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blog名称:语义Web step-up
日志总数:22
评论数量:81
留言数量:5
访问次数:214974
建立时间:2004年10月29日 |
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 [语义Web理论]针对XMLer的语义Web介绍
读书笔记, 科学研究
orangebench 发表于 2004/11/14 16:04:51 |
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A No-nonsense Guide to Semantic Web Specs for XML People [Part II]
part 1：http://www.betaversion.org/~stefano/linotype/news/57/
提到了XML和RDF的区别：Now let us confront this with the above RDF model:
1。the XML model needs a root element and since this looks like an addressbook, the person doing the schema decided to use such an element for inclusion. It could have been anything really, but the point here is that if we take those elements and move them in another context, we need to rewrite the XQuery or the XPaths that lead to them, unless, of course, we started our XPaths with //.2。the XML model is able to identify a particular element inside the document space, but that ID is not guaranteed to be unique across documents (the impact of this could be reduced if the practice of using URIs for ids was more widespread but it’s really not the case, also because very few XML people care about absolute identification of elements, considering XPaths a much more flexible way to address parts of a document).3。the XML model does not, on its own, have a native distinction between URIs and Literals. This means that “Bob” and “mailto:bob@work2.example” are treated equivalently by the XML parser, unlike in RDF.4。last, but not least, the XML model does not make the relationships between elements explicit and uniquely addressable.
最后，XML中元素嵌套的Implicit semantics导致无法自动把XML转成RDF。
if this implicit semantic information is somehow made available, it is entirely possible to transform XML into RDF, for example, thru the use of an XSLT stylesheet. As I showed above, this stylesheet cannot be a general one-size-fits-all one, but must be tuned for the specific schema and/or for the specific requirements that the data consumer might have (for example, what data should be given a literal and what should be given a URI). Here is a paper that part of our group wrote to describe what we have done in the migration of XML data into RDF.
So, in short: should you care about RDF? For now, you are safe if you care about keeping your own data valid and coherent. The semantic web is trying hard to unlock the chicken-egg problem of “no killer app until data, no data until killer app” and automatic trasnformation of existing data into RDF is what I think is going to unlock it. Also, the fact that we are building tools that you can now use to operate on your RDF data, for example to browse and search it, will show you what you can gain by making those relationships explicit. |
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