Xalan requires XML parsers to support DeclHandler?

[Don Park <do...@docuverse.com>]

Hello, my first post here.

Here are some observations I made which eventually results in Xalan
requiring XML parsers to support DeclHandler:

1. SourceTreeHandler class implements DeclHandler.

2. SourceTreeHandler is used by TransformerImpl class as input content
handler.

3. TransformerImpl.transform() method installs input content handler into
source XML reader as DeclHandler using XMLReader.setProperty() method
without catching SAXNotSupportedException.

Given that DeclHandler is an optional SAX2-ext interface and not supported
by all the XML parsers, Xalan will fail under these XML parsers even when
DeclHandler is not necessary.  Resin, for example, has an interal XML parser
which does not support DeclHandler and will fail to transform using Xalan
when source document is embedded within JSP (i.e. Jakarta's xtags taglib).

Suggested fix is to catch ignorable SAXNotSupportedExceptions.

Best,

Don Park
Docuverse