  >  perhaps could shed some light on this and at the same time confirm my XML
>  >  coding. dashLength is defined as an Element rather than as an 
> Attribute of
>  >  lineEdgeTypeDef, thus an example the the XML encoding I believe would be-
>  >  <webcgmConfig     <lineEdgeTypeDef lineIndex="1" repeatLength="100"
>  >  </lineEdgeTypeDef>     <dashLength>"10 2 5 2"</dashLength> 
> </webcgmConfig>
>  >  However it seems more natural for dashLength to be an Attribute 
> and  coded
>  >  like this: <webcgmConfig     <lineEdgeTypeDef lineIndex="1"
>  >  repeatLength="100"      dashLength="10 2 5 2"    </lineEdgeTypeDef>
>  >  </webcgmConfig> This also applies to the directionVectors and gapWidth
>  >  Elements assocaited with the hatchStyleDef. My response:
>
>  >  When things are repeatable, I've tended to make them repeating 
> elements as
>  >  opposed to attributes.  I think the correct encoding for your example is:
>
>  >
>  >  <webcgmConfig
>  >  <lineEdgeTypeDef lineIndex="1" repeatLength="100"
>  >  </lineEdgeTypeDef>
>  >  <dashLength>10</dashLength>
>  >  <dashLength>2</dashLength>
>  >  <dashLength>5</dashLength>
>  >  <dashLength>2</dashLength>
>  >  </webcgmConfig>
>
>  >  Remember dashLength is specified as "dashLength+".  That way no 
> parsing is
>  >  required to figure out the values.
>
>  >  If people want parse, it's ok but this was an attempt to simplify the
>  >  work.
>
>  >
>  >  Dave
>
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