On Sat, 8 Jan 2005 13:48:47 -0800, Roy T. Fielding <[EMAIL PROTECTED]> wrote: > On Jan 8, 2005, at 2:21 AM, Danny Ayers wrote: > > Perhaps I wasn't clear enough. XML has containment. Individual > > specifications may assign it semantics. RDF/XML assigns it semantics > > corresponding to the RDF model. Without either the individual > > specification's definition, or a generalised interpretation like > > RDF/XML's all you have is syntax featuring containment. > > No, you were clear, it was just that your statement is false. > Element containment is a semantic that almost all XML data formats obey. > In fact, the only one I know of that doesn't is RDF/XML. No other > format needs to assign those semantics to XML. > > > But XML containment can only express tree structures. To express graph > > structures, the containment must somehow be violated. RDF is a graph. > > And Atom feed is a tree. If we try to express tree structures with a > graph language, we create complexity that would not exist with a tree > language because a tree already has constraints built-in. The extra > constraints that RDF needs in order to dig itself out of its own hole > are not necessary for languages that avoid the hole in the first place. > > >> I do hope that folks understand that the relationship should be > >> obvious to anyone who does not > >> work in a language that is as perversely non-mark-up as RDF/XML. > > > > Well there you have it - it is possible to design XML languages that > > are perverse. So we can't rely on everyone following the 'obvious' > > relationship pattern. Making it explicit should help prevent > > misinterpretation. > > On the contrary, we can safely ignore languages that are perverse > in their use of XML because those languages will have to define > their own islands of semantics which are self-contained and > irrelevant to their surroundings. Other languages do not have > to understand the non-containment semantics of rdf:Description > because those semantics are defined by RDF/XML regardless of > what other language it may be embedded within.
Earlier you said: [[ While I don't see any reason not to make XML's mark-up relations explicit in the specification, I do hope that folks understand that the relationship should be obvious to anyone who does not work in a language that is as perversely non-mark-up as RDF/XML. ]] While I disagree with some of the other points you have made (probably none of the facts, more the general focus), I believe the first part of this sentence is the issue that most directly affects Atom, and on that I agree. Cheers, Danny. -- http://dannyayers.com
