XOM API for Processing XML with Java

[Michael Kay <mike AT saxonica.com>]

Interesting.

I imagine it was done for space saving, though that's largely redundant with 
the changes to the String implementation in Java 9.

I'm interested because we're moving to use of byte arrays (one, two, or three 
bytes per character) in the Saxon tree implementation, but that's to achieve 
unicode codepoint addressing for XPath operations like substring(), where 
UTF-8 doesn't help at all.

Michael Kay
Saxonica

> On 20 Jan 2021, at 09:01, Michael Whapples <software AT mdw.onl> wrote:
> 
> Hello,
> 
> I was recently profiling an application which uses XOM with the intention 
> to improve performance. I noticed that in a section of code where it does a 
> reasonable amount of XML manipulation a significant amount was down to 
> calls to Text.setValue and Text.getValue. I could appreciate setValue may 
> need to do some validation checks, but I had always thought getValue would 
> have been a simple getter, the profiling data told me otherwise.
> 
> 
> I decided to examine the XOM source code to see exactlyt what is being done 
> in the Text class. This leads to the following question:
> 
> Why is data stored as a UTF8 byte array rather than as a String? Storing as 
> byte array requires conversion and associated memory allocation upon every 
> call to setValue and getValue. I see nothing in the source code where the 
> byte array is used directly. The only functionality I can see related to it 
> is that if the JVM does not support UTF8 encoding then setValue will throw 
> an exception, but I would have thought this check would have been better 
> placed in some initialising code so it is only run once per JVM session.
> 
> 
> Could this be changed in XOM or is there some reason I have overlooked why 
> it is done the way it is?
> 
> 
> Regards
> 
> 
> Michael Whapples
> 
> _______________________________________________
> XOM-interest mailing list
> XOM-interest AT lists.ibiblio.org
> https://lists.ibiblio.org/mailman/listinfo/xom-interest