A Generic Multicast Transport Serviceto Support
Disconnected Operation
Silvano Maffeis, maffeis@acm.org
Walter Bischofberger, bischi@ubilab.ubs.ch
Kai-Uwe Mätzel, maetzel@ubilab.ubs.ch
Department of Computer Science, Cornell University,
and UBILAB, Union Bank of Switzerland
Abstract
Many mobile computing applications can profit from process groups and
reliable multicast communication to maintain replicated data, but most
operating systems available today fail in providing the primitive
operations needed by such applications. In this paper we describe a
highly configurable, Generic Multicast Transport Service (GTS), which
supports the implementation of group-based applications in wide-area
settings. GTS is unique in that it offers fault-tolerant,
order-preserving multicast on arbitrary communication protocols,
including e-mail. As another distinguishing mark, messages can be sent
to processes even when they are temporarily unavailable, which permits
disconnected operation and mobility. We further propose an
object-oriented system design consisting of adaptor objects
interconnected to form a protocol tree. Adaptor objects offer a common
interface to dissimilar communication protocols, and make it easy to
incorporate new protocols into GTS. Currently, GTS is being used in a
cooperative software engineering environment and in other
projects. GTS is available for anonymous ftp.
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