Laurent, Thanks for the pointers. This is helpful and reinforces what I was
wondering to do (repackage clojure or use serialization) I'll evaluate the
different approaches
Thanks,
Rama
On Monday, July 1, 2013 10:00:07 AM UTC-7, Laurent PETIT wrote:
>
> 2013/7/1 Rama Shenai <rsh...@climate.com <javascript:>>:
> > Hi,
> >
> > I have an OSGI (Karaf) setup where I have two isolated instances of
> Clojure
> > deployed & running in two bundles (within the same JVM),
> > and I am seeing a problem where passing Clojure Objects (such as
> > PersistentArrayMaps) from one clojure bundle to another, breaks clojure
> > interfaces
> > at the receiving end. The two bundles communicate via a OSGI services.
> >
> > The specific problem/example is as follows:
> >
> > Lets say that I have two Clojure bundle instances running in Apache
> Karaf
> > (clj-bundle-A) and (clj-bundle-B)
> >
> > clj-bundle-A registers an interface implementation with the OSGI
> registry.
> > The interface looks like:
> > public interface clojureCall {
> > Object callMethod(Object request);
> > }
> >
> > clj-bundle-B looks up the interface from the OSGI registry and calls the
> > method, the code looks like this:
> > (defn call-bundle-a []
> > ; service is an instance of clojureCall implemented in clj-bundle-a
> > (let [service (lookup-osgi-registry-bundle-a)]
> > ; send a map as a request
> > (.callMethod service {"hello" "world"})))
> >
> >
> > An instance of the PersistentHashMap {"hello" "world"} is sent from
> > clj-bundle-B to clj-bundle-A;
> > However, clj-bundle-A only sees it as a Java object with its clojure
> > interfaces not realized.
> >
> > For example on clj-bundle-A, the passed in argument looks like
> >> (println request)
> > #<PersistentArrayMap {"hello" "world"} <== I would expect it to print
> > {"hello" "map"} instead it is realizing this as a Java object.
> >
> >> (println (type request))
> > clojure.lang.PersistentHashMap <== The type information is saved, but
> the
> > interface is broken
> >
> >> (map? request)
> > false
> >
> >> (instance? java.util.Map request) <== the java interfaces are realized
> >> correctly
> > true
> >
> > I figure that the problem may be related to the two Clojure-Bundles are
> not
> > sharing any classes between them, since they are running in different
> > isolated bundles.
> > I want to have to multiple instances of clojures running so as to run
> > multiple versions of the sample clj file in the same JVM
> >
> > I am wondering if anyone has any suggestions on how to avoid this
> problem.
>
> Hello,
>
> indeed, you have 2 clojure instances in 2 separate classloader
> environments. So they share nothing, even if you might think so,
> misguided by the fact that the fully qualified class names look
> identical.
>
> An interesting solution would be to refactor Clojure to extract all
> the interfaces into a third bundle, then make each clojure instance
> depend on that bundle made only of interfaces. This way, you would be
> able to share objects via their interfaces.
>
> Or else, at the boundaries, you'll have to serialize / deserialize the
> objects to / from edn, even within the same JVM.
>
> HTH,
>
> --
> Laurent
>
> >
> > Thanks,
> > Rama
> >
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