I'm not sure there is a portable way to do this. Given a specific JAXP
implementation (such as Saxon or Xalan) you can do it by making your
URIResolver be a subclass of the standard URIResolver, and invoking the
super.resolve() method. You could make it a bit more portable by having your
URIResolver accept a reference to the standard URIResolver using a
setStandardURIResolver() method when it is first instantiated.

Michael Kay 

> -----Original Message-----
> From: Bjvrn Boxstart [mailto:Boxstart@xxxxxxxx] 
> Sent: 05 April 2004 12:40
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Using a custom URIResolver
> 
> Hello all,
> 
> I'm using a custom URIResolver in a transformation. This is 
> because I'm using the document function to find related 
> documents for the document that is currently being 
> transformed. What I want is that only when the referenced 
> file is not being found by the default URIResover, that my 
> custom URI Resolver takes over and finds a template to be 
> used for that single transformation.
> 
> The problem that I have is that I first want the default URI 
> Resolver to act and only when it's result is null or an 
> exception, that my custom URI resolver takes over. Until now 
> I can only find how to use the default URI resolver (in case 
> my own URI resolver cannot resolve the reference) by using 
> null as the return value of the resolve() method.
> 
> Is there anybody who knows how to solve this problem or else 
> what the code is for the default implementation of the 
> default URI resolver so that I can modify it to let it act as 
> I want it to?
> 
> Thanks in advance!
> 
> Best regards,
> 
> Bjvrn Boxstart