Report Series 1998 ------------------ All reports are in PDF and postscript format compressed using gzip. Missing reports will be added soon or contact authors directly. Bridging the Gap Between Past and Future in RE: A Scenario-Based Approach (CREWS-98-38.ps) (PDF) Peter Haumer, Patrick Heymans, Matthias Jarke, and Klaus Pohl in Proceedings of the Fourth IEEE International Symposium on Requirements Engineering (RE'99), 7-11 June 1999, University of Limerick, Ireland. Abstract Requirements Engineering (RE) investigates the impact of a future-oriented change vision, but the move towards this vision must consider a context heavily shaped by the past. As RE be-comes a continuous process throughout the system lifecycle, it must achieve an effective combination of envisionment and traceability. In this paper, we describe a scenario-based solution to this problem which is based on an integration of five ingredients: (a) the persistent capture of context in the form of real world scenes captured in multimedia; (b) formal agent-oriented model-ling with a semantics that allows distributed interactive animation; (c) message trace diagrams as a medium for exchanging animation test cases and traces; (d) a goal model to control and record the RE process; and (e) a process-integrated tool environment to ensure method-guidance and traceability with as little effort as possible. In addition to the basics of our approach, we also describe its prototypical implementation in the CREWS-EVE environment and demonstrate its usefulness with examples from a case study in the production industry. Analysing Socio-Technical System Requirements (CREWS-98-37.ps) (PDF) A. G. Sutcliffe and S. Minocha Abstract Few RE methods address analysis of socio-technical system requirements. This paper describes a method for analysing dependencies between computer systems and users/stakeholders in the operational environment. Domain scenarios describing the system and its context are used to create an environment model based on the i* notation. The dependencies between inbound and outbound events between the system and its usage environment are analysed to elicit requirements to process system input or generate system output. Coupling metrics are applied to these events to assess the degree of dependencies between the system and the users. High level requirements are suggested to deal with different types of organisational design. The method is illustrated with a case study of a service engineer support system. Human Errors and System Requirements (CREWS-98-36.ps) (PDF) A. G. Sutcliffe, J. Galliers and S. Minocha in Fourth IEEE International Symposium on Requirements Engineering (RE'99) Abstract This paper reports a method of assessing the implications for human error on system requirements, a topic not usually considered during requirements engineering (RE).. In our previous work, we proposed a taxonomy of influencing factors that might contribu te to human error. This paper takes the taxonomy and elaborates it to suggest generic requirements to deal with problems in different layers of the taxonomy. Components of the taxonomy are combined into a causal model for error, represented as a Bayesian Belief Net (BBN). BBNs model the error influences arising from user knowledge, ability, and the task environment. These are combined with factors describing the complexity of action and user interface quality in scenarios of projected system usage. The BB N model predicts probabilities of slips and mistakes. These are assessed according to action types in the scenario to suggest generic requirements to prevent the error or to deal with its consequences. The method is illustrated by a service engineer suppo rt system application. Linking Business Modelling to Socio-techincal System Design (CREWS-98-35.ps) (PDF) A. G. Sutcliffe and S. Minocha in Proceedings of the 11th Conference on Advanced Information Systems Engineering, CAiSE'99, Heidelberg, Germany, June 14-18, 1999. Abstract Few methods address analysis of socio-technical system requirements. This paper describes a method for analysing dependencies between computer systems and users/stakeholders in the operational environment. Domain scenarios describing the system and its co ntext are used to create an environment model based on the i* notation. A method is proposed to define business organisational relationships, according to the coupling between agents determined by types of event flows between them, and secondly, by operat ionalising transaction cost theory to obtain an a priori view of relationships according to the market context for a client and supplier. Coupling metrics are applied to assess the degree of dependencies between the system and the users. High-level requir ements are suggested to deal with different types of organisational design. The method is illustrated with a case study of a service engineer support system. A Causal Model of Human Error for Safety-Critical User Interface Design (CREWS-98-34.ps) (PDF) Julia Galliers, Shailey Minocha and Alistair Sutcliffe submitted to Special Issue on 'User Interface Design for safety-Critical Systems' of the Journal of Transactions of Computer Human Interaction (TOCHI) - currently under review Abstract This paper describes a method of assessing the implications for human error on user interface design of safety-critical software. In previous work we have proposed taxonomy of influencing factors that contribute to error. In this paper, components of the taxonomy are combined into a mathematical and causal model for error, represented