Re: [equinox-dev] getservice throws class cast exception

["Toni Menzel" <tonimenzel@xxxxxx>]

@Neil,
You are right hence i expected the need to include the api inside the bundle as well as a given need.
Many implementations of services include the api as a convinience for the end user.
(they sometimes just want - say - logging and don't care of stupid compdium bundles as reqirement).
As said, this is (often ok) convinience vs.  clean separation.

@Santosh,
rethink the solution of you can and try to pull out the api into a separate bundle.
If you feel pain, use something bnd to easily pull in api into each bundle (the current solution).
Project-wise, you HAVE the api as separate module/project, haven't you ?

Toni

-------- Original-Nachricht --------
> Datum: Fri, 30 May 2008 09:08:58 +0100
> Von: njbartlett@xxxxxxxxx
> An: "Equinox development mailing list" <equinox-dev@xxxxxxxxxxx>
> Betreff: Re: [equinox-dev] getservice throws class cast exception

> Santosh,
> 
> I'm glad you got this working but please bear in mind that it is a
> poor design choice to export an interface from the same bundle that
> provides the service, because it does not truly de-couple the consumer
> from the provider, and it makes it much harder for you to update the
> provider bundle as the implementation of the service evolves. So I
> still recommend that you pull the interface into a third bundle.
> 
> Regards,
> Neil
> 
> On 5/30/08, Santosh Akhilesh <santoshakhilesh@xxxxxxxxxx> wrote:
> >
> > Hi,
> >
> > Thanks I got the problem solved as per your suggestion.
> >
> > However I could make it work with two bundles as per Toni's hint
> >
> > I included the jar in to the bundle one which was registering the
> service,
> > this bundle exported the interface A.
> >
> > In the second bundle I just imported the interface A and retrieved the
> > object and cast to A successfully.
> >
> > Thanks for your help and time.
> >
> > Cheers,
> > Santosh Akhilesh
> >
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> > -----Original Message-----
> > From: equinox-dev-bounces@xxxxxxxxxxx
> > [mailto:equinox-dev-bounces@xxxxxxxxxxx] On Behalf Of
> njbartlett@xxxxxxxxx
> > Sent: Thursday, May 29, 2008 9:02 PM
> > To: Equinox development mailing list
> > Subject: Re: [equinox-dev] getservice throws class cast exception
> >
> > Santosh,
> >
> > You should not include the JAR that contains the interface in the
> > classpath of the two bundles. You should make it into a third bundle
> > and use Import-Package to depend on the interface.
> >
> > When a class is defined independently by two or more classloaders, the
> > resulting classes are considered by the JVM to be different, even if
> > they have exactly the same name and are defined from the same bytes on
> > disk. Therefore you cannot cast an instance of one type into a field
> > of the other.
> >
> > Regards
> > Neil
> >
> > On 5/29/08, Santosh Akhilesh <santoshakhilesh@xxxxxxxxxx> wrote:
> >> Dear All,
> >>
> >>
> >>
> >> I am new to OSGI and Equinox.
> >>
> >>
> >>
> >> I have defined an interface say A, this is defined in a project and
> > exported
> >> as jar
> >>
> >>
> >>
> >> Now I create Two OSGI bundles I include this jar in both the bundles.
> >>
> >>
> >>
> >> >From one bundle I implement the interface A and register the service
> to
> > the
> >> bundle context from second bundle I try to retrieve this service from
> > bundle
> >> context in the activator start function.
> >>
> >>
> >>
> >> I can see that service is retrieved but when I cast it to interface A,
> I
> > get
> >> class cast exception
> >>
> >>
> >>
> >> Any pointer why this happens and how to correct it.
> >>
> >>
> >>
> >> Regards,
> >>
> >> Santosh Akhilesh
> >>
> >> Ph: 9845482201
> >>
> >>
> >>
> >>
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