The usage rate of hardware resources in a computing system is the single largest influence on power consumption that can be impacted by software. Approaches to energy efficient scheduling on private clouds are not suitable for all situations, i.e. particularly when that approach is to consolidate VMs on as few machines as possible, a strategy that while reducing energy usage also impacts performance and dependability. In this paper, we introduce the concept of Workload Mixes, a technique for assigning tasks to compute nodes with the aim of balancing the trade-off between system properties such as energy consumption and application performance. In this paper workload mixes are demonstrated through a series of experiments to affect both system energy consumption and application performance in a virtualized environment. The exploitation of these effects may lead to an energy efficient, performance and dependability aware scheduler for a private cloud computing platform.

Software as a Service (SaaS) is an increasingly attractive option for delivering software functionality. Software vendors act as service providers provisioning the functionality directly via the Internet, and customers pay for access to the service on a flexible billing model such as subscription or pay-per-use. As a result, the generated revenue is difficult to analyse due to the highly dynamic nature of the customer's interaction with the service. We present the Services2Cloud framework to assist service providers in the analysis of their expected revenue based on customer subscription and service usage. Our approach is based on a formal specification of the service on offer and a concise expression of the service usage as probabilistic patterns which are interpreted as stochastic processes. Key features of our theoretical framework have been implemented within a web-based toolkit that aims to facilitate the revenue analysis process for service providers.

In Cloud Computing platforms the addition of hardware monitoring devices to gather power usage data can be impractical or uneconomical due to the large number of machines to be metered. CloudMonitor, a monitoring tool that can generate power models for software-based power estimation, can provide insights to the energy costs of deployments without additional hardware. Accurate power usage data leads to the possibility of Cloud providers creating a separate tariff for power and therefore incentivizing software developers to create energy-efficient applications.

SUMMARY Cloud computing promises a radical shift in the provisioning of computing resources within the enterprise. This paper describes the challenges that decision makers face when assessing the feasibility of the adoption of cloud computing in their organizations, and describes our Cloud Adoption Toolkit, which has been developed to support this process. The toolkit provides a framework to support decision makers in identifying their concerns, and matching these concerns to appropriate tools/techniques that can be used to address them. Cost Modeling is the most mature tool in the toolkit, and this paper shows its effectiveness by demonstrating how practitioners can use it to examine the costs of deploying their IT systems on the cloud. The Cost Modeling tool is evaluated using a case study of an organization that is considering the migration of some of its IT systems to the cloud. The case study shows that running systems on the cloud using a traditional ‘always on’ approach can be less cost effective, and the elastic nature of the cloud has to be used to reduce costs. Therefore, decision makers have to model the variations in resource usage and their systems' deployment options to obtain accurate cost estimates. Copyright © 2011 John Wiley & Sons, Ltd.

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.

Society is challenging systems engineers by demanding ever more complex and integrated systems. With the rise of cloud computing and systems-of-systems (including cyber-physical systems) we are entering an era where mission critical services and applications will be dependent upon `coalitions-of-systems'. Coalitions-of-systems (CoS) are a class of system similar to systems-of-systems but they differ in that they interact to further overlapping self-interests rather than an overarching mission. Assessing the sociotechnical risks associated with CoS is an open research question of societal importance as existing risk analysis techniques typically focus on the technical aspects of systems and ignore risks associated with coalition partners reneging on responsibilities or leaving the coalition. Through a case study of a cloud IT infrastructure migration we demonstrate that responsibility modeling based risk analysis enables the identification of these risks by exploring hazards that may arise when relying upon a coalition of human/organizational/technical agents to provision a service.

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, computersupported 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.

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.

This paper proposes a novel approach to System of Systems modelling based on the specification of system capabilities. The approach is designed to help end users graphically identify and analyse the hazards and associated risks that can arise in complex socio-technical System of Systems, with particular emphasis on the role of system dependencies. Through a case study this paper shows how the technique can identify the vulnerabilities that may arise within a given System of System configuration; and explore the resilience of a given system when considering evolution and unexpected circumstances.

