> On 30 Jan 2020, at 00:09, Christopher Schultz <ch...@christopherschultz.net> 
> wrote:
> 
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> 
> Xavier,
> 
> On 1/29/20 3:23 PM, Xavier (Apache) wrote:
>> Hello Tomcat list,
>> 
>> I’m struggling with a classpath problem. I have a webapp deployed
>> under Tomcat. I have setup multiple tests (3 to be exact). They are
>> all running 9.0.20, one under macOS, and the other 2 under Debian
>> (same version for both). My app requires the jar lib to be loaded
>> in a specific order. What I was able to gather so far is that I
>> should do that customisation in myapp/WEB-INF/context.xml (it looks
>> like I don’t need to tell Tomcat to look for that file)
>> 
>> I’m looking for some sample code to better understand how to do
>> it.
>> 
>> So far I tried
>> 
>> <?xml version="1.0" encoding="UTF-8"?> <Context
>> docBase="\webapps\CloudManager"> <Loader
>> className="org.apache.catalina.loader.VirtualWebappLoader"/> 
>> <lib>xxxxxx</lib> <lib>yyyyyy</lib> ... </Context>
>> 
>> xxxxxx and yyyyyy are jar files in myapp/WEB-INF/lib/xxxxxx.jar
>> 
>> but without any luck.
>> 
>> I’m probably missing something obvious, but I just can’t find it.
> 
> Tomcat has no facility to force the loading of specific JARs in a
> specific order. There has been no consensus that e.g. "alphabetic"
> ordering should be enforced. There is no (servlet) spec-defined order,
> either.
> 
> If you have some special libraries that must be loaded before others
> (rather than a complete and total ordering), you can use the
> <PreResources>[1] facility to establish a directory where some
> libraries are loaded first. I suppose you could use many PreResources,
> in order, to achieve a total ordering, but it will be a lot of typing.
> 
> The VirtualWebappLoader has been deprecated for a long time. I can't
> even find the class in any currently-supported branch of Tomcat.
> 
> - -chris
> 
> [1]
> http://tomcat.apache.org/tomcat-9.0-doc/config/resources.html#Nested_Com 
> <http://tomcat.apache.org/tomcat-9.0-doc/config/resources.html#Nested_Com>
> ponents
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Thanks for the pointers Christopher.

Here’s what I have so far, but I don’t understand why it doesn’t work (I get a 
java.lang.ClassNotFoundException for a class that is in the prelib jars)

-I added a directory mywebapp/WEB-INF/prelib with all the jars that should be 
loaded first (the ones that should be loaded after are in the usual 
mywebapp/WEB-INF/lib directory)
-mywebapp/WEB-INF/context.xml contains

<?xml version="1.0" encoding="UTF-8"?>
<Context>
        <Resources>
                <PreResources 
className="org.apache.catalina.webresources.DirResourceSet" 
base=“/WEB-INF/prelib" webAppMount="/WEB-INF/lib" />
        </Resources>
 </Context>
-I also tried with an absolute path for “base” without success (also I’d really 
need a path relative to the webapp or at least the Tomcat installation, is 
base=$CATALINA_BASE/webapps/mywebapp/WEB-INF/prelib” correct?)

Any idea about what I’m doing wrong?

Thanks a lot,

Xavier

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