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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: SDD again
> At 06:52 PM 5/8/98 -0700, alex@v... wrote:
> >No, it is not false. I hightlighted the word 'safe'. If you absolutely
> >*must* know that everything was read and interpreted correctly, you *must*
> >use a validating parser. There are many applications where this is not
> >an absolute requirement and, thus, you may use a well-formed parser.
>
> No. This claim is without technical merit and I cannot let it pass
> unchallenged. It is trivially possible to achieve correctness and 100%
> unquestioned reliability without the use of a validating processor. If you
> either (a) construct your DTD so that standalone='true' or (b) don't have
> external markup declarations, then you can have NO DOUBT WHATSOEVER that the
> document is being parsed correctly, for any sane denotation or connotation of
> "correctly". So please stop making this demonstrably false assertion.
Hmmm... nothing I am saying is asserting that you can't do (a) or (b).
I think the issue is one of verification. If I create an XML
document using an arbitrary DTD not authored by me, how do I know how to
create a standalone document without using a validating parser? It is the
only thing I have that allows me to check that I did everything correctly.
(Now, I could do this manually.... but please, what user of XML is going to
do that?)
Once I have used a validating parser and it passes the standalone=yes validity
constraint, I can then send it everywhere I please.... and it should work
just fine.
> Not only is your premise false in theory, it is vacuous in practice. If you
> think, for any real-world application, that its validation against some DTD
> guarantees "correctness" in any nontrivial sense, then I don't want to
> go anywhere near your software. Validity is a highly specific claim, one
> which is of great utility in many applications, but it does not equate to
> having "safety" or "correctness". Equally, lack of validity does not
> equate to lacking "safety" or "correctness".
I did not say this in any way. Validity as defined in XML and all the
"safety" or "correctness" that that allows you was only what I was implying.
Validity only raises the "comfort level" in which one operates. I can
*always* mis-use anyone's DTD at any point in time.
> >In addition, there are some applications that need some level of guarantee
> >about whether external declaration subsets will be read and honored. It is
> >this class of applications that we cannot address today with the current
> >definition of well-formed.
>
> This statement is correct, except for the unnecessary temporizing about
> "some level of guarantee". "Guarantee" is a binary condition; if you need
> a guarantee that the organization to which you are sending information
> will have external declarations read, then you need to specify the use of
> a validating processor at that end. If not, then not.
Yes. Which is something I have to do external to my document.... which is
quite fine with me.
> But please don't equate this particular guarantee with general concepts
> of "safety" or "correctness" - doing so gives the impression that the use of
> documents which are merely well-formed is in some way sloppy or irresponsible;
> such a claim is fatuous and very, very, very unhelpful.
Ah, now the issue. I am not implying this, and if I did, I certainly did not
mean to in any way. This, to me, is an issue of application of the concept
of well-formed documents. You must choose at what level you author and
processor your content at every step of the way.
For example, if you are working within a standardize industry or some
partnership-constrainted data transport, you had better use validating
processors on the creation and receiving ends. Once a *document* has
been identified to be valid, then you may use a well-formed processor.
If you are creating an ad hoc document, it seems to me to be
perfectly reasonable to only use a well-formed processor. No problem
here...
XML validity provides you some self-checks. It does not guarantee semantic
correctness--which is something I would *never* claim.
=============================================================================
R. Alexander Milowski alex@v... (612) 825-4132 v|e|o
MOS | sed s/SG/X/g > DYX
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