as a Bayesian Belief Net (BBN). The BBN quantifies error influences arising from user knowledge, ability and the task environment, combined with factors describing the compl exity of user action and user interface quality. The BBN model predicts probabilities of different types of error, slips and mistakes, for each component action of a task involving user-system interaction. We propose an Impact Analysis Method that involve s running test scenarios against this causal model of error in order to determine those user actions that are prone to different types of error. Applying the proposed method will enable the designer to determine the combinations of influencing factors an d their interactions that are most likely to influence human error. Finally we show how such scenario-based causal analysis can be useful as a means of focusing on specifically relevant guidelines for safe user interface (UI) design. In the paper the prop osed method is demonstrated through a case study of an operator performing a task using the control system for a laser spectrophotometer. Guiding Requirement Engineering with a Process Map (CREWS-98-33.ps) (PDF) Mustapha Tawbi, Carine Souveyet appeared in Proceedings of MFPE'99: Second International Workshop on The Many Facets of Process Engineering - From Theory to Practice, Tunis, Tunisia, 12-14 May 1999. Abstract The approach CREWS-L'Ecritoire developed within the CREWS project tightly couples goal modelling and scenario authoring to elicit system requirements. The paper focuses on the process aspect of the approach. It presents the process model as composed of a map and associated guidelines. The map is a directed graph of intentions and strategies to flow from one intention to another. Intention achievement is supported by guidelines. The process model and its enactment mechanism have been implemented in a software tool called l'ECRITOIRE. The paper presents the process map of the approach CREWS-l'ECRITOIRE and illustrates its use with an example to elicit the requirements of a system to recycle objects. Experience With Goal-Scenario Coupling in Requirements Engineering (CREWS-98-32.ps) (PDF) C. Rolland, G. Grosz, R. Kla In Proceedings of the Fourth IEEE International Symposium on Requirements Engineering (RE'99), 7-11 June 1999, University of Limerick, Ireland. Abstract In the context of Requirements Engineering (RE), both goal-driven approaches and scenario-based approaches have proven useful for eliciting, justifying and validating system requirements. In order to overcome some of the deficiencies and limitations of these approaches when used in isolation, proposals have been made to couple goals and scenarios together. The CREWS -L'Ecritoire approach advocates for a bi-directional coupling allowing movement from goals and scenarios and vice-versa. The paper reports on an experimentation of the CREWS-L'Ecritoire approach on a large scale business process re-engineering project conducted in the context of an electricity supply and distribution company. The focus is on a set of issues that we found important and that we believe are not specific to our approach. We considered three kinds of issues, those which are found in goal-driven approaches, those in scenario-based approaches, and those specific to goal-scenario coupling. In this paper, we devote a specific attention to the third kind of issues and assess the extent to which the goal-scenario coupling helps to resolve the first two kinds of issues. Guiding Use Case Authoring: Results of an Empirical Study (CREWS-98-31.ps) (PDF) C. Ben Achour, C. Rolland, N.A.M. Maiden, C. Souveyet in Proceedings of the Fourth IEEE International Symposium on Requirements Engineering (RE'99), 7-11 June 1999, University of Limerick, Ireland Abstract This paper presents results from the first of two empirical studies which examine the effectiveness of guidelines for use case authoring. The ESPRIT 21.903 CREWS long-term research project has developed style and content guidelines for authoring use cases for requirements acquisition and validation. The effectiveness of these guidelines has been evaluated under different conditions. Results indicate that: i. the authoring guidelines improve the overall quality of the use case prose, ii the different guidelines work differently and with different levels of efficiency, and iii use cases are never entirely correctly written; thus, they can be systematically corrected. The paper details a qualitative and quantitative comparison between guided and non-guided use case authoring. It outlines lessons learned and implications for the CREWS software tools design. Scenario-Based Techniques for Supporting the Elaboration and the Validation of Formal Requirements (CREWS-98-30.ps) (PDF) Patrick Heymans and Eric Dubois appeared in Requirements Engineering Journal, Vol. 3, No. 3-4, 1998. Abstract Developing complex, safety critical systems requires precise, unambiguous specification of requirements. A formal specification language is thus well suited to this task. Formal specification languages require, but also exacerbate, the need for tools. In particular, tools should support the elaboration (how to build the formal specification?) and the validation (how to check the adequacy of the specification towards the informal needs of the various stakeholders?). This paper focuses on the language Albert II, a formal language designed for the purpose of ex-pressing requirements for distributed real-time systems. It presents two contributions supporting its use. The first contribution aims at improving