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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Separate the data model from presentation and makethe data
 On 11/22/2015 10:47 AM, Costello, Roger L. wrote: Au contraire: take for example the followingHi Folks, Assertion: Accessing/manipulating element nodes is simpler, easier, and faster than accessing/manipulating text. An element-based data model is better suited to XML's strengths than is a text-based data model. Proof by example: Case 1: Retrieve "west" Text-based data model: <edge>garden west door home</edge> XPath to retrieve "west": substring-before(substring-after(., ' '), ' ') Element-based data model: <edge> <garden/> <west/> <door/> <home/> </edge> XPath to retrieve "west": *[2]/name() Clearly, retrieving "west" in the element-based data model is simpler, easier, and faster. <edge>garden west door home</edge> <edge>garage west door office</edge> Now how will you distinguish <edge> <garden/> <west/> <door/> <home/> </edge> from <edge> <garage/> <west/> <door/> <office/> </edge> ? Clearly you have to have something stored somewhwere that will tell you what "garage" and "office" and "garden" and "home" are, and you will have to somehow know that the two "wests" have the same meaning ... if they do, but they might not. Now each element name has to be stored against the element's node structure - as text (OK yes, could be hashed or otherwise encoded - but in the text node, the content also has to be stored as text (or some encoded version). Now you have many more element structures but the same amount of text. The text of each element name - e.g., the "west" names - must either be duplicated or interned, but the same can be said for the text content itself. How is that supposed to be more "efficient"? And why should it be any easier to process? It all depends on what use you plan to of the data, and what the meaning is supposed to be. "West garden door" might be an atomic label, in which case you probably want it to be stored verbatim, not dissassembled. Before holding forth about processing efficiencies, and which XPATH expression might be "faster", it would be wise to ask the people who actually know how the processing is done, such as XSLT designers. Otherwise you are merely engaging in the equivalent of premature optimization. Anyway, XML's strengths are for data interchange, not necessarily "processing". If you want to emphasize small, fast data transfer, you could always use e.g., one of the ASN.1 binary encodings. If you want to emphasize querying, you could always import into a database. But I should stop here, since the original message sounds too much like a troll. TomP Case 2: Retrieve a range of data items (2nd to 3rd data items) Text-based data model: <edge>garden west door home</edge> XPath to retrieve the desired range of data items: tokenize(., ' ')[position() = (2,3)] Element-based data model: <edge> <garden/> <west/> <door/> <home/> </edge> XPath to retrieve the desired range of data items: *[position() = (2,3)]/name() Clearly, retrieving a range of data items in the element-based data model is simpler, easier, and faster. Of course, at the point of presentation we will want to convert the element-based data model to a text-based data model. Recommendation: Separate the data model from presentation details and make data models element-based. Let's take a dramatic example. Rather than this: <living-room> you are in the living room. a wizard is snoring loudly on the couch. </living-room> use this as your data model: <living-room> <you/><are/><in/><the/><living-room./> <a/><wizard/><is/><snoring/><loudly/><on/><the/><couch./> </living-room> and use the former only for presentation. Do you agree? /Roger _______________________________________________________________________ XML-DEV is a publicly archived, unmoderated list hosted by OASIS to support XML implementation and development. To minimize spam in the archives, you must subscribe before posting. [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ Or unsubscribe: xml-dev-unsubscribe@lists.xml.org subscribe: xml-dev-subscribe@lists.xml.org List archive: http://lists.xml.org/archives/xml-dev/ List Guidelines: http://www.oasis-open.org/maillists/guidelines.php 
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