Distributed heterogeneous systems are being increasingly used to execute a variety of large size simulation and computational problems.
Resource management is one of the most important issues in building such systems.
Jini relies on multicasting across the network for its internal protocols. However, in a distributed environment, such as the one under consideration here, multicasting may not be supported across the subnets for various reasons. In this paper we describe enhancements to Jini required to use it for building a middleware resource management system in a distributed environment that does not support multicasting. In particular, we introduce a lightweight service, called the Tunneling Service, which tunnels multicast messages across the subnets. We have implemented our mechanism and used it to successfully tunnel messages between subnets in a single domain and also between different domains.