Michael Katchabaw

Context-aware service selection based on dynamic and static service attributes

Context-aware applications are able to use context, which refers to information about the surrounding environment, to provide relevant information and/or services to the user. A context-aware application may need to make use of existing services (e.g., a print service). There may be several possible choices of services. The context-aware application should be able to discover and select a service that considers context (e.g., current user location). Existing architectures and protocols for service discovery, however, are not suitable for doing so. Contextual information, by its very nature, is dynamic, reflecting the current state and conditions of the application, its user, or its operating environment. Existing architectures and protocols for service discovery, however, tend to assume the world is static, with attributes describing services offered never changing. If attributes are allowed to change, the approaches do not provide the architectural mechanisms required to update them; dynamic attributes with no means of updating are static for all intents and purposes. To support context-aware service discovery and selection, a better approach is required. This paper discusses one possible approach that is based on existing techniques.

Issues in Managing Soft QoS Requirements in Distributed Systems Using a Policy-Based Framework

We address the problem of Quality of Service (QoS) requirements for multimedia applications (e.g., distance education, telemedicine, electronic commerce). These applications need to be able to co-exist with more traditional applications for transaction and data processing and have soft real-time requirements. Unlike most other work in QoS management, we provide a framework that does not require users or application developers to have detailed knowledge of the resources needed and resource scheduling and allocation techniques in use. These underlying details are effectively hidden. In this paper, we describe our strategy, an architecture of services to support the strategy and a prototype.

Making distributed applications manageable through instrumentation

The goal of a management system in a distributed computing environment is to provide a centralized and coordinated view of an otherwise distributed and heterogeneous collection of hardware and software resources. Management systems monitor, analyse and control network resources, system resources, and distributed application programs. Many organizations currently depend on mission-critical distributed applications, a trend that will increase as software engineering tools emerge that make it easier to construct distributed applications. We believe that manageability must be built in to distributed applications from the beginning rather than added in an ad hoc fashion after they have been developed. Just as designing software for usability, testability and maintenance are being addressed in the development process, so must designing for manageability. Application manageability is a research issue of particular interest to us. The work described in this paper focuses on instrumenting processes to allow them to respond to management requests, generate management reports, and maintain information required by the management system. We present an instrumentation architecture to support this, a prototype implementation which includes a class library of standard instrumentation, and a methodology for instrumentation.

Driving resource management with application-level quality of service specifications

Today’s computiug environments are becoming more and more distributed in natureAt the same time, the applications used in these environments are becoming more complicat ed and are being used in more mission critical roles in tke enterprise. Consequently, users’ demands for performance, reliability, and availability are increasing rapidlyTO meet these needs, a high level of quality of service must be delivered to the user. Doing so, however, is not. an easy task. Because of considerable research effort into this area, great strides are being made towards acceptable quality of service solutions. As researchers in this area have recognized, there are still many challenging open problems needing to be address~edOneof themoreintere~t-h%, Yetdifficult challenges is the specification of quality of servicequality of service solutions must handle quality of service specifications as application-level expectations, as opposed to low-level resource reservations. Do-mg so, however. has been proven to be a non-trivial t.adi. To addr=s this problem, we have developed an applicationdriven approach to resource management to support quality of service. Itre present our general strate~v, the design of a solution realizing th-k approach, and a preliminary prototype implementation based on the architecture. We descmbe experiment.ation and e-xperience to date and evaluate our work and its effectivene= b~~ed on these preliminary rcjdts. Finally, we conclude with a summary of our work and outline our plans to evolve it. in the future. l

Supporting dynamic policy change using CORBA system management facilities

Automation of management tasks is an effective counter-measure to the growing complexity of distributed systems. An increasingly popular view redefines the role of the management system to include automated validation and enforcement of policy. This research proposes an architecture for a policy-driven management system which can adapt dynamically to policy change. We show how this architecture can be implemented in a CORBA distributed object computing environment on top of the recently adopted System Management Common Management Facilities.

Usage based service differentiation for end-to-end quality of service management

It is often difficult to ensure that every application in a computing environment receives the level of quality of service required by their users. In such cases, the demand for computing resources to do so simply exceeds the limited supply that is available. To ensure that at least some user applications meet quality of service requirements, service differentiation is one approach growing in popularity. In this approach, preferential service is given to selected applications, while others deemed less important suffer in comparison. Most work in this area bases service differentiation decisions on static information about the applications, such as the name and type of application, the owner of the application, execution time, and the host on which the application was executed. In this paper, we discuss a new approach to service differentiation that takes into consideration dynamic application usage information in service differentiation decisions. In doing so, we can make better or fairer service differentiation decisions that allow more users to enjoy higher levels of quality of service. This is accomplished by ensuring preferential service is given to applications whose users can actually benefit from the improved service, as opposed to those applications that are essentially ignored or in a state that renders them unusable.

Policy-driven fault management in distributed systems

Management policies can be used to specify requirements about the desired behaviour of distributed systems. Violations of policies (faults) can then be detected, isolated, located and corrected using a policy-driven fault management system. Other work in this area to date has focused on network-level faults. We believe that in a distributed system it is more appropriate to focus on faults at the application level. Furthermore, this work has been largely domain-specific-a generic, structured approach to this problem is needed. Our work has focused on policy-driven fault management in distributed systems at the application level. In this paper, we define a generic architecture for policy-driven fault management and present a prototype system based on this architecture. We also discuss experience to date using and experimenting with our prototype system.

Believability Through Psychosocial Behaviour: Creating Bots That Are More Engaging and Entertaining

Creating believable characters or bots in a modern video game is an incredibly challenging and complex task. The requirements for achieving believability are steep, yet the improvements in player engagement, immersion, and overall enjoyment and satisfaction with their experience make this a worthy problem in desperate need of further examination. In this chapter, we examine how the implementation of psychosocial behaviour in bots can lead to believability, and how this translates into new and exciting possibilities for advancing the state-of-the-art in this area.

An emergent framework for realistic psychosocial behaviour in non player characters

This paper introduces a framework for emergent psychosocial behaviour in non player characters in video games. This framework uses concepts behind emergent gameplay to support the mechanics of designer-defined psychological and social concepts, undefined circumstances, and emergence. Based on this framework, a prototype system has been developed. This prototype has been evaluated for realistic emergent behaviour, and has been shown through experimentation to succeed in supporting emergent psychosocial behaviour. The work to date on the framework is encouraging and quite promising for continued work in this area in the future.

Software design patterns for enabling auto dynamic difficulty in video games

Auto dynamic difficulty is the technique of automatically changing the level of difficulty of a video game in real time to match player expertise. In this paper, we describe a collection of software design patterns for enabling auto dynamic difficulty in video games. The benefits of a design pattern approach include more reusability and lower risk compared to traditional ad hoc approaches. We implemented these design patterns as a proof-of-concept prototype system using Pac-Man as a test-bed.