Ian Sommerville

Ethnographically-informed systems design for air traffic control

This paper relates experiences of a project where an ethnographic study of air traffic controllers is being used to inform the design of the controllers’ interface to the flight data base. We outline the current UK air traffic control system, discuss the ethnographic work we have undertaken studying air traffic control as a cooperative activity, describe some of the difficulties in collaboration between software developers and sociologists and show how the ethnographic studies have influenced the systems design process. Our conclusions are that ethnographic studies are helpful in informing the systems design process and may produce insights which contradict conventional thinking in systems design.

Socio-technical systems: From design methods to systems engineering

It is widely acknowledged that adopting a socio-technical approach to system development leads to systems that are more acceptable to end users and deliver better value to stakeholders. Despite this, such approaches are not widely practised. We analyse the reasons for this, highlighting some of the problems with the better known socio-technical design methods. Based on this analysis we propose a new pragmatic framework for socio-technical systems engineering (STSE) which builds on the (largely independent) research of groups investigating work design, information systems, computer-supported cooperative work, and cognitive systems engineering. STSE bridges the traditional gap between organisational change and system development using two main types of activity: sensitisation and awareness; and constructive engagement. From the framework, we identify an initial set of interdisciplinary research problems that address how to apply socio-technical approaches in a cost-effective way, and how to facilitate the integration of STSE with existing systems and software engineering approaches.

Cloud Migration: A Case Study of Migrating an Enterprise IT System to IaaS

This case study illustrates the potential benefits and risks associated with the migration of an IT system in the oil & gas industry from an in-house data center to Amazon EC2 from a broad variety of stakeholder perspectives across the enterprise, thus transcending the typical, yet narrow, financial and technical analysis offered by providers. Our results show that the system infrastructure in the case study would have cost 37% less over 5 years on EC2, and using cloud computing could have potentially eliminated 21% of the support calls for this system. These findings seem significant enough to call for a migration of the system to the cloud but our stakeholder impact analysis revealed that there are significant risks associated with this. Whilst the benefits of using the cloud are attractive, we argue that it is important that enterprise decision-makers consider the overall organizational implications of the changes brought about with cloud computing to avoid implementing local optimizations at the cost of organization-wide performance.

Requirements engineering with viewpoints

The requirements engineering process involves a clear understanding of the requirements of the intended system. This includes the services required of the system, the system users, its environment and associated constraints. This process involves the capture, analysis and resolution of many ideas, perspectives and relationships at varying levels of detail. Requirements methods based on global reasoning appear to lack the expressive framework to adequately articulate this distributed requirementsknowledge structure. The paper describes the problems in trying to establish an adequate and stable set of requirements and proposes a viewpoint-oriented requirements definition (VORD) method as a means of tackling some of these problems. This method structures the requirements engineering process using viewpoints associated with sources of requirements. The paper describes VORD in the light of current viewpoint-oriented requirements approaches and shows how it improves on them. A simple example of a bank auto-teller system is used to demonstrate the method.

QoSOnt: a QoS ontology for service-centric systems

This paper reports on the development of QoSOnt: an ontology for quality of service (QoS). Particular focus is given to its application in the field of service-centric systems. QoSOnt is being developed to promote consensus on QoS concepts, by providing a model which is generic enough for reuse across multiple domains. As well as the structure of the ontology itself an example application currently in development - SQRM (service QoS requirements matcher) - is discussed. This application is used to highlight some of the advantages of the ontology including standardisation and the level of machine understanding of QoS specifications which can be achieved.

Integrated requirements engineering: a tutorial

This short tutorial introduces the fundamental activities of RE (requirements engineering) and discusses how it has evolved as a part of the software engineering process. However, rather than focusing on the established RE techniques, the author discusses how the changing nature of software engineering has led to the new challenges in RE. The author then introduces a number of new techniques that helps us to meet these challenges by integrating RE more closely with other systems implementation activities.

Large-scale complex IT systems

The reductionism behind todays software-engineering methods breaks down in the face of systems complexity.

An empirical study of industrial requirements engineering process assessment and improvement

This article describes an empirical study in industry of requirements engineering process maturity assessment and improvement. Our aims were to evaluate a requirements engineering process maturity model and to assess if improvements in requirements engineering process maturity lead to business improvements. We first briefly describe the process maturity model that we used and modifications to this model to accommodate process improvement. We present initial maturity assessment results for nine companies, describe how process improvements were selected and present data on how RE process maturity changed after these improvements were introduced. We discuss how business benefits were assessed and the difficulties of relating process maturity improvements to these business benefits. All companies reported business benefits and satisfaction with their participation in the study. Our conclusions are that the RE process maturity model is useful in supporting maturity assessment and in identifying process improvements and there is some evidence to suggest that process improvement leads to business benefits. However, whether these business benefits were a consequence of the changes to the RE process or whether these benefits resulted from side-effects of the study such as greater self-awareness of business processes remains an open question.

Decision Support Tools for Cloud Migration in the Enterprise

This paper describes two tools that aim to support decision making during the migration of IT systems to the cloud. The first is a modeling tool that produces cost estimates of using public IaaS clouds. The tool enables IT architects to model their applications, data and infrastructure requirements in addition to their computational resource usage patterns. The tool can be used to compare the cost of different cloud providers, deployment options and usage scenarios. The second tool is a spreadsheet that outlines the benefits and risks of using IaaS clouds from an enterprise perspective, this tool provides a starting point for risk assessment. Two case studies were used to evaluate the tools. The tools were useful as they informed decision makers about the costs, benefits and risks of using the cloud.

Schema evolution in OODBs using class versioning

This paper describes work carried out on a model for the versioning of class definitions in an object-oriented database. By defining update and backdate functions on attributes of the previous and current version of a class definition, instances of any version of the class can be converted to instances of any other version. This allows programs written to access an old version of the schema to still use data created in the format of the changed schema.