RE: Problem with XMLReader

Thanks for the suggestions.
Let me give you a more concrete (but still hypothetical) example.

A WebEngine needs to be configured with a SAX source. It could
be a file, db, etc. So a property of the SAX source is where it
gets its SAX data from. I could configure both an InputSource and
an XMLReader but it does feel very messy. And it still leaves me
implementing XMLReader which is not Simple.

So I'm still needing a class that says "Get your SAX here", and
allows its users to decide when.

I guess the problem is not that I don't have a way to do it. I
think my ContentHandlerSource or any of Paul's solutions work.
The issue is just that this seams to me to be a common SAX problem
and SAX does not provide an answer.
I'm suggesting it should.

Joe.


Paul Brown wrote:
> > From: [email protected] [mailto:[email protected]]
> > public interface ContentHandlerSource
> > {
> >     /**
> >      * Call this method to get an XML document streamed
> >      * passed ContentHandler
> >      */
> >     void writeToContentHandler(ContentHandler h) throws SAXEx...;
> > }
> > The logic behind it - sources of SAX events sometimes need to 
> > be configured at run-time. Writing an XMLReader for each is time 
> > consuming, and hard because InputSources aren't a good fit 
> > to many data sources (in-memory, DBs, etc).
> 
> Suggestions:
> 
> 1) InputSource isn't final and XMLReader is an interface, so 
> you can make your own versions that may be incompatible with 
> other objects.  For example, if you have an XMLReader 
> implementation that turns a JDBC rowset into a stream of SAX 
> events, then you are free to subclass InputSource to get a 
> JDBCRowsetInputSource that has get/setStatement() and 
> get/setConnection() methods, etc., and then have an XMLReader 
> implementation that does:
> 
> 	public void parse(InputSource is) throws SAXException {
> 	  if (!(is instanceof JDBCRowsetInputSource)) {
> 	    throw new SAXException(is.getClass().getName() + " is not "
> 	      "a subclass of JDBCRowsetInputSource");
> 	  }
> 	  /* DO STUFF HERE */
> 	}
> 
> This particular suggestion is intended to provide a 
> reasonable level of compatibility with other SAX consumers.  
> For instance, if you're using a TrAX-compliant XSLT 
> processor, when it receives a SAXSource (XMLReader / 
> InputSource pair), it does (or should do):
> 
> 	ss.getXMLReader().parse(ss.getInputSource());
> 
> to generate events.  It's up to you to be sure that the 
> InputSource subclass and XMLReader implementation are compatible.
> 
> 2) You can create your own abstract class that has a 
> pullFromSAX(XMLReader xr, InputSource is) method that 
> attaches a ContentHandler, etc., and then calls parse on the 
> supplied InputSource.
> 
> 3) You can create a utility class with a static method that 
> accepts a ContentHandler (and DeclHandler, etc., too?), 
> XMLReader, and InputSource tuple and then performs the 
> relevant operations.  In this case, your 
> writeToContentHandler() would be equivalent to 
> UtilityClass.consume(this,myXR,myIS);
> 
> Just some pre-coffee suggestions.
> 
> 	-- Paul
> 
> 
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