This paper aims to present an ontology model of software engineering to represent its knowledge. The fundamental knowledge relating to software engineering is well described in the textbook entitled Software Engineering by Sommerville that is now in its eighth edition (2004) and the white paper, Software Engineering Body of Knowledge (SWEBOK), by the IEEE (203) upon which software engineering ontology is based. This paper gives an analysis of what software engineering ontology is, what it consists of, and what it is used for in the form of usage example scenarios. The usage scenarios presented in this paper highlight the characteristics of the software engineering ontology. The software engineering ontology assists in defining information for the exchange of semantic project information and is used as a communication framework. Its users are software engineers sharing domain knowledge as well as instance knowledge of software engineering.

This paper discusses Tracker, a framework for meeting management. Many meeting support tools and groupware tools now implement the second generation DR protocols characterized by cheap capture and rich multimedia content. Managing such content requires the manual introduction of annotations to support efficient retrieval. However, to do this in a truly useful manner, the capture and management of these documents (decisions rationale) should encompass not only the annotation of the multimedia content for playback, but should support the extraction of relevant information at the level of semantics and pragmatics: i.e. they should be able to automatically extract information such as what subjects were discussed, what decisions were made, what tasks were assigned. We demonstrate how to achieve such an endeavor in this paper.

In this paper we report on an ethnographic study of a small software house to discuss the practical work of software testing. Through use of two rich descriptions, we discuss that 'rigour' in systems integration testing necessarily has to be organisationally defined. Getting requirements 'right', defining 'good' test scenarios and ensuring 'proper' test coverage are activities that need to be pragmatically achieved taking account of organisational realities and constraints such as: the dynamics of customer relationships; using limited effort in an effective way; timing software releases; and creating a market. We discuss how these organisational realities shape (1) requirements testing; (2) test coverage; (3) test automation; and (4) test scenario design.

In the creative environment where research takes place not everything can be improved. The creative "essence" of research must be undisturbed while "accident" wasted effort is reduced to a minimum. In this paper we discuss the types of knowledge at play in the research environment, introduce a new abstract model of knowledge, and using the model explain how we should focus our effort on research students and on particular types of knowledge transfer in order to gain an over all improvement in our research processes. Just as we teach to facilitate student learning, so too can we supervise, teach and guide to facilitate better and faster researching in our academic computer science departments.

The annual U.K. e-Science All Hands Meeting (AHM) is the premier e-Science conference held regularly in the United Kingdom.Supported mainly by the U.K. e-Science Core Programme, with sponsorship from the Joint Information Systems Committee and from industry, the AHM provides a forum for the e-Science community to present and demonstrate their research, exchange ideas and socialize.The AHM typically attracts approximately 600 participants from academia, industry and commerce, with a technical programme of keynote presentations, regular sessions, workshops, poster sessions and birds-of-a-feather meetings.The term 'e-Science' was first coined by Sir John Taylor, then Director General of the Research Councils, who said that 'e-Science is about global collaboration in key areas of science and the next generation of infrastructure that will enable it'.Such collaboration often takes place through the secure sharing of resources distributed across multiple partners, which has led Foster and Kesselmann to formulate the concept of the Virtual Organization.The Grid is a closely-related concept that refers to the distributed hardware, software and data that are often used to support collaboration.As the AHMs have developed, they have adopted a broad interpretation of what is meant by e-Science, and that is reflected in the papers selected for this special issue. CONTENTSThe third All Hands Meeting (AHM 2004), held 31 August-2 September 2004 at the East Midlands Conference Centre in Nottingham, featured 130 oral presentations spread across five workshops and 24 regular sessions.This special issue contains extended versions of selected papers from AHM 2004 with the aim of highlighting some of the most innovative and interesting research of the U.K. e-Science community.The papers cover a spectrum from fairly generic middleware to specific applications, although many of the papers report on how middleware is used to support a particular application (or class thereof).A good example of this latter type of paper is 'Developing LHCb Grid software:

