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Dive into the research topics where Colin J. Fidge is active.

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Featured researches published by Colin J. Fidge.


IEEE Computer | 1991

Logical time in distributed computing systems

Colin J. Fidge

The partial ordering of events as defined by their causal relationships, that is, the ability of one event to directly, or transitively, affect another is defined. Its generalized and practical implementations in terms of partially ordered logical clocks are described. Such clocks can provide a decentralized definition of time for distributed computing systems, which lack a common time base. In their full generality, partially ordered logical clocks may be impractically expensive for long-lived computations. Several possible optimizations, depending on the application environment in which the clocks will be used, are described. Some applications are summarized.<<ETX>>


data and knowledge engineering | 2009

Workflow simulation for operational decision support

A Anne Rozinat; Moe Thandar Wynn; van der Wmp Wil Aalst; ter Ahm Arthur Hofstede; Colin J. Fidge

Simulation is widely used as a tool for analyzing business processes but is mostly focused on examining abstract steady-state situations. Such analyses are helpful for the initial design of a business process but are less suitable for operational decision making and continuous improvement. Here we describe a simulation system for operational decision support in the context of workflow management. To do this we exploit not only the workflows design, but also use logged data describing the systems observed historic behavior, and incorporate information extracted about the current state of the workflow. Making use of actual data capturing the current state and historic information allows our simulations to accurately predict potential near-future behaviors for different scenarios. The approach is supported by a practical toolset which combines and extends the workflow management system YAWL and the process mining framework ProM.


IEEE Software | 1996

Fundamentals of distributed system observation

Colin J. Fidge

Its difficult to determine event order in distributed systems because of the observability problem. The author discusses this problem and evaluates different strategies for determining arrival order. The author analyzed four time stamping methods to determine their effectiveness in contending with observability problems. Although he focuses on distributed systems, the concepts also apply to any system exhibiting concurrency-the appearance of two or more events occurring simultaneously-including multiprocessor machines and uniprocessor multitasking. Events in this context may be the execution of single machine instructions or entire procedures; the level of granularity is unimportant. To define event order, the author uses the idea of causality-the ability of one event to affect another-because it allows us to reason independent of any particular time frame.


Real-time Systems | 1998

Real-Time Schedulability Tests for Preemptive Multitasking

Colin J. Fidge

When developing multitasking real-time systems, schedulability tests are used to formally prove that a given task set will meet its deadlines. A wide range of such tests have appeared in the literature. This tutorial acts as a guide to the major tests available for preemptive multitasking applications.


business process management | 2008

Workflow Simulation for Operational Decision Support Using Design, Historic and State Information

A Anne Rozinat; Moe Thandar Wynn; Wil M. P. van der Aalst; Arthur H. M. ter Hofstede; Colin J. Fidge

Simulation is widely used as a tool for analyzing business processes but is mostly focused on examining rather abstract steady-state situations. Such analyses are helpful for the initial design of a business process but are less suitable for operational decision making and continuous improvement. Here we describe a simulation system for operational decision supportin the context of workflow management. To do this we exploit not only the workflows design, but also logged data describing the systems observed historicbehavior, and information extracted about the current stateof the workflow. Making use of actual data capturing the current state and historic information allows our simulations to accurately predict potential near-future behaviors for different scenarios. The approach is supported by a practical toolset which combines and extends the workflow management system YAWL and the process mining framework ProM.


business process management | 2012

Predicting Deadline Transgressions Using Event Logs

Anastasiia Pika; Wil M. P. van der Aalst; Colin J. Fidge; Arthur H. M. ter Hofstede; Moe Thandar Wynn

Effective risk management is crucial for any organisation. One of its key steps is risk identification, but few tools exist to support this process. Here we present a method for the automatic discovery of a particular type of process-related risk, the danger of deadline transgressions or overruns, based on the analysis of event logs. We define a set of time-related process risk indicators, i.e., patterns observable in event logs that highlight the likelihood of an overrun, and then show how instances of these patterns can be identified automatically using statistical principles. To demonstrate its feasibility, the approach has been implemented as a plug-in module to the process mining framework ProM and tested using an event log from a Dutch financial institution.


mathematics of program construction | 1998

A Set-Theoretic Model for Real-Time Specification and Reasoning

Colin J. Fidge; Ian J. Hayes; Andrew P. Martin; Axel Wabenhorst

Timed-trace formalisms have emerged as a powerful method for specifying and reasoning about concurrent real-time systems. We present a simple variant which builds methodically on set theory, and is thus suitable for use by programmers with little formal methods experience.


international conference on quality software | 2009

Security Metrics for Object-Oriented Class Designs

Bandar Alshammari; Colin J. Fidge; Diane Corney

Measuring quality attributes of object-oriented designs (e.g. maintainability and performance) has been covered by a number of studies. However, these studies have not considered security as much as other quality attributes. Also, most security studies focus at the level of individual program statements. This approach makes it hard and expensive to discover and fix vulnerabilities caused by design errors. In this work, we focus on the security design of an object-oriented application and define a number of security metrics. These metrics allow designers to discover and fix security vulnerabilities at an early stage, and help compare the security of various alternative designs. In particular, we propose seven security metrics to measure Data Encapsulation (accessibility) and Cohesion (interactions) of a given object-oriented class from the point of view of potential information flow.


business process management | 2007

Access control requirements for processing electronic health records

Bandar Alhaqbani; Colin J. Fidge

There is currently a strong focus worldwide on the potential of large-scale Electronic Health Record systems to cut costs and improve patient outcomes through increased efficiency. A number of countries are developing nationwide EHR systems to aggregate services currently provided by isolated Electronic Medical Record databases. However, such aggregation introduces new risks for patient privacy and data security, both by linking previously-separate pieces of information about an individual, and by creating single access points to a wide range of personal data. It is thus essential that new access control policies and mechanisms are devised for federated Electronic Health Record systems, to ensure not only that sensitive patient data is accessible by authorized personnel only, but also that it is available when needed in life-critical situations. Here we review the traditional security models for access control, Discretionary Access Control, Mandatory Access Control and Role-Based Access Control, and use a case study to demonstrate that no single one of them is sufficient in a federated healthcare environment. We then show how the required level of data security can be achieved through a judicious combination of all three mechanisms.


business process management | 2007

Business process simulation for operational decision support

Moe Thandar Wynn; Marlon Dumas; Colin J. Fidge; Arthur H. M. ter Hofstede; Wil M. P. van der Aalst

Contemporary business process simulation environments are geared towards design-time analysis, rather than operational decision support over already deployed and running processes. In particular, simulation experiments in existing process simulation environments start from an empty execution state. We investigate the requirements for a process simulation environment that allows simulation experiments to start from an intermediate execution state. We propose an architecture addressing these requirements and demonstrate it through a case study conducted using the YAWL workflow engine and CPN simulation tools.

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Moe Thandar Wynn

Queensland University of Technology

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Yu-Chu Tian

Queensland University of Technology

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Arthur H. M. ter Hofstede

Queensland University of Technology

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Diane Corney

Queensland University of Technology

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Lin Ma

Queensland University of Technology

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Wayne Kelly

Queensland University of Technology

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Bandar Alhaqbani

Queensland University of Technology

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Bandar Alshammari

Queensland University of Technology

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Tony Sahama

Queensland University of Technology

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Yong Sun

Queensland University of Technology

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