Re: XML Search Engine Holy War - Attributes vs. Elements
DuCharme, Robert wrote: > > >1. Ignore Attributes all together and index Elements and Character Data > >only. > > >The feeling is that the use of attributes should be restricted (by > >authors) and used to allow other scripts/applications to either include > >or preclude the element and resultant children nodes from some sort of > >processing, displaying or further manipulation. > > This shouldn't even be considered. Yes, although a schema designer is free to document a semantic, this is application level design. "All politics is local." A search engine built on that premise is restricting its application space. > Attributes are used for far more than > what the above paragraph describes. Typical uses include many classic search > criteria such as meta-information about authorship, revision stages, and > revision dates. Include security markings in that too. While one might not be smart to use that in a web application, security markings in attributes have been used in SGML DTDs. Redacting... > The sole purpose of ID type attributes is to uniquely > identify elements, and unique identifiers ought to be pretty handy when > searching for information. A system that can quickly locate elements with a > particular value in an IDREF type attribute would be very useful in link > maintenance and implementation. And as in X3D, (being discussed(ID/IDREFS vs NMTOKENS)), for DEF/USE relationships. There are also examples of putting what others might consider "content" into attributes to preserve a symmetry with nodes and fields. Some use and will use XML just as a binding to an abstract description (eg, X3D). There is no simple case or practice that enables an engine to ignore attribute values and types unless one is blinding the engine by design. > but a nice > thing about implementing storage of attributes is that they map more easily > to relational databases where ID and IDREF attributes can be easily indexed > for searching. Yes. There are scripts and samples that do that now. What I see in practice is that export and import systems start out using only elements mapping field names to GIs, then after some experimentation, they begin to rely more on GIs and attributes. Applying ID/IDREF depends on how you use the names. It is good for primary key/foreign key relationships if strict relational rules are followed, but when packing/serializing, it isn't necessarily strict so NMTOKENs may be preferred. The question is one of requiring a validity pass from the XML processor. len 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 unsubscribe, mailto:majordomo@i... the following message; unsubscribe 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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