Michael Clarke

The design of a configurable and reconfigurable middleware platform

Summary. It is now well established that middleware platforms must accommodate an increasingly diverse range of requirements arising from the needs of both applications and underlying systems. Moreover, it is clear that to achieve this accommodation, platforms must be capable of both deployment-time configurability and run-time reconfigurability. This paper describes a middleware platform that addresses these requirements. The platform is built using a well-founded lightweight component model, uses reflective techniques to facilitate (re)configuration, and employs the notion of component frameworks to manage and constrain the scope of reconfiguration operations. Importantly, the platform also aims to achieve high performance and a level of standards conformance (e.g., with CORBA and COM). We demonstrate that, despite its high degree of configurability, the platform performs on a par with standard commercial CORBA ORBs.

An architecture for dynamically extensible operating systems

Operating system design has traditionally followed a philosophy in which the system is structured as a fixed set of abstractions and mechanisms. This approach, however, is now showing its limitations in the face of new application areas which demand extensibility and configurability. We describe the design of a dynamically extensible operating system called DEIMOS. DEIMOS is unique in that it does not define a kernel entity. Instead, both traditional kernel functions and application specific services are encapsulated as modules which can be loaded, configured and unloaded on demand (i.e. at run time) by a base system component called the Configuration Manager (which can itself be unloaded). The lack of a kernel gives DEIMOS great scope for flexibility as applications have complete freedom to tailor their execution environment in accordance with their particular needs. Furthermore, applications can dynamically adapt their environment on an ongoing basis and the differing needs of diverse applications can, in many case, be met simultaneously. The paper discusses the architecture of DEIMOS and gives examples of its scope and applicability.

A distributed object platform infrastructure for multimedia applications

Although distributed object computing has developed rapidly over the past decade, and is now becoming commercially important, there remain key application areas inadequately supported by current standards and implementations. This paper describes research aimed at support for one of these areas: distributed soft real-time/multimedia applications. The approach is to provide a low level platform which offers generic middleware services useful for the implementation of a range of multimedia capable distributed object systems. The design of the platform is influenced on the one hand by the real-time/multimedia-oriented computational model of the RM-ODP and on the other hand by recent research results in the efficient engineering of communications systems and operating systems. The platform provides support for quality of service (QoS) and application specific protocols as required by multimedia capable distributed object systems. A novel scheme for flexible QoS specification and management is described. A performance evaluation of the platform is given and a sample application program is presented to illustrate the platforms API.

An Efficient Component Model for the Construction of Adaptive Middleware

Middleware has emerged as an important architectural component in modern distributed systems. Most recently, industry has witnessed the emergence of component-based middleware platforms, such as Enterprise JavaBeans and the CORBA Component Model, aimed at supporting third party development, configuration and subsequent deployment of software. The goal of our research is to extend this work in order to exploit the benefits of component-based approaches within the middleware platform as well as on top of the platform, the result being more configurable and reconfigurable middleware technologies. This is achieved through a marriage of components with reflection, the latter providing the necessary levels of openness to access the underlying component infrastructure. More specifically, the paper describes in detail the OpenCOM component model, a lightweight and efficient component model based on COM. The paper also describes how OpenCOM can be used to construct a full middleware platform, and also investigates the performance of both OpenCOM and this resultant platform. The main overall contribution of the paper is to demonstrate that flexible middleware technologies can be developed without an adverse effect on the performance of resultant systems

CANVIS: context-aware network visualization using smartphones

This paper describes a prototype application which enables the real-time monitoring and visualization of large Wide Area Networks (WANs) using smartphone devices. The techniques employed allow field engineers to rapidly gain access to a large information repository through the use of a camera equipped mobile phone. More specifically, the use of visual codes [11] attached to networking hardware and infrastructure cabling enables the real-time visualization of network traffic and statistics to be triggered by the capturing of images from a personal device. Moreover, the location and orientation of the phone are used as contextual parameters in order to control the specific information to be retrieved. The prototype described in this paper is currently under evaluation by Information Systems Services (ISS) which is responsible for network support across Lancaster University, the student residences network and also a large regional WAN spanning the whole of the North West of England. Our aim was to establish whether or not this user interaction technique could be harnessed for a real world application that would benefit field engineers who are responsible for maintaining a live production network interconnecting tens of thousands of hosts.

Performance and Integrity in the OpenORB Reflective Middleware

Middleware is playing an increasingly central role in the design of modern computer systems and will, we believe, continue to enjoy this prominence in the future. There is, however, a demonstrable need for more openness and flexibility in middleware [1]. We believe strongly that reflective middleware is the right technology to meet these demands. Indeed, there is strong evidence that such platforms are not only significantly more configurable and reconfigurable than conventional platforms, but that they offer better support for software evolution generally [2]. The main goals of OpenORB v2, the system discussed in this extended abstract, are to address what we perceive as the most pressing shortcomings of current reflective middleware platforms. First, performance: in the worst case, this needs to be on a par with that of conventional platforms, and in the best case (e.g. in cut-down configurations) it should be significantly better. Second, integrity: while permitting maximal reconfigurability, it should be possible to control and constrain reconfigurations so that damaging changes are discouraged and/ or disallowed.