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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Pushing all the buttons
 At 8:15 AM +0700 9/21/03, James Clark wrote: >With Sun's Fast Web Services stuff, they are going directly from a >sequence of bytes to application-specific objects, cutting out at >least two of the layers in the XML-based implementation. I am quite >willing to believe they can get an order of magnitude improvement. The problem with this approach is that it's very platform specific, as binary approaches have always been. I suspect Sun's approach will work well for Java. But will it work well for C? What's the performance impact when byte orders need to be flipped when deserializing? I doubt very much Sun can get an order of magnitude improvement on all platforms of interest, much less with all documents of interest. In fact, I wouldn't be surprised if their data optimizations for Java actually decrease performance for programs written in Perl, C, or other languages. >To make this practical a little XML subsetting is required. First, >I think you would need to do what the SOAP folks have done and >disallow DTDs; handling entities would make this approach very >difficult. Second, you really need to fix on a single encoding. I >think UTF-8 is the obvious choice for Web services. A single >encoding allows you to cut out a whole layer of your processing >stack. Instead of converting bytes to characters and then parsing >those characters into objects, you can parse the bytes directly into >objects. That runs into the same problem. This works very well when your internal representation is UTF-8. However, when the internal representation is UTF-16 as it is in Java or something else then extra work is involved. You can't just slam binary data from a stream into a memory location and expect it to be an object or data structure appropriate for the local environment. You can make this work for one preferred environment, yes, but you can't do it for all the languages and platforms people use. I very much suspect Sun's proposal would have the "accidental" effect of strongly encouraging developers to use Java. Of course, it will work if you use C# or Perl, but it will work better with Java. We've seen this before. It's not an accident that Java's native floating point support fits Sparc chips much better than X86 chips. Binary formats are always tied more to some platforms than others. Binary is not as interoperable as text. -- Elliotte Rusty Harold elharo@m... Processing XML with Java (Addison-Wesley, 2002) http://www.cafeconleche.org/books/xmljava http://www.amazon.com/exec/obidos/ISBN%3D0201771861/cafeaulaitA 
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