[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Documents and Document Fragments
Mark Birbeck wrote: > It's also relevant to document fragments. In previous posts, I was > trying to say that as far as a parser is concerned, whether it receives > a complete XML document by retrieving a file from a disk, a page from a > web server, or four nodes from an object database is neither here nor > there. As far as it is concerned, it has an 'XML document'. I called > this a 'logical' document because I wanted to indicate that it may not > actually exist in any physical form, but it is a > 'data-object-that-conforms' item, and that if we can process an 'XML > document' we can process one node, many nodes or the whole tree. You > don't then need to devise another system to process well-formed > 'uberdocuments', and yet another to process well-formed 'document > fragments' or 'microdocuments' or whatever. Although it may reflect the state of existing parsers, I disagree with this assessment of how XML parsers must relate to 'XML documents' and 'document fragments'. It seems like it has things backwards. You imply that if a parser is able to process a collection of nodes in one particular form, that it is able to process a collection of nodes in any arrangement whatsoever. Perhaps, but not necessarily. An XML document has to have a root node. A subset of that document, produced by an XSL engine or by some other means, doesn't necessarily have a root node. An XML parser may or may not require that a document has a root node. Any parser capable of handling documents without a root will do fine if one exists, but the reverse it not necessarily true. Perhaps the question is whether there is a difference between an 'XML parser' and an 'XML document parser'. Which brings up the question of whether there is such as thing as XML (by definition well-formed) that is not a XML document. I think there is, and that this is where the term 'document fragment' is useful. Here's a simplified version of how I'd like the world to be defined: :) document fragment: A piece of well-formed XML, that may or may not have a root element. In the parlance of the spec, it would probably be called a 'well-formed textual object'. Doesn't even have to contain any elements. Colloquially synonymous with 'XML'. XML document: A document fragment that, in the words of the spec, 'when taken as a whole matches production labeled document'. In practice, some XML with a single root element. Parsed entities must also be well formed. XML parser: Something that accepts XML as input and/or treats its input as XML. May or may not care if the input is well-formed and/or valid. It's quite possible that cat(1) would qualify as an XML parser by this definition. XML document parser: An XML parser that expects an XML document as input, and complains if it does not receive one. A 'conforming XML processor' in the spec's terms. (Although the spec often uses just 'XML processor' and implies 'conforming'). Which is to say, that I think the notion of 'document fragment' is still useful, and that it is worthwhile to think about textual XML that is not in the form of an XML document. nathan kurz nate@v... xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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