We propose a caching scheme for saving the results of invocations of read methods at server side. Server side caching helps in reducing load on frequently accessed servers when computing the result is relatively costly. Our model provides strong consistency by using a dependency graph that specifies dependence information among method invocations of an object. We have implemented this scheme as a service in CORBA.

In this paper we propose a protocol for load sharing among a cluster of heterogeneous Unix workstations. Our protocol called the distributed process management protocol (DPMP), not only enables load sharing using nonpreemptive process migration but also seamlessly integrates the processes running on a network of machines. Remote processes can be accessed (for signalling, for example), in the same way as local processes making process migration highly transparent to the users and the applications. DPMP also has built in mechanisms to detect and recover from node and network failures. DPMP can be implemented at either the kernel or the user level. We also describe an implementation of DPMP within the Linux kernel. Preliminary performance studies show that the performance gains obtained by using DPMP are substantial.

The usual way of installing a new version of a software system is to shut down the running program and then install the new version. This necessitates a sometimes unacceptable delay during which service is denied to the users of the software. An online software replacement system replaces parts of the software while it is in execution, thus eliminating the shutdown. While a number of implementations of online version change systems have been described in the literature, little investigation has been done on its theoretical aspects. We describe a formal framework for studying online software version change. We give a general definition of validity of an online change, show that it is in general undecidable and then develop sufficient conditions for ensuring validity for a procedural language.

Abstract The usual way of installing a new version of a piece of software is to shut down the running program and then install the new version. This necessitates a sometimes unacceptable delay during which service is denied to the users of the software. An on‐line software replacement system replaces parts of the software while it is in execution, thus eliminating the shutdown. In this paper, we describe a system for on‐line software version change for software written in the C language. When the change is initiated by the user, the system instantiates a new process with the new version of the software, transfers state from the old process to the new one at an appropriate time, and transfers the control to the new process. The user sees a minimal delay in this switchover.