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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Re: Where does the "nothing left but toolkits" myth come f
 On Thu, 10 Feb 2005 07:27:33 +1100, Rick Marshall <rjm@z...> wrote: > > even though i have heard of some excellent use cases for "binary xml" > i'm still not sure that technology won't fix that. That's probably true in the long run. In the short-to-middle term, there are very serious technological constraints on bandwidth and batteries (which are drained all the more quickly by additional CPU usage) on mobile devices. [1] For the "XML is too slow to parse" use cases, I agree that technological fixes -- dear old Moore's Law, or specialized hardware of the sort Tarari, Datapower, Sarvega, etc. makes -- may well make this problem irrelevant. Of course, the market will determine whether customers want faster XML hardware or smaller/easier XML-ish data. I'll guess that XML text will win (outside the wireless domain, anyway) when interop is a consideration, but developers of multi-component XML software systems (e.g. a DBMS with a client side library, or a "service bus" where different web services are offered in a pipelined manner) will be taking "binary XML" *very* seriously as a way of communicating between their internal components. > so bloatedness does matter, but is xml bloated? no. does it have > redundant information? yes, because it can be compressed. now much? The usual response from binary XML advocates is "at what cost". If you are trying to minimize actual latency to the user, compression seldom actually helps. Also, popular compression schemes don't work until they have a few K bytes of data. For relatively small messages over a slow channel, conventional compression does not hit the sweet spot. Also,if you decompress at the cost of draining the battery in a few minutes, you will probably have dissatisfied customers. Of course, these are all ultimately business decisions about engineering tradeoffs, not hard and fast rules. > > so here's a real problem - will things like xslt have to cope with both > formats? No, XSLT, XQuery, DOM, all work off an XML data model, not the raw syntax. At worst, only the code that builds and serializes the internal data structures must adapt to a binary format that has the same information as XML text. In some prototypes, the binary XML format is analogous to a stream of serialized events produced by an XML 1.x parser. A simpler and more efficient parser can take this format and generate the same events that the original XML text would have. The same event handlers that were written for text input can be re-used for the binary input ... since they have never had any idea of what series of bytes triggered the event. [1] Of course some magic technology breakthrough could come along and change the constraints such that plain ol' XML text is good enough for domains such as wireless. FWIW one of the keynoters (David Yach of RIM) at the VLDB conference last year spent a good bit of time explaining why that is unlikely, and DB people will just have to come to grips with the reality that handhelds play by different rules that the client apps we are used to. http://www.vldb04.org/VLDBKeynoteDavidYach.pdf 
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