[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: RE: Schema vs Schema-free (was: RE: XML Binary C
- Bob Wyman wrote: > Perhaps what is required here is the definition of a new facet > for at least one of these types that would flag the trailing zeros as > signficant. You can use a pattern facet on a float, double, or decimal in the same way you do on a string to enforce this sort of constraint. - Rich Salz wrote: > This is wrong. You *can't* express it as a schema numeric type because > the document creator must have freedom to specify the number of trailing > zero's, not the schema. Where is this specified? Regards, Ed Day Objective Systems, Inc. ----- Original Message ----- From: "Bob Wyman" <bob@w...> To: "'Rich Salz'" <rsalz@d...> Cc: "'Elliotte Rusty Harold'" <elharo@m...>; "'xml-dev'" <xml-dev@l...> Sent: Wednesday, April 14, 2004 1:03 PM Subject: RE: RE: Schema vs Schema-free (was: RE: XML Binary Characterization WG public list availabl) > Rich Salz wrote: > > Parts of X.fws concern me -- I am thinking of the > > round-trip from XML for something like <error-rate>.500 > > </error-rate> going to a local number, out via > > ASN.1/DER as an IEEE float, and back. Along the way > > it's all too likely to end up as .5, which will > > break my digital signature -- and quite rightly, > > since trailing zero's are semantically significant. > I must admit that I get a little miffed whenever this kind of > objection arises. Certainly, there is a real problem being described, > however, it *isn't* a problem with X.fws or any of the schema-based > alternatives to XML. Rather, the problem is that the schemas are > underspecified. If, as you say, trailing zero's are significant, then > that information should be expressed in the schema. If it was > expressed in the schema, then any schema based alternative should > honor the schema and pass along the tailing (or leading) zeros. > This "problem" that some people attribute to X.fws and similar > systems is really a problem with XML Schema, RelaxNg, etc. The fact > that it becomes more obvious when you have a system like X.fws that > relies on schema's being accurate doesn't change the fact that the > problem exists even without using something like X.fws. For instance, > if I (as a coder) see an XML Schema that tells me something is a > "Float", "Decimal" or "Double", then no one should be surprised if I > read the XML Schema specification and treat the data as defined there. > Thus, for doubles, leading and trailing zeros are prohibited. For > Decimal and Float, leading and tailing zeros are optional but are not > defined to have meaning if present. > Perhaps what is required here is the definition of a new facet > for at least one of these types that would flag the trailing zeros as > signficant. > Of course, an alternative is to simply define the type of a > field to be a string and then constrain it to contain only numeric > values or some number-like pattern. If this is done, then none of the > schema-based processors will do anything other than pass the data > through as it is found in the record. > In summary: The problem here isn't X.fws, ASN.1, etc... -- the > problem, if any, is that the Schema language isn't expressive enough > or that people are using the wrong data types in their schemas. If > X.fws is used with properly defined, expressive schemas, these > problems will not arise. > > bob wyman > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://www.oasis-open.org/mlmanage/index.php> >
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