Managing dependencies across plugins and main app.

[Alex Sukstansky]

In JSPF FAQ there is a statement that if plugins are packed in jars
with all required dependencies included, then each of that plugins
will have its own separate class-loading realm to isolate dependencies
from other plugin.
I mean if of plugin uses some-lib-1.0.jar and other plugin uses
incompatible some-lib-1.2.jar there will be no problems at all. But
what about dependencies of a "main app"? How to isolate plugins from
classes loaded in "parent" classloader? Thanks in advance.

Alex.

[sukst...@gmail.com]

Let me explain steps I've made to encounter problem. My App uses spring 3.0.6.
I've created jspf-plugin and build uber-jar using maven shade plugin. So far so good... Everything works perfectly fine. But after I've added spring 3.1.x dependency into my plugin project I've got

java.lang.IncompatibleClassChangeError: Implementing class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:128)
    at org.codehaus.classworlds.DefaultClassRealm.loadClassDirect(DefaultClassRealm.java:242)
    at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:222)
    at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:145)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at net.xeoh.plugins.base.impl.classpath.ClassPathManager.findSubclassesFor(ClassPathManager.java:216)
    at net.xeoh.plugins.base.impl.classpath.loader.FileLoader.locateAllPluginsAt(FileLoader.java:134)
    at net.xeoh.plugins.base.impl.classpath.loader.FileLoader.loadFrom(FileLoader.java:105)
    at net.xeoh.plugins.base.impl.classpath.ClassPathManager.addFromLocation(ClassPathManager.java:140)
    at net.xeoh.plugins.base.impl.PluginManagerImpl.addPluginsFrom(PluginManagerImpl.java:127)
    at com.xxxxxxxxx.service.EmailMessageStrategyTest.testLoadingPlugin(EmailMessageStrategyTest.java:69)

Sorry, if my question is too "noobie", but never the less :)