Comments on: Exposing the boot classpath in OSGi

By: Neil Bartlett

Neil Bartlett — Wed, 16 Sep 2009 12:40:08 +0000

I agree that approaches A/A' are far better than B. For the bundle using these packages it keeps things simple: if you use ANY package (other than java.*) then simply import it! It is up to the deployer or administrator to ensure the packages are supplied from somewhere, in this case from the system bundle.

A good use-case for this technique is when an OSGi Framework is embedded in a larger Java application, e.g. a JEE application server. We can expose classes and interfaces such as the EJB APIs to the OSGi bundles. Again, the bundles simply import package javax.ejb and the deployer sorts out the details.

By: Costin Leau

Costin Leau — Wed, 25 Feb 2009 06:39:21 +0000

@Senthil, please use the dedicated forum (http://forum.springframework.org/forumdisplay.php?f=43)

By: Senthil

Senthil — Wed, 25 Feb 2009 06:30:15 +0000

I am looking at OSGi web extender release version. It is using the Spring core, context etc of alpha version. Could u guide me to correct osgi web bundles depending on released versions of Spring core, context etc?

Thanks,
Senthil

By: Costin Leau

Costin Leau — Mon, 19 Jan 2009 23:31:19 +0000

@Oleg: Thanks for the explanation on Equinox usage inside Eclipse

@Simon: Thanks Simon – I've updated the blog entry with an explanation on how extension bundles can be used (solution A' above).

Cheers and thanks again for the comments!

By: Simon Kaegi

Simon Kaegi — Mon, 19 Jan 2009 21:15:43 +0000

Another fairly elegant solution is to use an empty framework extension bundle that just provides the various potentially versioned exports. The servletbridge uses this technique to expose the servlet api and potentially any other useful packages from the app server.

By: Oleg Zhurakousky

Oleg Zhurakousky — Mon, 19 Jan 2009 21:00:48 +0000

NOTE on Bootdelegation and Eclipse PDE.
To avoid the confusion I wanted to make sure readers are made aware of the following:
When starting Equinox inside the Eclipse a special Launcher (org.eclipse.equinox.launcher) is used. It is started with some Equinox properties where some of them are set by default to their default values. One of such properties is: osgi.compatibility.bootdelegation which (if set to "true" – default) delegates to the parent CL by default if class can not be found regardless if bootdelegation option was enabled. This means that while starting Equinox inside of Eclispe all classes visible to boot class loader (javax.*, org.w3c.* etc…) will be found.
To ensure full compatibility with OSGi and to experiment with botdxelegation option properly set osgi.compatibility.bootdelegation to "false" (i.e., -Dosgi.compatibility.bootdelegation=false) when starting the Equinox inside of Eclipse.