This paper describes a model that defines the attributes of domestic systems that lead to system dependability and a user-oriented specification method for support systems based on this model. We start by discussing technical dependability models and discuss how these have to be extended for use in a domestic context. We present an extended dependability model based on a socio-technical perspective. This extends the technical notion of dependability to take into account fitness for purpose, acceptability and adaptability. We then go on to discuss MDDS - a questionnaire-based method that reflects the socio-technical dependability model. It is intended for use by social care professionals who are specifying and designing support systems for older or disabled people. MDDS provides a basis for examining a design from a dependability perspective. We illustrate the use of the method and conclude with a discussion of its qualitative evaluation.

It is through our mental models of the world that we understand it. Advances in science are nothing more than improvements to the model. This paper presents the development and refinement of our model of the research process as we seek to understand and improvement the process through three generations of case studies. We conclude by introducing an approach to help manage and plan research projects.

As a branch of engineering cybernetics, automatic control theory has been extensively applied to improve product, increase productivity and rationalize management. As a first try, this paper intends to adapt the principles of conventional control theory to the field of software process, and use them to define a requirement process control system, its dynamic and steady-state performance, and steps in designing, analyzing and improving such a system. Preliminary studies show that more requirements engineering (RE) process activities relating to measuring elements, including those in feedback compensation and organization support, need to be introduced, recommended and selected. The results of this research can be used to guide the establishment and improvement of RE processes, compare different requirement process solutions quantitatively, develop methods for evaluating benefits from process improvements, and structure the application of knowledge about RE.

In this article the author discusses the problems of software construction by configuration and explains why this is a challenging area for software engineering researchers. The author believes that the software maintenance research community has a key role to play in this research. Although much maintenance research has been focused on code and code analysis, the community has addressed issues of dealing with software without specifications and where the internal workings are not readily understandable. Some maintenance tools and techniques, such as program visualization, point the way to effective support for construction by configuration. The author concludes by setting out a research agenda that allows the research community to play an active part in addressing the 21st century software engineering problems.

In this paper, we discuss how mutual influences (e.g. conflicts) of different stakeholder concerns can be detected and reasoned about through composition and stepwise refinement. Some concepts from the aspect-oriented software development paradigm are used to support the composition-centric approach.

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.

Patterns of Cooperative Interaction are regularities in the organisation of work, activity, and interaction among participants, and with, through, and around artifacts. These patterns are organised around a framework and are inspired by how such regularities are highlighted in ethnomethodologically-informed ethnographic studies of work and technology. They comprise a high level description and two or more comparable examples drawn from specific studies. Our contention is that these patterns form a useful resource for reusing findings from previous field studies, for enabling analysis and considering design in new settings. Previous work on the relationship between ethnomethodology and design has been concerned primarily in providing presentation frameworks and mechanisms, practical advice, schematisations of the ethnomethodologist's role, different possibilities of input at different stages in development, and various conceptualisations of the relationship between study and design. In contrast, this article seeks to first discuss the position of patterns relative to emergent major topics of interest of these studies. Subsequently it seeks to describe the case for the collection of patterns based on findings , their comparison across studies and their general implications for design problems, rather than the concerns of practical and methodological interest outlined in the other work. Special attention is paid to our evaluations and to how they inform how the patterns collection may be read, used and contributed to, as well as to reflections on the composition of the collection as it has emerged. The paper finishes, first, with a discussion of how our work relates to other work on patterns, before some closing comments are made on the role of our patterns and ethnomethodology in systems design.

This paper presents patterns of cooperative interaction derived from ethnographic studies of cooperative work as devices for generalisation, re-use and design. These patterns consist of examples of similar social and interactional phenomena found in different studies that serve as resources for defining and envisaging design concepts, and potential work process and technical solutions. We outline new pattern examples and demonstrate their use in application to a complex setting: e-government in local government planning

This paper aims to identify the main dependability properties (and related properties) that can play a part within P2P systems. This, in turn, can be used to help inform the creation of more dependable systems. Given the influence the choice of architecture can have, this paper first provides an overview of the main P2P architectures, before going on to identifying the different properties. Future work will provide a detailed analysis of the effect the architectures can have on these properties.

