Incidentally, in reading the Tomcat docs for "Classloading", it seems that any classes in a web app's "lib" directory *should* be able to see classes in the "shared/lib" directory. Similarly, any classes in "shared/lib" *should* be able to see what's in "common/lib".
<angry-rant>
The crappy, incomplete Tomcat documentation strikes again. One of the bad things about these open source projects is that since no one "owns them" no one has responsibility to work on anything except what they're interested in. The result is often neglected, shoddy and incomplete documentation.
</angry-rant>
So, again, it seems weird that putting the JSTL JARs in "common/lib" works fine while putting them in "shared/lib" doesn't. When I put them in "shared/lib" I get the exception shown below. From the exception below it seems to me that the classes in "common/lib" (e.g., javax.servlet.http.HttpServlet) do not have access to classes in "shared/lib" (e.g., org.apache.taglibs.standard.tag.rt.core.ForEachTag) although the classes in "common/lib" *DO* obviously have access to classes in a web app's "lib" directory.
If only the classloader docs were better....
exception
javax.servlet.ServletException: org.apache.taglibs.standard.tag.rt.core.ForEachTag
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:846)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:779)
org.apache.jsp.index_jsp._jspService(Unknown Source)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.NoClassDefFoundError: org.apache.taglibs.standard.tag.rt.core.ForEachTag
org.apache.jsp.index_jsp.class$(Unknown Source)
org.apache.jsp.index_jsp._jspx_meth_c_forEach_0(Unknown Source)
org.apache.jsp.index_jsp._jspService(Unknown Source)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
----- Original Message ----- From: "Jacob Kjome" <[EMAIL PROTECTED]>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Saturday, January 22, 2005 10:30 AM
Subject: Re: ?? Sharing the JSTL JARS and Classloading ??
Not all libraries are written in a way that allows for them to be used from different webapps. Struts has a statement on this written by Craig McClanahan, but I can't find it at the moment. The gist of it is that Struts (at least with 1.1) cannot be guaranteed to work properly if placed in a shared classloader. One example of where this might be problematic is with non-final static variables. If it they get changed by one app, the other app sees the change. Usually, this is not the desired behavior as it will make each app using the shared library behave in unpredictable ways.
Anyhow, what error are you getting when you add the library to the shared classloader? I haven't looked at the classloader hierarchy in Tomcat for a little while, but it is possible that shared/lib cannot see common/lib, and if there are libraries that standard.jar and jstl.jar depend on libraries that exist in common/lib, then you might get the error you are seeing.
Jake
At 01:24 AM 1/22/2005 -0600, you wrote:
>Hi all,
>
>I'm using TC 5.0.30.
>
>JSTL Is working fine -- I have the standard.jar and jstl.jar files in my
>"WEB-INF/lib" directory.
>
>The problem is that I have several web applications that use JSTL and
>therefore several "WEB-INF/lib" directories. Rather than copy the
>aforementioned JAR files to *every* "WEB-INF/lib" directory I'd rather >put
>them in one central location and have them available for *ALL* web
>applications.
>
>According to the crappy Tomcat documentation that's never updated, I >should
>be able to put the JARs in "$CATALINA_HOME/shared/lib". Unfortunately, >that
>doesn't seem to work with these two JARs for some reason. Instead, I have >to
>put them in $CATALINA_HOME/common/lib (which seems to work, for some
>reason).
>
>Why can't I just put these two JARs in "$CATALINA_HOME/shared/lib" and >have
>them shared across all web applications, as the Tomcat documentation on
>"Classloading" indicates I should be able to? It seems very odd that I >can
>either copy the JARs to every WEB-INF/lib directory *OR* put them in
>$CATALINA_HOME/common/lib, but not put them "$CATALINA_HOME/shared/lib".
>
>
>Thanks....
>
>
>
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