the elaboration process by providing a method for constructing an Albert II description from scenarios expressing the stakeholders' requirements. These are represented through Message Sequence Charts extended to deal with composite systems. The second contribution takes the form of a requirements validation tool (a so-called animator) that the stakeholders can use interactively and cooperatively in order to explore different possible behaviours (or instance-level scenarios) of the future system. These behaviours are automatically checked against the formal requirements specification. CREWS Validation Frames: Patterns for Validating Systems Requirements (CREWS-98-29.ps) (PDF) N.A.M. Maiden, M. Cisse, H. Perez, D. Manuel appeared in Fourth International Workshop on Requirements Engineering: Foundation for Software Quality (RESFQ), Pisa, Italy, June 8th-9th, 1998. Abstract This paper proposes a pattern language for socio-technical system design to inform validation of system requirements. The development of this language takes inspiration from Alexander's pattern language for building design in architecture. It identifies different types of patterns which fulfil different roles in the requirements engineering process. This pattern-based validation approach has been operationalised in the CREWS-SAVRE software prototype. CREWS-SAVRE applies patterns to both scenarios and requirements documents to detect missing and incorrect system requirements, as well as to recommend new requirements which can improve the design of the socio-technical system. An Integration of Scenario-Based Requirements Elicitation and Validation Techniques. (CREWS-98-28.ps) (PDF) Peter Haumer, Patrick Heymans, Klaus Pohl Abstract Scenarios are widely used in industry to support requirements elicitation and validation. Tool support is a prerequisite for effective use and management of scenarios. In this paper we propose to integrate two scenario-based techniques developed in the ESPRIT Project CREWS. One supports the elicitation of a goal model from real-world scenarios. The other allows to validate a formal system specification by playing instance-level scenarios against it. Interestingly, the two of them complement each other in various respects. We outline the benefits obtained by integration and present how we performed it at the conceptual and technical levels. The resulting integrated environment has been validated on a small case study in the manufacturing domain. Guiding Goal Modelling Using Scenarios. (CREWS-98-27.ps) (PDF) C. Rolland, C. Souveyet, C. Ben Achour. appeared in IEEE Transactions on Software Engineering: Special Issue on Scenario Management, Vol. 24, No. 12, 1998. Abstract Even though goal modelling is an effective approach to requirements engineering, it is known to present a number of difficulties in practice. The paper discusses these difficulties and proposes to couple goal modelling and scenario authoring to overcome them. Whereas existing techniques use scenarios to concretise goals, we use them to discover goals. Our proposal is to define enactable rules which form the basis of a software environment to guide the requirements elicitation process through interleaved goal modelling and scenario authoring. The focus of the paper is on the discovery of goals from scenarios. The discovery process is centred around the notion of a Requirement Chunk (RC) which is a pair . RCs enter into AND, OR and Refinement relationships with each other. The enactable rules support the discovery of RCs and of their inter-relationships.The result is an easy to use, flexible, scaleable and automated support for requirements elicitation that produces benefits outside requirements gathering : system requirements are tracked from business goals, alternative design options are explicitly discussed and tracked, requirements are expressed and concretised through scenarios at different levels of abstraction. The approach presented in the paper is illustrated with the ATM example. Writing and Correcting Textual Scenarios for System Design (CREWS-98-26.ps) (PDF) Camille Ben Achour appeared in the Proceedings of the Natural Language and Information Systems (NLIS'98) Workshop 28th August 1998, Vienna, Austria, 1998. Abstract Since a few years, scenarios have gained in popularity in Requirements Engineering. Textual scenarios are narrative descriptions of flows of actions between agents. They are often proposed to elicit, validate or document requirements. The CREWS experience has shown that the advantage of scenarios is their easiness of use, and that their disadvantage stands in the lack of guidelines for 'quality' authoring. In this article, we propose guidance for the authoring of scenarios. The guided scenario authoring process is divided into two main stages: the writing of scenarios, and the correcting of scenarios. To guide the writing of scenarios, we provide style and contents guidelines referring to a conceptual and a linguistic model of scenarios. Our assumption is that scenarios written in conformance to these guidelines can be semi-automatically analysed. Else, to guide the correcting of scenarios, we propose a set of enactable rules. These rules aim at the clarification, completion and conceptualisation of scenarios, and help the scenario author to improve his scenarios until acceptable quality in the terms of the former scenario models. Main Concepts for Cooperative Work Place Analysis. (CREWS-98-25.ps) (PDF) S. Nurcan. appeared in Telecooperation Conference of the 15th IFIP World Computer Congress 1998, 31 August-4 