ABSTRACT
Plurix is an object-oriented Operating System (OS) developed for the PC 
platform. Network communication is implemented via Distributed Shared 
Memory (DSM) management using restartable transactions and optimistic 
synchronization. The OS is developed with a proprietary Java compiler 
transforming Java sources into Intel protected mode code. Abandoning 
the hardware independence of Java eliminates loss of performance and 
allows developing the total OS in Java. In this paper we focus on Java 
interfaces offering multiple subtyping in the Plurix OS but our approach 
is applicable to any other strong typing object-oriented language. After 
a short review of the Plurix environment we present how Java interfaces 
are realized efficiently with respect to method dispatch overhead. We 
show how the Java typing rules are realized using pseudo subtyping. 
Furthermore we reveal interesting semantic amiguities of interface reference 
members arising in a persistent DSM. We suggest extended initialization rules 
to overcome these problems. In this context we also introduce meta interface 
descriptors together with a generalized type equivalence check scheme. 

KEYWORDS:
Interfaces, Multiple Subtyping, Java, Persistence, Distributed Shared Memory