| Re: Bundle Ad-Hoc Classloading Options In 3.6, Revisited [message #555356] |
Thu, 26 August 2010 12:12  |
|
Rob Hatcherson wrote:
> The general topic of bundle classloading has been addressed many times,
> so apologies in advance for bringing it up again. Web info on this
> topic often applies to older versions of Eclipse, and it can be
> time-consuming to weed out the old from the new. At this point I'm
> fishing for advice that will keep me from running toward dead ends
> and/or pursuing options for which there are improved alternatives under
> 3.6.
>
> Assume I have defensible reasons for needing my RCP plug-in to load
> ViewPart subclasses from an ad-hoc classpath, so that for all intents
> and purposes those ViewPart subclasses appear as through they were a
> built-in part of my plug-in:
>
> MYCLASSPATH=<using some existing dynamic mechanism, assemble a classpath
> where ViewPart subclasses can be found>
>
> Eclipse/Equinox <- allows ad-hoc ViewPart subclasses loaded by
> MyRcpPlugin to be added to windows/pages
> MyRcpPlugin <- loads ViewPart subclasses from MYCLASSPATH so they
> appear to have come through the bundle's classloader
>
> A custom classloader to load the classes of interest is easy enough;
> what I'm after are recommended ways to inject this into the bundle
> classloading mechanism, under the assumption that pre-building a RCP
> plug-in that already includes the ViewPart subclasses of interest is not
> an option (I may be able to do this in the future, but for now I can't).
>
> There appear to be several mechanisms in 3.6 that *might* do what I
> want, including but not limited to adapter hooks, bundle proxy class
> loaders, and fiddling with OSGi parent classloaders. However, the
> discussion is esoteric, and sometimes is accompanied by words like "but
> we don't recommend that you do this" etc.
>
> Adding on-the-fly contributions to the extension registry seems to be
> working ok. If I can settle on a decent approach to deal with the
> classloading issue - assuming it's even possible through public/approved
> mechanisms - then the rest of what I'm after should fall into place
>
> Any advice?
>
I've re-routed this to equinox, they have a greater understanding of the
OSGi framework and classloading
The only suggestion I have: once you know your classpath, why not
assemble a bundle on the fly (you don't have to jar it up) and then use
BundleContext/PackageAdmin to load it?
the MANIFEST.MF is simple to create, as well as a plugin.xml.
Bundle-ClassPath can refer to jars that exist elsewhere on the system
using the external: scheme
PW
--
Paul Webster
http://wiki.eclipse.org/Platform_Command_Framework
http://wiki.eclipse.org/Command_Core_Expressions
http://wiki.eclipse.org/Menu_Contributions
http://wiki.eclipse.org/Menus_Extension_Mapping
http://help.eclipse.org/galileo/index.jsp?topic=/org.eclipse .platform.doc.isv/guide/workbench.htm
Paul Webster
http://wiki.eclipse.org/Platform_Command_Framework
http://wiki.eclipse.org/Command_Core_Expressions
http://wiki.eclipse.org/Menu_Contributions
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