September 1998, Vienna, Austria, 1998. Abstract Computer Supported Cooperative Work (CSCW) studies the possibilities and effects of technological support for agents involved in cooperative work processes. Many technologies dedicated to cooperative work environments such us cooperative requirements engineering or cooperative information systems have emerged in the past decade. For many organisations, structured and unstructured cooperative activities coexist in work processes and must be managed in the final solution. It is necessary to emphasise the specificities of these processes in order to take them into account as soon as possible during design. This work presents a model which is a synthesis of the concepts we believe essential for cooperative work place analysis. A Proposal for Improving the Quality of the Organisation of Scenario Collections. (CREWS-98-24.ps) (PDF) C. Ben Achour, C. Rolland, C. Souveyet. appeared in Proceedings of the REFSQ'98 Workshop on requirements engineering foudnation for software quality, Pisa, June 1998. Abstract The study and practice of scenarios raise the question of managing the combinatorial explosion of the number of scenarios. This article proposes a set of relationships to organise a collection of scenarios. Three types of relationships are proposed : OR, AND, and Refinement. These relationships are generic and can be used to manage any kind of scenarios. Using them leads to build a structured network of scenarios. In addition, to guide the construction of 'quality' networks of scenarios, the paper presents quality properties and heuristic guidelines. The approach is illustrated by the CREWS approach. L'ECRITOIRE a tool to support a goal-scenario based approach to requirements engineering. (CREWS-98-23.ps) (PDF) M. Tawbi, C. Souveyet, C. Rolland. submitted to the Information Software and Technology Journal. Abstract The paper presents 'L'ECRITOIRE' a tool which supports the goal-scenario based approach for requirements engineering developed within the CREWS project. The approach tightly couples goal modeling and scenario authoring to elicit system requirements The approach is supported by guidelines encapsulated in modular method chunks that are assembled in different ways called method paths. A method path is a situated 'good practice' of goal modeling and scenario authoring. The paper presents one of the CREWS_l'ECRITOIRE method paths and illustrates it use through a l'ECRITOIRE session. A Reuse-Oriented Approach for the Construction of Scenario Based Methods. (CREWS-98-22.ps) (PDF) V. Plihon, J. Ralyté, A. Benjamen, N.A.M. Maiden, A. Sutcliffe, E. Dubois, P. Heymans. appeared in Proceedings of the International Software Process Association's 5th International Conference on Software Process (ICSP'98), Chicago, Illinois, USA, 14-17 June 1998. Abstract Despite the recent interest in scenarios, the development of new methods and tools for Requirements Engineering integrating scenario based approaches has been limited. This paper reports on four different processes developed from research undertaken as part of the CREWS project which the authors believe will improve scenario use and make it more systematic. Furthermore CREWS aims to integrate these approaches into a method for scenario-based requirements engineering. To achieve this objective and be able to include existing approaches such as use case analysis we develop a component based approach which reflects a shift towards a reuse-centric approach to method engineering. The paper presents CREWS method and meta-method knowledge through the implementation of an SGML database to store, retrieve and dynamically compose chunks of CREWS processes. Are Methods Really Useful ? (CREWS-98-21.ps) (PDF) C. Rolland. appeared in Proceedings of the 20th International Conference on Software Engineering ICSE'98, Kyoto, Japan, April 1998. No abstract. Formalising Guidance for the CREWS Goal-Scenario Approach to Requirements Engineering. (CREWS-98-20.ps) (PDF) S. Si Saïd, C. Rolland. appeared in Proceedings of the Eight European - Japanese Conference on Information Modelling and Knowledge Bases. May 25-29, Vamala, Finland, 1998. Abstract Guidance plays a crucial role in requirements engineering (RE) as this task is both ill defined and highly intellectual. The guidance approach presented in this paper consists of supporting requirements engineers by a collection of enactable guidelines embodied in a computer environment. The key characteristics of the approach is its intention orientation. Guidance can be provided once the intention to be achieved has been elicited. Two kinds of guidance are proposed, step and flow guidance. The former supports the fulfilment of intentions whereas the latter helps in intention elicitation. The paper presents the two types of guidance, the corresponding guidelines and the Computer Aided Requirements Engineering (CARE) environment which supports their enactment. The approach is illustrated with the CREWS requirements engineering approach which elicits requirements through interleaved goal modelling and scenario authoring. Process Centred Approach for Developing Tool Support of Situated Methods. (CREWS-98-19.ps) (PDF) C. Souveyet, M. Tawbi. appeared in Proceedings of the 9th International DEXA Conference on Database and Expert Systems Applications, Vienna, Austria, August 1998. Abstract A reuse based approach to construct software tool supporting a specific method built "on the fly" is presented in this paper. Its originality is to apply a process view on the reusable component which is