[news.eclipse.platform.rcp] Re: how do i set up plugin dependencies

["CL [dnoyeb] Gilbert" <Lamont_Gilbert@xxxxxxxxxxxxxxxxx>]

Raj wrote:
> I have four plugin's in my application
>
> 1) app
> 2) springframework
> 3) apache-commons (commons logging etc)
> 4) log4j
>
> 2,3,4 are setup as dependencies to 1
>
> I am getting a java.lang.NoClassDefFoundError: 
> org/apache/commons/logging/LogFactory error when i try to load my spring 
>  config. Do i have to set up apache commons as a dependecy to 
> spring-framework and log4j as a dependency to apcahe commons and such.

if Plugin 3 requires elements from plugin 2, then plugin 3 needs to 
import plugin 2.  Plugin 3 does not get access to plugin 2 just because 
plugin 1 requires both 3 and 2.

> Since apache commons and logj are available through the class laoder of 
> the main  app, and I am trying to initialize spring through my app is 
> there an easy way to tell my spring plugin look at app for any runtime 
> dependencies.

What makes you think apache commons and log4j are available through the 
class loader of the main app?  Have you tested that?  Unless those 
plugins are infact fragments, then they are not.  Each plugin gets its 
own classloader.  And even if you import plugin 2 into plugin 1, each 
class from plugin 2 used within plugin 1 is still loaded by the 
classloader of plugin 2.


> I am trying to underastand the eclipse plugin way of classpath setup, 
> any help is appreciated.
>
> Thanks
> Raj


I think I pointed you two 2 bugs.  First you need to read the 
classloading bug from start to finish.  Then you would understand this;

You can not use a library that loads classes dynamically such as with 
Class.ForName by wrapping it in a plugin.  If all you want to do is have 
a seperate plugin for your libraries, the simple solution is to make 
plugins 2,3,4 as fragments of 1.

Otherwise all loading and usage of classes of the library from plugin 2, 
would have to be handled exclusively in plugin 2.


CL