XOM API for Processing XML with Java

[Michael Abato <mrabato AT earthlink.net>]

I understand, sympathize with, and support not being comfortable with  
not checking. But I'm also not comfortable with not "playing nice" in a  
shared environment. Looking closer at the code, it becomes obvious that  
it is not airtight, as this "fix" will get "unfixed" by any piece of  
code, anywhere, that does a  
System.setProperty("org.apache.xerces.xni.parser.XMLParserConfiguration" 
, ...).

A simple, though still kinda smelly, workaround is to take advantage of  
this flaw and do something like:

>   static {
>     if ( new Builder() != null ) { // force static init
>       System.setProperty(
>               "org.apache.xerces.xni.parser.XMLParserConfiguration",
>               "org.apache.xerces.parsers.XML11Configuration");
>     }
>   }

which resets  org.apache.xerces.xni.parser.XMLParserConfiguration" to  
its original value, which is globally safe.

In addition to not liking the arms race with XOM's implementation  
details, this solution is technically not "thread safe". Should a  
thread in another process attempt to create a Xerces parser between the  
static init of XOM and the resetting of the property, it would throw  
the ClassNotFoundException. This is obviously obscure and limited to  
deploy-time, however.

Michael Abato

On Jun 9, 2004, at 8:25 AM, Elliotte Rusty Harold wrote:

> At 3:25 PM -0400 6/8/04, Michael Abato wrote:
>
> > I would favor looking for system property  
> > "javax.servlet.context.tempdir" (which implies you are in a servlet  
> > container) and respecting a user-set system property like  
> > "nu.xom.no-verify-XML1_0". Other known containers could be added as  
> > "signals" are identified. Does anyone know a good EJB signal?
>
> The problem is XOM needs to do this. Not performing verification is  
> not an option I'm comfortable with. The code assumes the parser has  
> verified XML 1.0 well-formedness, and the only way to make current  
> versions of Xerces do this is to set that system property to point to  
> my own parser configuration. I filed the bug report you referenced to  
> try to let me do this just for XOM's parser without stepping all over  
> everyone else's parsers, but so far I can't see how to do that.
>
> --
>
>   Elliotte Rusty Harold
>   elharo AT metalab.unc.edu
>   Effective XML (Addison-Wesley, 2003)
>   http://www.cafeconleche.org/books/effectivexml
>    
> http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/ 
> cafeaulaitA