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PCMAIL: A distributed mail system for personal computers (RFC0993)

IP.com Disclosure Number: IPCOM000004990D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2001-Jul-13
Document File: 55 page(s) / 70K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D.D. Clark: AUTHOR [+2]

Abstract

Pcmail is a distributed mail system providing mail service to an ar- bitrary number of users, each of whom owns one or more workstations. Pcmail's motivation is to provide very flexible mail service to a wide variety of different workstations, ranging in power from small, resource-limited machines like IBM PCs to resource-rich (where "resources" are primarily processor speed and disk space) machines like Suns or Microvaxes. It attempts to provide limited service to resource-limited workstations while still providing full service to resource-rich machines. It is intended to work well with machines only infrequently connected to a network as well as machines per- manently connected to a network. It is also designed to offer disk- less workstations full mail service.

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Network Working Group David D. Clark (MIT) Request for Comments: 993 Mark L. Lambert (MIT) Obsoletes: RFC-984 December 1986

PCMAIL: A Distributed Mail System for Personal Computers

1. Status of this Document

This document is a discussion of the Pcmail workstation-based distri- buted mail system. It is a revision of the design published in NIC RFC-984. The revision is based on discussion and comment from a variety of sources, as well as further research into the design of interactive Pcmail clients and the use of client code on machines other than IBM PCs. As this design may change, implementation of this document is not advised. Distribution of this memo is unlimit- ed.

2. Introduction

Pcmail is a distributed mail system providing mail service to an ar- bitrary number of users, each of whom owns one or more workstations. Pcmail's motivation is to provide very flexible mail service to a wide variety of different workstations, ranging in power from small, resource-limited machines like IBM PCs to resource-rich (where "resources" are primarily processor speed and disk space) machines like Suns or Microvaxes. It attempts to provide limited service to resource-limited workstations while still providing full service to resource-rich machines. It is intended to work well with machines only infrequently connected to a network as well as machines per- manently connected to a network. It is also designed to offer disk- less workstations full mail service.

The system is divided into two halves. The first consists of a sin- gle entity called the "repository". The repository is a storage center for incoming mail. Mail for a Pcmail user can arrive exter- nally from the Internet or internally from other repository users. The repository also maintains a stable copy of each user's mail state (this will hereafter be referred to as the user's "global mail state"). The repository is therefore typically a computer with a large amount of disk storage.

The second half of Pcmail consists of one or more "clients". Each Pcmail user may have an arbitrary number of clients, typically single-user workstations. The clients provide a user with a friendly means of accessing the user's global mail state over a network. In order to make the interaction between the repository and a user's clients more efficient, each client maintains a local copy of its

Clark Lambert [Page 1]

RFC 993 December 1986

user's global mail state, called the "local mail state". It is as- sumed that clients, possibly being small personal computers, may not always have access to a network (and therefore to the global mail state in the repository). This means that the local and global mail states may not be identical all the time, making synchronization between local and global mail states necessary.

Clients communicate with the repository via the Distributed Mail Sys- tem Protocol (DMSP); the specification for this protocol appears in appendix A. The repository is therefore a DMSP server in addition to a mail end-site...