XOM API for Processing XML with Java

[Elliotte Harold <elharo AT metalab.unc.edu>]

There are two major issues on my list for XOM 1.1: XPath and internal 
DTD subsets. They're a lot of other targets of opportunity, but these 
are the two that I think are causing real pain by their absence. First 
off: internal DTD subsets.

The API for this is simple:

public void setInternalDTDSubset(String subset)

No muss. No fuss. The tricky part is implementation. I don't want to 
write an entire DTD parser, and I'd like to avoid bundling yet another 
3rd part library. I had thought I could implement this simply by using 
Builder, but someone (Wolfgang?) pointed out that this failed because 
Builder always resolves external entity references. But we can work 
around that. Rather than using a Builder, I'll just use a SAX parser 
directly, and turn off external entity resolution.

There are still some issues of concern, though:

1. The document might not be able to be read in again, if the entities 
the internal DTD subset references are not found. I think we can live 
with this, though it does bother me.

2. The internal DTD subset might declare default attribute values and 
types which conflict with the attributes currently present or not 
present on particular elements. This breaks round-tripping. However, at 
least with respect to attribute type, round-tripping is imperfect already.

The alternative would be a much more complex API that has separate 
methods like addAttributeDeclaration, addElementDeclaration, 
addEntityDeclaration, etc. It would be more modular, and that might be 
of use to somebody. I could probably do a syntax check of each target 
individually, and perhaps apply default attribute values and adjust 
types in the document as attribute declarations were added. But then 
what happens when a document type declaration is detached? Honestly, 
this is just too complex and I can't see it happening. I think the worse 
is better, 80/20 solution is just to accept the internal DTD subset as a 
string and ignore the round tripping issues.


Thoughts?


--
Elliotte Rusty Harold  elharo AT metalab.unc.edu
XML in a Nutshell 3rd Edition Just Published!
http://www.cafeconleche.org/books/xian3/
http://www.amazon.com/exec/obidos/ISBN=0596007647/cafeaulaitA/ref=nosim