"Andy Carlson" <[EMAIL PROTECTED]> wrote: > Hi all, > > I've just spent quite a while tracking down a weird problem... > > I'm running a servlet under Tomcat 4.0. The servlet includes Axis, which > in this case is using the Xerces (1.4.3) parser. Everything works fine - > no problem so far... > > Now I try to run the same servlet on Tomcat 4.0 embedded in JBoss (2.4.1) > and I get the following:- > > java.lang.ClassCastException: > org.apache.crimson.jaxp.DocumentBuilderFactoryImpl > at > javax.xml.parsers.DocumentBuilderFactory.newInstance > (DocumentBuilderFactory.java:152)
this is quite a well known problem. it boils down to classloaders. standalone tomcat 4.0 works because it has classloaders specially rewritten to work with JAXP. jboss uses a different system of classloaders and requires special configuration to make JAXP work. the bad news is that some ejb containers are even worse than jboss... <snip> > So what's the answer? > > - at the moment the answer seems to be to avoid mixing Crimson and Xerces > in the same context unless you have a very good understanding of how they > are going to interact with each other - you might get away with it or you > might (like me) spend a long time chasing strange problems. > > ... but this is bad news because it means that if my servlet uses an XML > parser, I have to check whether the app server I'm deploying on is using > another one in a way which is going to cause a conflict. > > - For the future it would seem to be a better approach to agree on a > single implementation of JAXP within Apache, put it in its own JAR and > explicitly disallow (in the JAXP spec?) XML parser implementations from > reimplementing all or part of JAXP in their own JARs. this isn't an apache problem - it's a JAXP problem. even with only one apache implementation you'd still get version conflicts :( if you want deployment independence i'd say you've got two choices: 1. throw away JAXP and directly use the parser of your choice. parser independence is vital for components but isn't really necessary if you're writing a web application. 2. don't deploy any parser libraries with your application and insist that JAXP is correctly set up on the deployment system before you deploy. - robert --------------------------------------------------------------------- In case of troubles, e-mail: [EMAIL PROTECTED] To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
