SAX: finalising org.sax.xml.Parser

[David Megginson]

Don Park writes:

 > If I remember correctly, what David is trying to do is provide us with means
 > to parse XML data from a byte stream as well as character stream.  Since
 > Reader will actually hide the byte-based aspect of the data stream, it in
 > inappropriate for our purpose.
 >
 > XML character stream is also very useful when XML data is generated and
 > processed within a framework.  In such a system, converting character
 > streams to byte stream and then converting it back to character stream is
 > unnecessary.

This is true, but I think that James's point is well taken.  The
character _buffer_ doesn't really buy us anything.  I am reluctant to
use a character reader for two reasons:

1) It is a concept that doesn't translate well to languages other than
   Java (or even to Java 1.0.2 for that matter).

2) It imposes another architectural requirement on SAX-conformant
   parsers (the ability to receive characters directly, bypassing the
   normal input mechanisms), and I'm trying to keep interference to a
   minimum.

It is slightly inefficient to go from characters to a byte stream to
characters, but it's not that bad (especially if we use ISO-8859-1 or
UCS-2 for the encoding), and it keeps SAX simple and general.  Given
the discussion so far, then, we are ending up with something like
this:

  package org.xml.sax;
  import java.io.InputStream;

  public interface Parser {

    public abstract void setEntityHandler (EntityHandler handler);
    public abstract void setDocumentHandler (DocumentHandler handler);
    public abstract void setErrorHandler (ErrorHandler handler);

    public abstract void parse (String publicId, String systemId)
      throws java.lang.Exception;
    public abstract void parse (String publicId, String systemId,
                                InputStream inputStream)
      throws java.lang.Exception;

  }

If you need more, you can always extend the interface:

  package com.acme.xml;
  import java.io.Reader;

  public interface SuperParser extends org.xml.sax.Parser {

    public abstract void parse (String publicId, String systemId,
                                Reader reader)
      throws java.lang.Exception;

  }

In an ideal world, we'd also have some kind of ability to ask to
parser to turn validation on or off, but I'm not certain that that's
practical: any thoughts?


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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