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This document describes the design and implementation of the ADAMS Storage Management System. The system consists of a server that manages connections with multiple clients and passes storage requests to I/O-dedicated processes. The communication channels between clients and the server are implemented through sockets, the basic interprocess communication facility in BSD UNIX+. The interface provided to client programs consists of functions that connect and disconnect the client and server, and operations on an abstract data type called a bag, which is a collection of variable or fixed-length objects. The function interface completely hides the message passing required to support the operations and the connection. Interfaces exist for C and C++ programs. ################## + UNIX is a Trademark of AT&T Bell Laboratories. 1. INTRODUCTION The goal of the ADAMS (Advanced DAta Management System) project [1] is to create a database system that allows processes written in traditional progr...

Lower Layer is an interprocess communication library, designed for exploring the use of object oriented techniques and modern language support in communication programming. Lower Layer provides a unified, yet extensible, programming interface to different communication protocols. Its most remarkable features are: simplicity and ease of use, exhaustive utilization of mechanisms provided by the language (Ada), use of object oriented techniques for clean design and code reuse, portability, and extensibility. Although it is not a main goal, efficiency has also been taken into account in the implementation. The communication model provided by Lower Layer is datagram oriented, with simple best-effort semantics. Special care has been devoted to the support of multicast protocols---hence the datagram model, for instance. If the communication system guarantees some stronger semantics for the delivery of messages, this is also made available to the programmer. Type extension is used for...

The dynamics of large networks is known to be complex. In this paper, we study a characterization of network dynamics in terms of transit times and losses. Applicability of this characterization is studied through experimental evaluation of connections on the Internet using instrumentation at the kernel level as well as at the application level. The results of this study indicate that this characterization is useful and yield several surprising outcomes which are presented. 1 Introduction Modern computer networks such as Internet are characterized by the large number of computers connected in a complex topology and carrying a variety of message traffic. The variability in the traffic and the complex network control algorithms (like routing) lead to a rather involved dynamic behavior. The design of endto -end control algorithm requires the knowledge of network dynamics. Many algorithms in use today, such as flow control in Transmission Control Protocol (TCP) [4], have been designed bas...

This paper describes a simple authentication protocol for use with terminal emulation programs running on small workstations, and communicating with a host computer over a (potentially) insecure network. The technique has the advantage that it requires no more network traffic than would be necessary using a standard user-id/password challenge, and also requires only a small amount of additional intelligence at the workstation. Some management issues are also discussed. The system has been implemented on two host systems and two workstation types

This paper presents the Vartalaap system developed at IIT, Bombay. Vartalaap is an hierarchical distributed system for multicast communication over a network, implemented in a hardware-independent fashion. The multicast is achieved without resorting to unnecessary broadcasting of messages over the network. Issues covered in this paper include the primitives for multicast, the multicast model and the system architecture. We discuss the implementation of Vartalaap and compare it with some other systems. We conclude with a discussion on the limitations of the current implementation and directions for future work. key words : Multicast communication Communication primitives Computer networks Client--server model