[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Streams, protocols, documents and fragments
I agree with the arguments so far - just send lots of little documents, and the protocol is just a layer on top, to be removed by the input stream processor. But, isn't the example below not wf XML - it doesn't seem to have a prolog? I have no problem with that either - again, you need a client side stream processor to pick apart the XML ... what do I call them? FSA 'chunks' ... chunks and, using some client side determination, add the prolog - and then pass it to the XML parser as a WF (and hopefully valid) XML document. This is 'trivial', and interleaving the protocol stuff is no great problem (plenty of examples, and I've done it at least 5 times for different socket-based systems). My concern tho' is that we require a piece of Client-side stream processing logic to pick up the XML 'chunks' and convert them to Valid WF XML - and this is not standard (read 'generally agreed' to avoid mention of inertia). Fun tho' tim ______________________________ Reply Separator _________________________________ Subject: RE: Streams, protocols, documents and fragments Author: Mark.Birbeck (Mark.Birbeck@i...) at unix,mime Date: 24/02/99 15:18 > From: Borden, Jonathan [SMTP:jborden@m...] > My sole purpose in discussing 'document > fragments' was because the thread had gotten stuck on the notion that > a > continuous XML stream would contain a single long document (perhaps > w/o a > closing tag) and the actual PDU's consist of document fragments ... > the > point is that if we create a protocol on a stream which transmitts > multiple > documents, there is no loss of functionality over a solution employing > 'document fragments' > I agree with this. And the point I was trying to get to was that therefore we don't need to introduce loads of terms on top of XML 1.0 to understand the concepts. I still think all of this is being over-complicated - but then maybe I'm the one who's missing something, so let's see. I don't follow why so many suggestions to resolving this problem involve stepping 'outside of' XML 1.0. We have suggestions for sync characters like ^C and ^L, we have the proposal that XML 1.0 should be fundamentally altered to allow the concept of a 'not well-formed' document (or one that may *become* well-formed at some point in the future), we have proposals for documents that contain subsets of validity. All of these suggestions seem to go against the grain of what XML is about. XML 1.0 already copes with streams and files. A physical XML document is a linear sequence of characters conforming to certain rules. You can't tell whether those rules have been met until you have received the entire sequence of characters. You know when you've reached the end by the closing tag. That's it! There's not much else you can do about it, because that's what XML is all about - well-formed, possibly validated documents conforming to certain rules. Now, the fact that the beginning and end of this sequence of characters may be presented to the parser eight hours apart is to me an application problem. If someone has a document that takes eight hours to arrive then maybe they should re-think how they're setting the system up. If it's a massive document that can only be processed in its entirety, and if any part fails to arrive the whole document fails, then sure, you have to go ahead and send it over eight hours. But the stock ticker example is not like this. If I miss the stock price for Microsoft at 11am, then I can still make use of the stock price for Microsoft at 11.20am. It will affect my historical archives, but at least I have something to display. It is not an 'all or nothing' situation. So, accepting for a moment that we should transmit many documents throughout the day, rather than one big one, it leaves the question of demarcation. And here I'm surprised that people want to step outside of XML to find a solution. Say we send the following: ^L <stockPrice timestamp="19992402141500"> <ticker>MSFT</ticker> <price>1000</price> </stockPrice> ^L <stockPrice timestamp="19992402132540"> <ticker>ICI</ticker> <price>1010</price> </stockPrice> ^L < Protocol stuff snipped > 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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