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   Re: [xml-dev] Pushing all the buttons

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At 8:33 AM -0400 9/21/03, David Megginson wrote:

>I think that James was talking about going from bytes representing a
>Unicode character encoding, not a binary encoding.  There should be no
>platform dependencies in that case.

I understood that, and my point still holds. There are platform 
dependencies in this case. If the native char and string types are 
built on UTF-8 (Perl, maybe?)  then this is straightforward., 
However, when the native char and string types are based on UTF-16 a 
conversion is necessary. Ditto for UTF-16BE to UTF-16LE and vice 
versa. Or UTF-8/UTF-16 --> UTF-32. Languages and platforms do not 
share the same internal representations of Unicode. No one binary 
format will work for everyone.

This conversion is non-trivial too. In the current version of XOM I 
made deliberate decision after profiling to store internal text node 
data in UTF-8 rather than UTF-16. That saves me a *lot* of memory. 
However, the constant conversion to and from the internal UTF-8 
representation to Java's UTF-16 representation imposes about a 10% 
speed penalty. I chose to optimize for size instead of speed in this 
case, but I wouldn't suggest imposing that cost on everyone by making 
all XML data UTF-8.


   Elliotte Rusty Harold
   Processing XML with Java (Addison-Wesley, 2002)


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