This paper considers the potential of using patterns of cooperative interaction to support the development of general design principles drawn from a range of work settings. It reports on the development of patterns from ethnographic studies in a number of work environments. Our particular interest is in the possibilities surrounding the use of patterns as a means of organising, presenting and representing this growing corpus of ethnographic material and in the contribution this might make to CSCW design. In this paper we focus on outlining some of our experiences and difficulties in developing patterns from ethnographic studies and present some initial ideas towards the development of a pattern language to exploit the experience gained from a decade of field studies.

The authors describe a study of the social dynamics of new media in Scottish households. The evolving project drew on dialogues with multiple household members elicited in group conversations. This approach to interviews captured different and conflicting points of view, a feature shared with certain social approaches to systems design. Analysis of the interview transcripts revealed that there are recurrent narratives and behavioral genres across households (and across sample groups), and that these reflect tactics, stratagems, and plans by means of which respondents navigate social space. The authors' approach contrasts with prevailing “needs and uses” models in information science, in offering a methodological framework based on group narrative and genre analysis that contributes to a theory of social informatics in the household.

Over a number of years, we have been involved in investigations into using workplace observation to inform requirements for complex systems. This paper discusses how our work has evolved from ethnography with prototyping through presentation of ethnographic fieldwork, to developing a method for social analysis that has been derived from our experience of applying ethnographic techniques. We discuss the strengths and weaknesses of each of these approaches with a particular focus on our most recent work in developing the Coherence method. This method is based on a fusion of viewpoint-oriented and ethnographic approaches to requirements engineering and uses an industry-standard notation (UML) to represent knowledge of work. We use a common example of an air traffic control system to illustrate each approach.

This article is concerned with how to represent in system design the kinds of features of work settings as reported by ethnographic studies of work. Various researchers and practitioners have found that ethnomehodological analyses of work settings can provide useful insights to the work processes and settings in which system design is interested. Previously at Lancaster University, we examined ways in whisk ethnography can be used in h e design process and how the results of ethnographic analyses can be presented in such a way as to be useful components of the design process. This article reflects an effort to approach these methodological issues from a different perspective. It examines how the lessons learned from ethnographic studies can be reflected in the design process itself and in particular how standardized design artifacts (e.g., models, documents) can express the type of information that ethnographic studies produce. The article focuses on how ethnographic analyses can influence the main representational artifact in systems design—the model of the system being developed. We examine how the Unified Modeling Language for object-oriented design can be used to express information about awareness in cooperative systems.

Discusses the notion of software process inconsistency and suggests that inconsistencies in software processes are inevitable and sometimes desirable. We present an approach to process analysis that helps discover different perceptions of a software process and that supports the discovery of process inconsistencies and process improvements stimulated by these inconsistencies. By analogy with viewpoints for requirements engineering that allow multiple perspectives on a software system specification to be managed, we have developed the notion of process viewpoints that provide multi-perspective descriptions of software processes. A process viewpoint includes a statement of focus or "world view", a set of sources of process information, a process description and a set of organizational concerns that represent goals or constraints on the process analysis. We present a description and rationale of process viewpoints, discuss the process of applying process viewpoints for process understanding, and illustrate the overall approach using part of a case study drawn from industrial processes that are part of a safety-critical system development.

Some systems failures are due to defects in manufacturing and design, however that there are a significant number of system failures which result from errors, omissions and inconsistencies in the system requirements. We thus need methods to support a 'safe' requirements engineering process whose objectives are to specify system requirements such that system states which compromise safety are avoided and to include, along with the requirements, a justification or safety case which explains why the specified system is indeed safe. This paper describes the extension of a viewpoint-based requirements method to incorporate safety analysis.

