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Posted to users@felix.apache.org by Peter Cheung <mc...@hotmail.com> on 2013/10/13 22:54:32 UTC
questions about felix
Dear All I have a standalone java app that embedded felix. I can start it, load bundle and call the method from bundle (using reflection). 1) My first question is, using reflection is not efficiency. I imported the class from bundle to my host app, it popup "ClassCastException", because i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same. Any workaround?2) I am using maven, how to i add bundle dependency to pom.xml? pom.xml seems not searching the felix bundle repository.
Thanksfrom Peter
RE: questions about felix
Posted by Peter Cheung <mc...@hotmail.com>.
Hi All I finally fixed the issues, i have to load the host app into felix first, after that i don't meet the class-casting error.
Thanksfrom Peter
> From: mcheung63@hotmail.com
> To: users@felix.apache.org
> Subject: RE: questions about felix
> Date: Tue, 15 Oct 2013 17:19:00 +0800
>
> Thanks Marcel and Bruce I dont know how to share the interface between my app and bundle, do you have a working example?
> So far my app (embedded felix) can load a bundle and call a function (in bundle) by reflection, but it is very very inconvenience. I have searched google, seems no work around. Any idea?
> Suppose i am developing a bundle rely on another bundle, how can i import that bundle to my maven project? Really can't find anything in google too, please help.
>
> Thanksfrom Peter
>
> > Subject: Re: questions about felix
> > From: marcel.offermans@luminis.nl
> > Date: Sun, 13 Oct 2013 23:55:58 +0200
> > To: users@felix.apache.org
> >
> > On Oct 13, 2013, at 22:54 PM, Peter Cheung <mc...@hotmail.com> wrote:
> >
> > > Dear All I have a standalone java app that embedded felix. I can start it, load bundle and call the method from bundle (using reflection). 1) My first question is, using reflection is not efficiency. I imported the class from bundle to my host app, it popup "ClassCastException", because i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same. Any workaround?2) I am using maven, how to i add bundle dependency to pom.xml? pom.xml seems not searching the felix bundle repository.
> >
> > You cannot "see" classes that are loaded as part of bundles from your app. It does not help to duplicate them either. The best option is to create an interface, add that to your application, expose it as an exported package through the system bundle, and have the class in the bunde import and implement this interface. That way the interface is shared between the app and any bundle that imports it.
> >
> > Hope that helps.
> >
> > Greetings, Marcel
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: users-unsubscribe@felix.apache.org
> > For additional commands, e-mail: users-help@felix.apache.org
> >
>
RE: questions about felix
Posted by Peter Cheung <mc...@hotmail.com>.
Thanks Marcel and Bruce I dont know how to share the interface between my app and bundle, do you have a working example?
So far my app (embedded felix) can load a bundle and call a function (in bundle) by reflection, but it is very very inconvenience. I have searched google, seems no work around. Any idea?
Suppose i am developing a bundle rely on another bundle, how can i import that bundle to my maven project? Really can't find anything in google too, please help.
Thanksfrom Peter
> Subject: Re: questions about felix
> From: marcel.offermans@luminis.nl
> Date: Sun, 13 Oct 2013 23:55:58 +0200
> To: users@felix.apache.org
>
> On Oct 13, 2013, at 22:54 PM, Peter Cheung <mc...@hotmail.com> wrote:
>
> > Dear All I have a standalone java app that embedded felix. I can start it, load bundle and call the method from bundle (using reflection). 1) My first question is, using reflection is not efficiency. I imported the class from bundle to my host app, it popup "ClassCastException", because i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same. Any workaround?2) I am using maven, how to i add bundle dependency to pom.xml? pom.xml seems not searching the felix bundle repository.
>
> You cannot "see" classes that are loaded as part of bundles from your app. It does not help to duplicate them either. The best option is to create an interface, add that to your application, expose it as an exported package through the system bundle, and have the class in the bunde import and implement this interface. That way the interface is shared between the app and any bundle that imports it.
>
> Hope that helps.
>
> Greetings, Marcel
>
>
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> To unsubscribe, e-mail: users-unsubscribe@felix.apache.org
> For additional commands, e-mail: users-help@felix.apache.org
>
RE: questions about felix
Posted by Stijn de Witt <St...@planonsoftware.com>.
>> i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same.
Actually, the classes are not the same. This is weird, but Java defines the identity of a class as the combination of the fully qualified classname + the classloader through which the class is loaded. So classes from different classloaders are always treated as different.
Either move the stuff that needs the class to a bundle that imports the class (probably very difficult) or do what Marcel suggested and make a common interface that is then exported as a framework package.
-Stijn
-----Original Message-----
From: Marcel Offermans [mailto:marcel.offermans@luminis.nl]
Sent: zondag 13 oktober 2013 23:56
To: users@felix.apache.org
Subject: Re: questions about felix
On Oct 13, 2013, at 22:54 PM, Peter Cheung <mc...@hotmail.com> wrote:
> Dear All I have a standalone java app that embedded felix. I can start it, load bundle and call the method from bundle (using reflection). 1) My first question is, using reflection is not efficiency. I imported the class from bundle to my host app, it popup "ClassCastException", because i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same. Any workaround?2) I am using maven, how to i add bundle dependency to pom.xml? pom.xml seems not searching the felix bundle repository.
You cannot "see" classes that are loaded as part of bundles from your app. It does not help to duplicate them either. The best option is to create an interface, add that to your application, expose it as an exported package through the system bundle, and have the class in the bunde import and implement this interface. That way the interface is shared between the app and any bundle that imports it.
Hope that helps.
Greetings, Marcel
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Re: questions about felix
Posted by Marcel Offermans <ma...@luminis.nl>.
On Oct 13, 2013, at 22:54 PM, Peter Cheung <mc...@hotmail.com> wrote:
> Dear All I have a standalone java app that embedded felix. I can start it, load bundle and call the method from bundle (using reflection). 1) My first question is, using reflection is not efficiency. I imported the class from bundle to my host app, it popup "ClassCastException", because i cannot cast a class that loaded from felix to a class that loaded from default class loader, even two classes are the same. Any workaround?2) I am using maven, how to i add bundle dependency to pom.xml? pom.xml seems not searching the felix bundle repository.
You cannot "see" classes that are loaded as part of bundles from your app. It does not help to duplicate them either. The best option is to create an interface, add that to your application, expose it as an exported package through the system bundle, and have the class in the bunde import and implement this interface. That way the interface is shared between the app and any bundle that imports it.
Hope that helps.
Greetings, Marcel
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Re: questions about felix
Posted by Bruce Jackson <Br...@myriadgroup.com>.
Peter
This doesn't sound like the correct approach to be taking. If you load
bundles into felix, then they will be within the scope of their own class
loaded, per the OSGi model, and therefore not 'the same class'.
Thanks
Bruce
On 13/10/2013 21:54, "Peter Cheung" <mc...@hotmail.com> wrote:
>Dear All I have a standalone java app that embedded felix. I can start
>it, load bundle and call the method from bundle (using reflection). 1) My
>first question is, using reflection is not efficiency. I imported the
>class from bundle to my host app, it popup "ClassCastException", because
>i cannot cast a class that loaded from felix to a class that loaded from
>default class loader, even two classes are the same. Any workaround?2) I
>am using maven, how to i add bundle dependency to pom.xml? pom.xml seems
>not searching the felix bundle repository.
>
>Thanksfrom Peter
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