either method chunk or software chunk. Our process view leads to construct method and software tool by assembling chunks. Chunks which are either method or software ones can be assembled in different ways depending on the situation of the project at hand. One of these ways is called a method or a software path. Our aim is to support the construction of a specific method path and its use in a CASE environment. The paper focuses on (i) the description of a process centred approach for software tool development (ii) its use in the development of the tool "l'écritoire" and (iii) the support of software engineer through a set of guidelines. A Comprehensive View of Process Engineering. (CREWS-98-18.ps) (PDF) C. Rolland. appeard in Proceedings of the 10th International Conference CAiSE'98, B. Lecture Notes in Computer Science 1413, Pernici, C. Thanos (Eds), Springer. Pisa, Italy, June 1998. Abstract The paper proposes a faceted framework to understand and classify issues in system development process engineering. The framework identifies four different but complementary view-points. Each view allows us to capture a particular aspect of process engineering. Inter-relationships between these aspects allow us to show the influence that one aspect has on another. In order to study, understand and classify a particular aspect of process engineering in its diversity we associate a set of facets with each aspect. The paper uses the framework to raise questions, problems and research issues in the field. Improving Reviews by Extended Traceability. (CREWS-98-17.ps) (PDF) Peter Haumer, Klaus Pohl, Klaus Weidenhaupt, Matthias Jarke appeared in Scenario-Based System Development (A mini-track within the Emerging Technologies Track of the Thirty-Second Annual Hawaii Inter-national Conference on Systems Sciences (HICSS-32), Maui, HI, January 5-8, 1999. Abstract When defining a new system, the history and functionality of the system to be replaced should be considered. Thereby making the same failure twice or neglecting important system functionality can be avoided. The requirements of the existing system are typically elicited by analysing concrete system usage scenarios. The requirements are typically being represented using con-ceptual models. To establish conceptual models of high quality, reviewing the models is common practice. The problem faced with when reviewing conceptual models, is that the reviewer can not assess and therefore understand the basis (concrete system usage) on which the conceptual models where build. In this paper, we present an approach to overcome this problem. We argue to establish extended traceability, by recording concrete system usage scenarios using rich media (e.g. video, speech, graphic) and interrelating the recorded observations with the con-ceptual models. We discuss the principle improvements for reviewing processes result-ing from the extended traceability and illustrate the advantages with excerpts of the case study performed in a mechanical engineering company. Requirements Elicitation and Validation with Real World Scenes. (CREWS-98-16.ps) (PDF) Peter Haumer, Klaus Pohl, Klaus Weidenhaupt appeared in IEEE Transactions on Software Engineering, Vol. 24, No. 12, Special Issue on Scenario Management, December 1998. Abstract Scenarios are an excellent means for eliciting and validating requirements. In contrast to a requirements specification which defines the requirements for the future system at a con-ceptual level (i.e. class or type level), a scenario represents a concrete example of current or future system usage. In early RE phases, scenarios are used to support the definition of the main goals (high level requirements) to be achieved by the new system. In many cases, most of those goals can be elicited by observing, documenting and analysing scenarios about current system usage, i.e. the new system must often fulfil most of the functional and non-functional goals of the existing system. To support the elicitation and validation of the goals achieved by the existing system we propose to capture current system usage using rich media (e.g. video, speech, pictures etc.) and to interrelate those observations with the goal definitions. More precisely, we propose to relate the parts of the observations which have caused the definition of a goal or against which a goal was validated with the corresponding goal(s). Thereby a fine-grained interre-lation between the conceptual goal model and the recorded observations is established. These interrelations provide the basis for explaining and illustrating a goal model to, e.g., untrained stakeholders and/or new team members, and thereby improving a common understanding of the goal model; detecting, analysing and resolving a different interpretation of the observations; comparing different observations using computed goal annotations based on the inter-relations; refining or detailing a goal model during later process phases. From Early to Late Formal Requirements: A Process-Control Case Study. (CREWS-98-15.ps) (PDF) Eric Dubois, Eric Yu, Michael Petit. to appear in Proc. of IWSSD9, Isobe, Japan. April 1998. Abstract In this paper, we consider three distinct and connected modelling activities at the Requirements Engineering (RE) level. Within the context of reactive systems, we suggest how these three activities can be supported by the use of appropriate formal languages, namely Kaos, Albert and Timed Automata. The i* framework is used for linking the various formal models and for providing a "high level'' model in terms of which