Hello Duffiana,
XML parsers can be the bane of our existence at times ...
The most important principles I have applied to be able to use Digester
separate from Struts include:
- Digester (in Struts 1.0) requires a JAXP/1.0 or later parser. I've
used it successfully with JAXP/1.0.1 and JAXP/1.1 (the latter is
recommended) and Xerces 1.3.1.
- Make sure you have one and only one parser in your classpath. If you
have both JAXP and Xerces, for example, there will be two occurrences
of classes like org.xml.sax.HandlerBase -- and you will definitely have
problems if you load the HandlerBase class from JAXP while you are
using Xerces (or vice versa).
- While checking your classpath, also look in $JAVA_HOME/jre/lib/ext
and make sure that there are no parser JAR files there either.
Craig McClanahan
On Tue, 3 Jul 2001, Duffiana Jones wrote:
> Hi,
>
> I'm facing troubles while attempting to execute classes using Digester
> objects outside the struts framework : the error is
> "java.lang.LinkageError: Class org/xml/sax/HandlerBase violates loader
> constraints", and occurs when I attempt something like
> "digester.parse(uri);"
>
> I've tried all following configurations :
>
> * For all configurations
> - Linux RH7.0 (+patch for the glibc)
> -Tomcat (when used) 3.2
> -Junit: 3.7
> -Struts: 1.0
>
>
> * Configurations 1
> - jaxp1.0.1 / jaxp1.1
> - xerces 1.2.3 / 1.3.0 / 1.4.1
>
> * Configurations 2
> - jaxp1.0.1 / jaxp1.1
> - parser.jar (with jaxp1.0.1 distrib) or crimson.jar (with jaxp1.1
> distrib)
>
> * Configuration 3
> the one that confuses me the most : I can run the Struts example
> application using the libraries from the tomcat lib directory ... but I
> can't run my application using the exact tomcat classpath (+ my own
> classes)
>
> * Configuration 4
> I even recompiled the struts framework and then tried to run my app
> using the exact same libs that were used at compile time (IMHO that
> shoud have removed any LinkageError, as far as I understand this
> message), and always get the same error.
>
> * notice : I've tried with both final SUN releases of jdk1.2 and jdk1.3
>
> Given this, questions are :
> - may the code itself (miscreated Digester object or other reasons I
> can't figure out) causes the LinkageError, or can I be sure that's a
> libraries related problem ?
> - has anyone already used Digester objects outside the struts framework
> (my need for doing this is to allow unit test with JUnit test runner,
> but I can see many other reasons that may lead one to use the Digester
> facilities outside struts), and if so, with which parsers and JAXP API
> releases ?
>
> I've checked the struts archives at covalent.net and
> www.mail-archive.com (the pointers given at the jakarta resource page),
> but didn't find anything related to this.
>
> BTW I've seen in this list lot of posts about libs release number
> troubles : for jaxp, xerces, and xalan, and even for ant for them who
> want to compile the stuff themselves. IMHO, a summary about the faced
> issues and the consistently working releases set would be of great
> usage, and may even delete unusefull noise (as the one I'm making) from
> the list. The struts documentation, is very nice about features and
> architecture, appears somewhat vague about the prerequisites.
>
> thanx for any idea.
>
> duf.
>
