This paper presents the Reliable Multicast Protocol (RMP). RMP provides a totally ordered, reliable, atomic multicast service on top of an unreliable multicast datagram service such as IP Multicasting.RMP is fully and symmetrically distributed so that no site bears an undue portion of the communication load. RMP provides a wide range of guarantees.from unreliable delivery to totally ordered delivery, to K-resilient`majority resilient, and totally resilient atomic delivery.These QoS guarantees are selectable on a per packet basis. RMP provides many communication options, including virtual synchrony, a publisher/subscriber model of message delivery, a client/server model of delivery, an implicit naming service, mutually exclusive handlers for messages, and mutually exclusive locks.It has commonly been held that a large performance penalty must be paid in order to implement total ordeting--RMP discounts this. On SparcStationl0's on a 1250 KB/sec Etheruet, RMP provides totally ordered packet delivery to one destination at 842 KB/sec throughput and with 3.1 ms packet latency.The performance stays roughly constant independent of the number of destinations.For two or more destinations on a LAN. RMP provides higher throughput than any protocol that does not use mulficast or broadcast.

This paper presents another iteration in the ongoing CSCW dialogue between the understanding of work and the design of systems to support work. We overview the Locales Framework (and its five aspects of locale foundations, individual views, civic structures, interaction trajectory, and mutuality) as a shared abstraction for both understanding and designing. We describe the use of the framework in a telehealth case study and discuss the implications of the framework for the design of generic toolkit environments, as interpreted in the prototype system called Orbit. We conclude with a critique of the framework and suggestions for further iterations in the dialogue.

Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Bill (2002) Supporting public availability and accessibility with Elvin: experiences and reflections. Computer Supported Cooperative Work, 11 (3-4). pp. 447-474.

This case study explores the nature of work for one group of systems administrators. Their virtual work domain offered little support for collaboration and mechanisms in the physical domain were often used instead. However, the way that group members were able to make sense of their complex virtual work environment suggests a new interpretation of spatial metaphors for the design of collaborative systems. This is one based on 'place' or 'locale', and 'centres', taking into account the observation that people work in multiple social worlds simultaneously, that these social worlds provide a structuring over the work domain, and that the individual draws from this structure elements relevant to their tasks.