organizational issues are captured. A small process control example is used to illustrate the proposed approach. Layered Components. (CREWS-98-14.ps) (PDF) Luc Claes appeared in Component-based Information Systems Engineering Workshop (CAiSE'98), Pisa, June 1998. Abstract We describe a generic software environment intended to assist the construction of applications by the composition of reusable components. Two classes of components (and their related systems) are clearly distinguished: operational components (or components in the 'classical', technological sense) and descriptive components, encapsulating meta-data about, amongst others, their operational counterparts. Components are viewed as actors in a communicating entities system. Communications capabilities and needs are abstracted as a set of layers, each layer denoting a delimited conventions set and satisfying or dictating functional requirements. A case study describes how we are using - or intend to use - our models in real life applications. The selected case consists in the interconnection of two, otherwise incompatible, CASE tools. Abstraction Guides: Interrelating Conceptual Models with Real World Scenes (CREWS-98-13.ps) (PDF) P. Haumer, K. Pohl, K. Weidenhaupt appeared in Fourth International Workshop on Requirements Engineering: Foundation for Software Quality (RESFQ), Pisa, Italy, June 8th-9th, 1998. Abstract The role of the requirements engineer is to establish a complete consistent and unambiguous requirements specification which defines the requirements at a conceptual level. Many traditional modelling approaches from Structured Analysis, to UML-based methods supporting him in this task neglect the use of concrete examples about current or future system usage. In this paper, we present so called Abstraction Guides which assist the requirements engineer in establishing and applying an interrelating structure between conceptual models and persistent recorded usages of existing systems called Real World Scenes (RWS). This structure is used to improve traceability, understandability and negotiation of conceptual models. We show how Abstraction Guides define support for eliciting requirements from RWS, vali-dating requirements against RWS, explanation of conceptual models, and comparing scenes and models. Guiding Scenario Authoring (CREWS-98-12.ps) (PDF) C. Ben Achour appeared in Proceedings of the Eighth European - Japanese Conference on Information Modelling and Knowledge Bases. May 25-29, Vamala, Finland. Abstract Since a few years, scenario based requirements engineering approaches have gained in popularity. Textual scenarios are narrative descriptions of flows of actions between agents. They are often proposed to elicit, validate or document requirements. The CREWS experience has shown that the advantage of scenarios is their easiness of use, and that their disadvantage stands in the lack of guidelines for authoring. In this article, we propose guidance for the authoring of scenarios. The guided scenario authoring process is divided into two main stages : the writing of scenarios, and the correcting of scenarios. To guide the writing of scenarios, we provide style and contents guidelines referring to a conceptual and a linguistic model of scenarios. To guide the correcting of scenarios, we propose a set of enactable rules. These rules aim at the clarification, completion and conceptualisation of scenarios, and help the scenario author to improve his scenarios until acceptable quality in the terms of the former scenario models. The paper presents both style / contents guidelines, and correction rules, and illustrates them with the London Ambulance Service example. CASE Environment Adaptability: Bridging the Islands of Automation (CREWS-98-11.ps) (PDF) K. Lyytinen, P. Martiin, J.-P. Tolvanen, M. Jarke, K. Pohl, K. Weidenhaupt appeared in Proceedings of the Eight annual Workshop on Information Technologies and Systems WITS'98. Computer Science and Information Systems Reports TR-19, University of Jyväskylä, Finnland. Abstract In current CASE environments a user has to choose between efficient computerized sup-port using a fixed methodical framework which may not fit his situation, or the freedom to do what seems appropriate in the given circumstance, but at the cost of losing efficient technological support. In this paper we examine adaptable metamodel based environments as a means to resolve this dilemma. Metamodel based environments provide means to rep-resent and modify knowledge about development products, processes, and representation schemes to improve the designer-task fit. Metamodel based adaptability is not a new inno-vation. Yet, earlier metamodel based approaches have tended to create islands of automa-tion that focus on improving adaptability either in ontologies, notations, or process defini-tions. The paper applies a framework which integrates these aspects and thereby increases environment adaptability that covers a wider spectrum of development situations. The metalevel based integration is demonstrated by describing how two metamodel based tools focusing on different aspects of adaptability can be integrated. The resulting integrated environment encompasses both product (ontology/notation) and process aspects. A Filter-Mechanism for Method-Driven Trace Capture (CREWS-98-10.ps) (PDF) R. Dömges, K. Pohl, K. Schreck appeard in CAiSE’98 Conference on Advanced Information Systems Engineering, June, 1998 Abstract Traceability is a prerequisite for developing high quality (software) systems. Recording and maintaining