Staff and students at Lancaster University have, for the past five years, been involved in the development of an autonomous robot excavator LUCIE (Lancaster University Computerised Intelligent Excavator). The aim of the project is to add autonomy in order to produce a robot excavator with the following characteristics: it should concentrate on the task of trenching; it should adapt to different soil types without human intervention; it should cope with obstructions; and it should eventually be a self-contained system with no cables to external computers. The hardware and software architectures, optical distance sensor, and safety problems are described.

We argue that the industrial development of interactive systems has to recognise the social dimension of work if these systems are to fully meet the real needs of their users. Under current approaches this depends on whether an individual requirements engineer implicitly applies a user centred approach, recognises the importance of cooperation and is sufficiently sympathetic and intuitive to understand the work and reflect this in the system requirements. We wish to move beyond this by allowing for the provision of a more systematic incorporation of the social dimensions of work. To this end we focus on developing a novel approach to the presentation of ethnographic material. Our approach is based on the use of number of viewpoints and is embodied within a general hypertext tool.

This paper discusses an innovative experiment where sociologists were actively involved in the requirements analysis for an interactive software system to support the work of air traffic controllers. Air traffic control is intrinsically cooperative and our work involved an analysis of that process from a social perspective and the development of a prototype user interface for air traffic controllers’ interaction with a flight information system. As part of the analysis process, sociologists were involved in ethnographic studies of work and discovered subtle and complex patterns of cooperation which, we suspect, would not have been discovered using structured methods for requirements analysis. From a software development perspective, we describe how the input from the sociologists was essential for understanding the real automation requirements, discuss the difficulties of inter-disciplinary cooperative working and suggest how social analysis can be integrated in the interactive systems design process.

Experiences from an interdisciplinary project involving software engineers and sociologists are reported. The project is concerned with discovering the requirements of a user interface to a flight database which is used to provide real-time information to air-traffic controllers. The sociologists are conducting an ethnographic analysis of the activity of air-traffic control, and this is being used for the development of a prototype system. An overview of the project is given, the contribution of sociologists to requirements engineering is discussed, and tool support which will allow ethnographic observations to be integrated into the requirements engineering process is suggested.>

Tools which provide graphical editing techniques for the design of user interface presentations are increasingly commonplace. Such tools vary widely in the mechanisms used to define user interfaces and while some are general purpose, others are targeted at particular application domains. Designers faced with varying requirements must choose one tool and live with its shortcomings, purchase a number of different tools, or implement their own. The paper describes an approach to facilitating the latter by providing a library of augmented user interface components called MOG objects which embody both end-user and editing semantics. User interface design tools based on this approach need only provide mechanisms for composing MOG objects into user interfaces and the addition of any other, higher-level functionality. MOG-based user interfaces retain an in-built editing capability and are inherently tailorable.

The paper reviews some aspects of a research project in which ethnographic studies of air traffic controllers at work were used to inform the design of an electronic flight strip. In particular, it emphasises the important role of ethnography in gaining an insight into the fine grained and often ‘invisible’ aspects of work which are essential to its accomplishment and which must be taken account of in the design process. The paper also reviews some of the practical lessons of interdisciplinary working and the role, along with some limitations, that ethnographic studies can play in the system design process.

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. KEYWORDS Air Traffic Control, Systems Design, Ethnography INTRODUCTION One of the most significant influences of CSCW has been to lend a respectability amongst software developers to sociological methods of empirical research. The contribution of sociology, and anthropology, is through the de...

A range of architectures have emerged which support realtime cooperative user interfaces. These architectures have tended to centralise the management of the interface and thus provide only limited support for user-centred development and interface tailoring. This paper considers the problems associated with the development of tailorable cooperative interfaces and proposes an architecture which allows such interfaces to be developed using an incremental, user-centred approach. The architecture presented in this paper has emerged within the context of a project investigating cooperative interface development for UK air traffic control. We conclude that the architecture is equally applicable to other Command and Control domains, where a shared information space forms the focus for the work taking place. KEYWORDS Multi-user interfaces, CSCW architectures, Command and Control systems, Database visualisation. INTRODUCTION The merging of computer and communications technology and the develop...

