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Rick Marshall wrote:
> hierarchies fail,
hmmm... isn't the internet a hierarchy? has that failed?
> and this is my struggle with xml at the moment, when
> they have to support multiple hierarchies simultaneously. and they
> largely fail because of a) the update problem, and b) the new hierarchy
> problem. reverse bill of materials is a case in point.
> having said that xml works really well where neither of these are an
> issue - documents where the "semantics" don't change only the contents;
> and as i said before moving transactions between systems.
> even relational systems have problems because the semantics is embedded
> in the sql select statements. most so called post relational systems
> (not really sure that's a legitimate term, even though it's used a lot)
> basically embed semantics back into the structure.
> things like owl and to a lesser extent name spaces try to express the
> semantics as a meta model. imho a far superior approach. i just don't
> like naming relationships - prefer to acknowledge they exist and what it
> takes to define them, but not necessarily name them.
> now to xml and the cinderella id tag. the same effect as the
> hierarchical xml could be achieved by allowing a name/value pairing to
> store the structure as attributes in the xml tag and they should be
> treated as elements as well.
> the id tag is the required unique key, while special associate elements
> store structure. this has the advantage of flatenning the xml and
> allowing the parsers to create structure on the fly to suit the
> <home id="456"><home_elements/></home>
> <person id="123"><associate
> which would be approximately
> <home id="456">
> <person id="123">
> early days, but something like this would be much better for data
> modelling. perhaps we can have post-xml? ;)