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Thanks Tim! This is *really* good, I think I just changed my perspective on things. I had been wondering if I had missed something... On Sun, 19 Dec 1999, Tim Bray wrote: > Both logfiles and continuous broadcasts work just fine, simply send > a series of small XML documents rather than try to pretend the whole > logfile is one parsable object. Yes, using "^L" as the document seperator. > Which is arguably better design anyhow; to start with, among other > things you can validate each record; in principle you can't validate > a doc until you've read it all. Well, if you consider "is-valid()" to be a property of the XML source as it is encountered, then is-valid() is itself not a value, but a sequence of values. The last value having particular relevance in the "document" domain. > I've always thought the single-root-element idea was a good one for > networked apps simply because it allows you to know unambiguously when > you're done receiving useful data, and don't have to rely the programmer > at the other end closing the socket, and the connection teardown time, > and so on. Yes. Ok. This one clicks. Assume a broadcast, let's say from a programmable controller watching 4 gauges and reporting their differentials. The broadcast has a definite beginning. I always thought of it as "infinite" beacuse in practice, the controller can be left on for years... However, there may be cases where the controller needs to be shut down for maintanence... thus, switching the power switch to "OFF", would first send the end tag, and then power down. Ok. I can grok this one. Thanks tons! Perhaps the log file might be similar? Let's say I startup a-daemon-with-xml-logging. It would start by creating a new log file by picking the date/time of the run, and then write out the <log> element. As events occur, they are appended as <event/> elements to the file. If the daemon is shutdown gracefully (99.9% of the time), then it can end the log file with a </log> tag. Nice. So, there are only two cases where a log file would not have an end-tag: (a) if the file is read while the deamon is running, or (b) if the daemon crashes. In both of these cases above, SAX can be used to report on the stream as it arrives anyway... This leads me to a question: How do SAX implemetations (like XT) treat files that are opened for writing by another process. Is it possible for them to have behavior like "tail -f" ? > But the real reason XML was done that way was becasuse it was one of > the things inherited from SGML that nobody ever asked to have changed. > Really, I don't recall a single word on that subject at the time. -Tim This is cool. Thank you for humoring my question! ;) Clark 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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