Sorry, correcting email address. On May 20, 2009, at 4:27 PM, Craig L Russell wrote:
Hi Felix Devs, I'm curious about the issue contained in this thread. My understanding of the issue is this:If an application is running in an OSGi environment and declares a dependency (its OSGI manifest imports the java mail packages) does its context class loader see the javax.mail jar in its entirety? My guess is: not. The OSGi class loader implements the getResources call and filters for exported artifacts.
So, in order for the application to see the META-INF/mailcap.default resource, this file would need to be exported explicitly and then the getResources as implemented by OSGi container would find it.
Similarly, if an OSGi bundle wants to makes its META-INF/services/ some.implemented.Interface file available, the OSGi manifest would have to explicitly export it.
Does the user then need to explicitly name the META-INF/services/ some.exported.Interface in order to access all the implementations via getResources?
Thanks, Craig Begin forwarded message:
From: Peter Williams <[email protected]> Date: May 20, 2009 1:08:15 PM PDT To: [email protected] Subject: Re: OSGi confusion... Reply-To: [email protected] Bill Shannon wrote:I don't know that JAF was expecting to access *EVERY* available jar file (perhaps), but certainly most of them and very likely any of them that actually contained "META-INF/mailcap" would be in the "most of them" list (e.g they won't be in weird agent jars or bootloader stuff, just plain application or library jars).Richard S. Hall wrote:On 5/19/09 4:08 PM, Peter Williams wrote:I'm investigating a JavaMail failure in V3 that is caused by the current OSGi configuration and I'm trying to figure out how to fix it.The issue is this: Code in the JDK (JAF in this case) is calling getResources() on the current context classloader (web app classloader in my test case, but probably could another one) to locate any available mailcap files. It's trying to find META-INF/ mailcap.default in javax.mail.jar. This fails, the code breaks. Outside of OSGi, this all works fine.So what needed to happen here to make this work? Should javax.mail.jar be exporting META-INF? How? Does the JDK have to import this? (how?!)If I understand correctly, it sounds like JAF expects to be able to access every available JAR file by accessing the context class loader. This is a recipe for failure in OSGi.Anyway, see below.Typically, these sorts of situations involve some sort of extender listening for bundles with mailcap files and then the information in them can be injected where appropriate.Unfortunately, I don't know enough about JAF to say in detail how this might work.I can help with JAF if you can help me interpret OSGi.Can you tell me why, even though JAF accessed a classloader that knew about javax.mail.jar, the file at META-INF/mailcap in that jar was not accessible. Is this because javax.mail.jar does not export META-INF? (I had problems attempting this, but I don't have the errors handy right now -- glassfish build issued a bunch of split package warnings though, I'm guessing because META-INF is present in all jars).Assuming the file can be located and processed though, it will contain fully qualified class names for the implementations of a particular public interface. The implementations will be in private packages of javax.mail.jar.Do you think JAF be able to instantiate these classes? If not, they'll need to be exported (e.g. public) too, correct?FWIW, it looks like another company (guess :)) using OSGi is having similar problems, as I ran across their (unresolved) bugs on this issue while research solutions.Thanks -PeterThis is a fairly common pattern in the JDK, and one we've recommended in Java EE for quite a few years. This is essentially the same as java.util.ServiceLoader. It's fine if an OSGi bundle has to explicitly export these classes sothey can be loaded by (e.g.) JAF, but JAF needs to be able to load theseclasses using the context class loader. --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]--------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
Craig L Russell Architect, Sun Java Enterprise System http://db.apache.org/jdo 408 276-5638 mailto:[email protected] P.S. A good JDO? O, Gasp! Craig L Russell Architect, Sun Java Enterprise System http://db.apache.org/jdo 408 276-5638 mailto:[email protected] P.S. A good JDO? O, Gasp!
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