SAX: String Internalisation and a CORBA/DCOM Question

David Megginson ak117 at freenet.carleton.ca
Sat Apr 18 21:36:20 BST 1998


Here's another last-minute SAX question: should org.xml.sax.Parser
expose a method for internalising strings?

  public abstract String intern (String s);

Most Java-based parsers, at least, already use some type of
internalisation (but not, usually, the inefficient
java.lang.String.intern() method) for names -- the SAX driver could
expose this functionality if support is already there, or do its own
internalising if support is absent.

As someone has already pointed out, internalised strings will make a
dramatic difference for the speed of applications, since applications
can use a simple '==' operator (or the local equivalent) to test for
equality rather than a slow subroutine like java.lang.String.equals().

My only concern has to do with distributed environments: is it
possible to use internalisation with CORBA or DCOM?  In other words,
is there a way to guarantee that an object broker returns what turns
out to be the same object/pointer during different calls?  Help or
advice will be gratefully accepted.

By the way, here's the minimum list of what should be internalised in
the callbacks from the SAX parser:

- element type names in DocumentHandler.startElement and
  DocumentHandler.endElement 

- attribute names in AttributeList.getName()

- attribute types in AttibuteList.getType() (both variants)

There are other candidates, such as tokenised attribute values, PI
targets, and notations and entity names.  How large should the list
be?


Thanks, and all the best,


David

-- 
David Megginson                 ak117 at freenet.carleton.ca
Microstar Software Ltd.         dmeggins at microstar.com
      http://home.sprynet.com/sprynet/dmeggins/

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