I'm not a great fan of picking things up by virtue of the fact that you find them lying around on the classpath. That leads to a lot of the problems one sees with the JAXP factory mechanism. It's expensive to search a large classpath, and the results aren't always easily predictable, because many environments create the classpath for themselves without giving you much control. Saxon works this way with "known" external object models such as JDOM and DOM4J - if the support module can be loaded, then it is used; but for "unknown" user-defined models, you have to register it with the Configuration.
I think what you are looking for is a kind of "meta-URI-resolver", which is registered to Saxon as "the" URIResolver, but which actually delegates the work to subsidiary resolvers based say on the URI scheme. That shouldn't need any Saxon changes.
Michael Kay

From: alan.painter@hsbc.fr [mailto:alan.painter@hsbc.fr]
Sent: 21 January 2009 14:10
To: saxon-help@lists.sourceforge.net
Subject: [saxon] RE saxon-help Digest, Vol 32, Issue 14

Hi Michael et al,

I've been using Saxon(ica) quite a bit with different URI resolvers in order to read/write documents from some specialized in-house datastores.  Works great and has inspired enthusiasm.

I'm now looking for a way of "injecting" URIResolvers into a given framework without having to rewrite the user URIResolver.  

To try to motivate this a bit ...

Say you have a working system with an embedded Saxonica, and you want to add a new URIResolver for a new protocol, it'd be nice to be able to just put the new Resolver jar on the classpath and have Saxonica recognize it for you.  Some external properties might be necessary in order to match up resolvers with protocols.

To give a concrete example, say that you want to add a new resolver/protocol to Kernow, without rewriting parts of Kernow (and/or Saxonica).

Any ideas/comments on this?

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