This paper describes a system which provides the user with a powerful tool to aid system understanding and supports automatic building of software systems from the language description. It is based on a language for describing software system structure in terms of its components. The system is part of the Eclipse integrated project support environment and comprises the following; a language for describing system structure, a viewing system providing a facility of examine language scripts in a structured way, a version handling system and a system building facility. The principal novel characteristic of the SySL system is that target are build from a logical rather than a physical structure description.

Abstract This paper describes the user interface facilities of the ECLIPSE integrated project support environment. This interface is based on a consistent metaphor called the ‘control panel’ metaphor and includes standard help and message‐handling systems. The paper describes these as well as some of the interface standards which have been developed. The interface has been implemented on top of the ‘applications interface’, which provides a portable, hardware‐independent interface for software tools.

This paper describes a tool for descriptive text processing which can, after tuition by the user, split entity descriptions into their constituent parts and associate a meaning with each of these parts. The program, in essence, is a form of parser generator where the class of texts which may be parsed are those descriptions which are set out in a semi-structured way. Examples of such descriptions are catalogue entries in an electronic components catalogue, descriptions of flora in a handbook of wild flowers and descriptions of drugs in a formulary. Our system is novel in that the user need not analyse the structure of descriptions in advance and then describe that structure in a formal way. Rather, DSA (Description Structure Analyser) dynamically ‘learns’ the structure of descriptions by interacting with the user, who tells DSA what each part of a typical description means. The description model built by DSA is then refined by seeking user advice whenever an unfamiliar description occurs. The system is not restricted to the processing of rigidly structured descriptions. It can create a parser to analyse descriptions which have a variable structure and can even tackle simple sentences of natural language.

Abstract This paper describes a software sysem (SOFTLIB) that has been developed to assist in the management of software documentation generated during systems development projects. It provides facilities to manage large numbers of documents, to file documents when they are complete and to issue them to system developers and maintainers. It also includes an information retrieval facility that allows programming staff to find documents, to examine their contents before issue and to assess the state of the software project documentation. SOFTLIB is explicitly intended to help manage the documentation generated during software development — it is not designed for use by end‐users of that software or for managing end‐user documentation. The novel characteristic of this system is the approach that is taken to the consistency and completeness of documentation. The documentation associated with a software system is organized in such a way that it may be detected if document sets are complete (that is, if all documentation which should be provided for a software component is available) and if document sets are likely to be inconsistent. This means that if a document has been changed without a comparable change being made to other associated documents, this is detectable by the librarian system. In addition, a subsidiary aim of our work was to investigate the utility of menu systems to complex software tools by building a user interface to SOFTLIB. We conclude that menu systems are far from ideal in such situations because of the range of possible options which must be handled by the system.

Abstract This paper describes an electronic mail system which has been implemented to provide facilities for the receiver as well as the sender of electronic mail. As well as the usual mail creation, transmission and filing operations, the system allows the receiver to specify automatic redirection of mail, and provides classification facilities so that the order of mail presentation is under the receiver's control. The system also includes an automatic mechanism for acknowledging mail and for cancelling mail which is either out‐of‐date or which was sent in error. The model on which the system is based is a non‐automated office, so analogues of waste paper baskets, etc. are provided.

Abstract This paper describes a pattern matching system which has been implemented as a set of library procedures. The system provides a concise and consistent method of pattern definition and facilities for defining context sensitive pattern matching, defining repetitive patterns and defining alternatives. The operations available to the user allow him to identify if a substring matches a pattern, to extract that substring, to replace that substring and to associate a name with that substring. The system has applications in information retrieval, text manipulation and language processing.

This paper examines the advantages and disadvantages of teaching machine language programming to computer science undergraduate students. A teaching language based on reverse Polish notation, but with high-level control constructs, is presented as an alternative to conventional assembly language. Experiences with using this language are described.