all available information is too labour intensive and thus by far too expensive. A project-specific definition of the trace information to be recorded and the method fragments (so called trace fragments) to be executed for recording the information provides a solution for this problem. But the amount of traces to be recorded does not only vary from project to project. It also varies between project phases and even within a project phase. As a consequence project-specific trace fragments need to be adapted according to the actual project phase. In this paper we propose a model-based filter mechanism to significantly reduce the required effort to adapt trace fragments. By defining appropriate filters the project manager is able to (dynamically) adapt the project-specific trace fragments to the actual needs. We present an example to highlight the benefits of the approach and discuss possible extensions. PRIME: Towards Process-Integrated Environments (CREWS-98-09.ps) (PDF) K. Pohl, K. Weidenhaupt, R. Dömges, P. Haumer, M. Jarke, R. Klamma accepted for ACM Transactions on Software Engineering and Methodology, 1999. Abstract Research in process-centered environments (PCEs) has focused on project management support and has neglected method guidance for the engineers performing the (software) engineering process. It has been dominated by the search for suitable process modeling languages and enactment mechanisms. The consequences of the process orientation on the computer-based engineering environments, i.e. the interactive tools used during process performance, have been studied much less. In this paper, we present the PRIME (PRocess-Integrated Modeling Environments) framework which empowers method guidance through process-integrated tools. In contrast to the tools of PCEs, the process-integrated tools of PRIME adjust their behavior according to the current process situation and the method definitions. Process-integration of PRIME tools is achieved through the definition of tool models; the integration of the tool models and the method definitions; the interpretation of the integrated environment model by the tools, the process-aware control integration mechanism, and the enactment mechanism; the synchronization of the tools and the enactment mechanism based on a comprehensive interaction protocol. We sketch the implementation of PRIME as reusable implementation framework which facilitates the realization of process-integrated tools as well as the process-integration of legacy tools. We define a six-step procedure for building a PRIME-based process-integrated environment (PIE) and illustrate how PRIME facilitates change integration on an easy-to-adapt modeling level. Following the six-step procedure we have implemented two process-integrated environments (PRIME-CREWS and TECHMOD) which have been applied in small case studies. Supporting Scenario-based Requirements Engineering (CREWS-98-08.ps) (PDF) A.G. Sutcliffe, N.A.M. Maiden, S. Minocha, D. Manuel appeared in IEEE Transactions on Software Engineering: Special Issue on Scenario Management, Vol. 24, No. 12, 1998. Abstract Scenarios have been advocated as a means of improving requirements engineering yet few methods or tools exist to support scenario based RE. The paper reports a method and software assistant tool for scenario-based RE that integrates with use case approaches to object oriented development. The method and operation of the tool are illustrated with a financial system case study. Scenarios are used to represent paths of possible behaviour through a use case and these are investigated to elaborate requirements. The method commences by acquisition and modelling of a use case. The use case is then compared with a library of abstract models that represent different application classes. Each model is associated with a set of generic requirements for its class, hence, by identifying the class(es) to which the use case belongs, generic requirements can be reused. Scenario paths are automatically generated from use cases, then exception types are applied to normal event sequences to suggest possible abnormal events resulting from human error. Generic requirements are also attached to exceptions to suggest possible ways of dealing with human error and other types of system failure. Scenarios are validated by rule-based frames which detect problematic event patterns. The tool suggests appropriate generic requirements to deal with the problems encountered. The paper concludes with a review of related work and a discussion of the prospects for scenario based RE methods and tools. Scenario-based Requirements Analysis (CREWS-98-07.ps) (PDF) A.G. Sutcliffe accepted for publication in the Requirements Journal, 1998 Abstract A method for scenario based requirements engineering is described. The method uses two types of scenario,structure models of the system context and scripts of system usage. Amodelling language is reported for describing scenarios, and heuristics aregiven to cross check dependencies between scenario models and the requirements specification. Heuristics aregrouped into several analytic treatments that investigate correspondencesbetween users' goals and system functions; input events and systemprocesses to deal with them; system outputand its destination in the scenario model, and acceptability analysis ofsystem output for different stakeholders. The method is illustrated with acase study taken from the London Ambulance Service report. The prospectsfor scenario based RE and relatedwork are discussed. Tracing Requirements Errors to