Welcome to

Lancaster University's

SUMO Home Page: Support for Multimedia in Operating Systems

Introduction

Over the past few years members of the SUMO team at Lancaster University and CNET, France Telecom have been designing and implementing a microkernel based system with facilities to support distributed real-time and multimedia applications and ODP based multimedia distributed application platforms.

We are interested in both communications and processing support for distributed real-time/ multimedia applications in end systems, and believe that such applications require thread-to-thread real-time support according to user supplied quality of service (QoS) parameters. Such support, depending on the level of QoS commitment required, may require dedicated, per-connection, resource allocation in the CPU scheduler, virtual memory system and communication system. It may also require ongoing dynamic QoS management in all these areas. Another important requirement we have imposed on ourselves is to support standard UNIX applications on the same machine as our real-time/ multimedia support infrastructure; we do not want to build a specialist real-time system that is isolated from the standard application environment. Efficiency is a prime consideration in our work. In particular, we are interested in minimising system imposed overheads by reducing the cost and number of system calls, context switches and copy operations.

To achieve these ends we use the Chorus microkernel as a vehicle for our research (Chorus tech. reports are available here). Chorus lets us run UNIX applications through a SVR4 compatible UNIX 'personality' known as Chorus/MiX, and also provides rudimentary real-time support to native Chorus applications. We have designed our distributed real-time/ multimedia support system as a Chorus 'personality' implemented partly in kernel space and partly as a user level library to be linked with native Chorus applications. The personality provides a QoS driven application programmer's interface (API), connection oriented communications with dedicated, per-connection, resources, and facilities for monitoring and maintaining ongoing QoS levels.

Our approach is structured around a set of key architectural principles:

Recently, we have begun investigating the use of the SUMO system as a support infrastructure for CORBA. We are augmenting the existing CORBA computational model with stream interfaces for multimedia, and QoS annotations on interfaces (along the lines suggested by the ISO's RM-ODP Reference Model for Open Distributed Processing). We are then underpinning the enhanced model with the SUMO real-time functionality.

The intention is to exploit the resulting "real-time CORBA" both in end-systems and on internal nodes in broadband networks. A primary role of real-time CORBA in the network is to serve as a support infrastructure for the implementation of open signalling protocols. This work is part of the OPENSIG research activity managed by Columbia University, New York. The open signalling work is also coordinated with the BT Labs funded Management of Multiservice Networks project of which Lancaster is a member. The project is also closely related to the QoS-A Project at Lancaster. You can find details of this, along with other projects run by the Distributed Multimedia Research Group, here.

Personnel

The SUMO team at Lancaster comprises the following researchers: In addition, Michael Papathomas, now at IMAG Grenoble, has worked on SUMO in the past and is still closely associated with the project.

Papers and Reports

A more detailed description of our work can be found in the literature. In particular, the architectural principles are expanded on in:
Architectural Principles and Techniques for Distributed Multimedia Application Support in Operating Systems
Coulson, G., and G.S. Blair
ACM Operating Systems Review, Vol 29, No 4,pp 17-24, October 1995. (MPG-95-09)

The microkernel API is comprehensively described in:
Micro-kernel Support for Continuous Media in Distributed Systems
Coulson, G., G.S. Blair, and P. Robin
Computer Networks and ISDN Systems 26, pp 1323-1341, 1994. (MPG-93-04)

Supporting Continuous Media Applications in a Micro-Kernel Environment
Coulson, G., G.S. Blair, P. Robin, and D. Shepherd
Architecture and Protocols for High-Speed Networks. Editor: Otto Spaniol, Kluwer Academic Publishers, 1994. (MPG-94-16)

The underlying microkernel based infrastructure is covered in:
Extending the Chorus Micro-kernel to Support Continuous Media Applications
Coulson, G., G.S. Blair, and P. Robin
Proc. 4th International Workshop on Network and Operating System Support for Digital Audio and Video (NOSSDAV), Lancaster, UK, Springer Verlag, pp 49-60, 1993. (MPG-93-20)

The Design of a QoS Controlled ATM Based Communications System in Chorus
Coulson, G., A. Campbell, P. Robin, G. Blair, M. Papathomas, and D. Hutchison
IEEE Journal on Selected Areas in Communications, Special Issue on ATM LANs, Vol 13, No 4, pp 686-699, May 1995. (MPG-94-05)

Further project references are as follows:
Supporting Real-time Multimedia Behaviour in Open Distributed Systems: An Approach Based on Synchronous Languages
Blair, G.S., M. Papathomas, G. Coulson, P. Robin, J.B. Stefani, F. Horn, and L. Hazard
Proc. ACM Multimedia '94, San Francisco, USA, 1994. (MPG-94-13)

Meeting the Real-time Synchronisation Requirements of Multimedia in Open Distributed Systems
Coulson, G., and G.S. Blair
Distributed Systems Engineering Journal (DSEJ), Vol 1, No 1, pp 135-144, 1994. (MPG-92-45)

A Model for Active Object Coordination and its use for Distributed Multimedia Applications
Papathomas, M., G.S. Blair, and G. Coulson
Object-Based Models and Languages for Concurrent Systems, Springer Verlag Lecture Notes in Computer Science, 1994. (MPG-94-23)

A Programming Model and System Infrastructure for Real-Time Synchronisation in Distributed Multimedia Systems
Blair, G.S., G. Coulson, M. Papathomas, J.B. Stefani, F. Horn and L. Hazard
IEEE Journal on Selected Areas in Communications Special Issue on Multimedia Synchronisation, 1995. (MPG-94-21)

Supporting the Real-time Requirements of Continuous Media in Open Distributed Processing
Coulson, G., G.S. Blair, J.B. Stefani, F. Horn, and L. Hazard
Computer Networks and ISDN Systems, Vol 27, No 8, July 1995.(MPG-92-35)

Scheduling and Admission Testing for Jitter Constrained Periodic Threads
Mauthe, A., G. Coulson, G.S. Blair, and D. Hutchison
Proc. Fifth International Workshop on Network and Operating System Support for Digital Audio and Video, Boston, USA, 1995. (MPG-95-04)

Addressing the Real-Time Synchronisation Requirements of Multimedia in an Object-Oriented Framework
Papathomas, M., G.S. Blair, G. Coulson, and P. Robin
Proc. IST&T/SPIE High Speed Networks and Multimedia Computing '95, San Jose, USA, 1995. (MPG-95-8)

Implementing a QoS Controlled ATM Based Communications System in Chorus
Robin, P., G. Coulson, A. Campbell, G. Blair, and M. Papathomas
Proc. Fourth International Workshop on Protocols for High Performance Networks, Vancouver, Canada, 1994. (not on FTP server)

Continuous Media Communications in a Micro-Kernel Environment
Coulson, G., and G.S. Blair
IEEE Second IEEE Workshop on High-Performance Communications Subsystems, Williamsberg, Virginia, 1993. (not on FTP server)

Supporting End-to-End Quality of Service in a Micro-Kernel Environment
Blair, G.S., G. Coulson, P. Robin, and M. Papathomas
Proc. Workshop on Communications and Distributed Systems: New Technologies, New Requirements, Grenoble, France, 1994. (not on FTP server)

All the papers from this project, in addition to those produced by related projects at Lancaster, can be found here. Here are two files for Andrew Campbell: here

SUMO Home Page / Geoff Coulson / geoff@comp.lancs.ac.uk