protected override ComposablePartCatalog PrepareCompositionCatalog()        {            InterceptionConfiguration cfg = new InterceptionConfiguration().AddInterceptor(this);            return new InterceptingCatalog(Composition.Catalog, cfg);        }         private static void SubscribeToEventAggregator(object instance)        {            if (!(instance is IHandle)) return;             LogFns.DebugWriteLine(string.Format("Automatically subscribing instance of {0} to EventAggregator.", instance.GetType().Name));            EventFns.Subscribe(instance);        }         object IExportedValueInterceptor.Intercept(object value)        {            SubscribeToEventAggregator(value);            return value;        }

public IEnumerable<Lazy<IContextRequirementSelection, IContextRequirementMetadata>> ContextSelections;

Once the user login, the collection gets populated and when I access to the element with the metadata "Company", the instance is created.

Now, an action in my application load another XAP which also need to use this shared service.

I use the same syntaxe as the one above and MEF gives me a NEW instance of the service with the metadata "Company"

After reading a little bit on this subject, the only possibility seems to be if a new MEF container is created by the application.  

To try to confirm it, I changed for the test purpose the references in my application to add a reference to the assembly hosting the exported service.

Then, when I run the application, both usercontrols share the same instance as expected !

Is this a problem in cocktail or devforce ?

regards,