Shibboleth Developers

[Chad La Joie <>]

I'm not sure why you start out by talking about the Tomcat class loading 
mechanism and then switch to the build stuff.

In ant, tasks that take paths using things like pathelement or classpath 
elements just compose a single class path BEFORE the parent operation 
runs.  So, the ordering of items generally doesn't matter.  When the JVM 
kicks off it just searches the whole classpath for the class.

Now, I said it generally doesn't matter which order elements appear in. 
 When it does matter is when you have multiple classes with the same 
name but differing signatures, at which point the JVM just uses 
whichever it finds first.  Don't do this, it's bad (and the extension 
FAQ says not to do it).  :)

So, are you seeing an error, if so what is it?

Tom Scavo wrote:
> According to the Tomcat documentation, a web application loads classes
> and other resources in the following order:
>
> 1. Bootstrap classes of your JVM
> 2. System class loader classes (described above)
> 3. /WEB-INF/classes of your web application
> 4. /WEB-INF/lib/*.jar of your web application
> etc.
>
> So the classloader attempts to resolve unpacked classes and resources
> under /WEB-INF/classes *before* looking in JAR files under
> /WEB-INF/lib.
>
> Thus the build classpath in build.xml is more-or-less correct:
>
>   <path id="build.path">
>     <pathelement path="${classpath}" />
>     <pathelement location="${build}" />
>     <fileset dir="${custom}">
>       <include name="**/*.jar" />
>     </fileset>
>     <fileset dir="${endorsed}">
>       <include name="**/*.jar" />
>     </fileset>
>     <fileset dir="${libdir}">
>       <include name="**/*.jar" />
>     </fileset>
>     <fileset dir="${buildlibs}">
>       <include name="**/*.jar" />
>     </fileset>
>   </path>
>
> We could quibble about the order of the JAR files, but the build
> directory is searched first, which is most important.  (Btw, why is
> ${custom} in this classpath?  This seems like a bug.)
>
> Also in build.xml, when running unit tests, the following classpath is used:
>
>   <classpath>
>     <fileset dir="${custom.libs}">
>       <include name="*.jar"/>
>     </fileset>
>     <filelist refid="test.path"/>
>   </classpath>
>
> where
>
>   <path id="test.path">
>     <path refid="build.path"/>
>     <pathelement location="${tests}"/>
>   </path>
>
> This results in the following search order:
>
> 1) Extension JARs
> 2) Shibboleth classes
> 3) Shibboleth JARs
> 4) Extension classes
>
> which doesn't seem right.  Shouldn't the order be:
>
> 1) Extension classes
> 2) Extension JARs
> 3) Shibboleth classes
> 4) Shibboleth JARs
>
> I'm assuming that Extension classes and JARs should be searched before
> Shibboleth classes and JARS, which seems reasonable.  However, in
> extension-build.xml the build classpath is as follows:
>
>   <!-- Shibboleth Libraries -->
>   <classpath refid="build.path" />
>
>   <!-- Shibboleth Classes -->
>   <classpath>
>     <pathelement location="${build}" />
>   </classpath>
>
>   <!-- Extension libraries -->
>   <classpath>
>     <fileset dir="${ext.lib}">
>       <include name="**/*.jar" />
>     </fileset>
>   </classpath>
>
> That's not right since 1) the second classpath element ${build} is
> redundant, and 2) Shibboleth classes and libraries are searched before
> extension libraries.  The order should be, I think, just the opposite:
>
>   <!-- Extension libraries -->
>   <classpath>
>     <fileset dir="${ext.lib}">
>       <include name="**/*.jar" />
>     </fileset>
>   </classpath>
>
>   <!-- Shibboleth Classes and Libraries -->
>   <classpath refid="build.path" />
>
> Moreover, when running unit tests in extension-build.xml, the
> following pathelement should be inserted at the *beginning* of the
> above list:
>
>   <classpath>
>     <pathelement location="${ext.classes}" />
>   </classpath>
>
> Otherwise JUnit will not be able to find the unit test class files.
>
> Let me know what you think.
>
> Tom

--
Chad La Joie             315Q St. Mary's Hall
Project Sentinel         202.687.0124