Colin Low

Integrating communication services

The need for communication services which span multiple communication technologies is growing. Communication services are being developed in three areas: in the public switched telephony networks, on the Internet in the form of integrated multimedia including voice-over-Internet, and in private switched telephony networks in the form of enterprise computer-telephony integration applications. This article shows it is plausible to create unified services which span the Internet and public switched telephony networks, and goes on to describe Nexus, an architecture and prototype for integrated communication services.

Decentralised application placement

The broadening of the Grid architecture to include commercial as well as scientific workloads raises the possibility of commercial datacentres allocating computational resources on demand. The Utility Datacentre provides a large pool of computational resources that are allocated to service applications on request. When a service application consists of several components, these may be allocated physical computational resources which are distributed across the datacentre. The quality of placement determines how well or badly the application consumes finite global resources, such as bandwidth in the network backbone. This paper examines the placement problem, develops metrics for placement quality, and provides a decentralised approach to improving placement quality based on rounds of resource trading.

Distributed 3D audio rendering

This paper discusses the use of audio spatialisation techniques to complement current developments in Voice-over-IP. The result is to create a shared synthetic audio environment in which Voice-over-IP streams from several participants appear to be spatially located. While the intent is to inter-work with multi-user VRML environments, our proposals build on current Internet multimedia proposals and are independent of the user interface used to navigate a virtual space.

Problem-oriented object memory: customizing consistency

This paper presents the notion of problem-oriented object memory, and its realization in a distributed object-based programming system, Penumbra. This system allows location transparent object invocation, object migration and caching. Its distinguishing feature, however, is its support for problem-oriented object sharing.Problem-oriented object memory is an object model that allows exploitation of application specific semantics by relaxing strict consistency in favour of performance.Our work addresses the problem of achieving scalability of shared write-intensive data in an environment of networked workstations. We have successfully applied the presented ideas to the management of a highly demanding telecoms application.