Problems in the Requirements Engineering Process (CREWS-98-06.ps) (PDF) A.G. Sutcliffe, A. Economou, P. Markis accepted for publication in the Requirements Engineering Journal, 1998. Abstract A case study of requirements engineering practice is reported. The application, a decision support system for the Greek Ministry of Health, was investigated by studying the process of requirements analysis through to design and implementation. A usability analysis was then conducted on the designed system with the users. Several usability problems were discovered, and interviews uncovered further problems with the system that could be attributed to failure in requirements engineering. Even though requirements were explicitly stated and the system was an evolution from an existing legacy system, functionality was defective and usability was poor. The client's prime concern for redeveloping the system was to improve usability; unfortunately communications problems in the RE process meant that the developers did not appreciate this. The implications for RE methods and understanding the RE process are discussed. Specifying the reuse context of Scenario Method Chunks (CREWS-98-05.ps) (PDF) C. Rolland, V. Plihon, Y. Ralyté appeared in Proceedings of the 10th International Conference CAiSE'98, B. Lecture Notes in Computer Science 1413, Pernici, C. Thanos (Eds), Springer, pp. 191. Pisa, Italy, June 1998. Abstract There has been considerable recent interest in scenarios for accompanying many of the various activities occurring in the development life cycle of computer based systems. Besides the integration of scenarios in methods such as Objectory and software tools such as Rationale Rose has proven useful and successful. Consequently, there is a demand for adapting existing methods to support specific design activities using scenario based approaches. The view developed in this paper is that scenario based approaches should be looked upon as reusable components. Our concern is therefore twofold : first, to represent scenario based approaches in a modular way which eases their reusability and second, to specify the design context in which these approaches can be reused in order to facilitate their integration in existing methods. The paper concentrates on these two aspects, presents an implementation of our proposal using SGML to store available scenario based approaches in a multimedia hypertext document and illustrates the retrieval of components meeting the requirements of the user by the means of SgmlQL queries. Describing business processes with a guided use case approach (CREWS-98-04.ps) (PDF) S. Nurcan, G. Grosz, C. Souveyet appeared in Proceedings of the 10th International Conference CAiSE'98, B. Lecture Notes in Computer Science 1413, Pernici, C. Thanos (Eds), Springer, pp. 339-362. Pisa, Italy, June 1998. Abstract Business Process (BP) improvement and alike require accurate descriptions of the BPs. We suggest to describe BPs as use case specifications. A use case specification comprises a description of the context of the BP, the interactions between the agents involved in the BP, the interactions of these agents with an automated system supporting the BP and attached system internal requirements. Constructing such specifications remains a difficult task. Our proposal is to use textual scenarios as inputs, describing fragments of the BP, and to guide, using a set of rules, their incremental production and integration in a use case specification also presented in a textual form. The paper presents the structure of a use case, the linguistic approach adopted for textual scenarios analysis and the guided process for constructing use case specifications from scenarios along with the guidelines and support rules grounding the process. The process is illustrated with a real case study borrowed to an Electricity Company. CREWS-SAVRE: Scenarios for Acquiring and Validating Requirements (CREWS-98-03.ps) (PDF) N.A.M. Maiden accepted for Journal of Automated Software Engineering, 1998. Abstract This paper reports research into semi-automatic generation of scenarios for validating system requirements. The research was undertaken as part of the ESPRIT IV 21903 'CREWS' long-term research project. The paper presents the underlying theoretical models of domain knowledge, computational mechanisms and user-driven dialogues needed for scenario generation. It describes how CREWS draws on theoretical results from the ESPRIT III 6353 'NATURE'basic research action, that is object system models which are abstractions of the fundamental features of different categories of problem domain. CREWS uses these models to generate normal course scenarios, then draws on theoretical and empirical research from cognitive science, human-computer interaction, collaborative systems and software engineering to generate alternative courses for these scenarios. The paper describes a computational mechanism for deriving use cases from object system models, simple rules for use case composition, taxonomies of classes of exceptions which give rise to alternative courses in scenarios, and a computational mechanism for generation of multiple scenarios from use case specifications. Scenario-based Analysis of Non-Functional Requirements (CREWS-98-02.ps) (PDF) Alistair G. Sutcliffe and Shailey Minocha appeared in Fourth International Workshop on Requirements Engineering: Foundation for Software Quality (RESFQ), Pisa, Italy, June 8th-9th, 1998. Abstract Scenarios have been advocated as an effective means of acquiring and validating requirements as they capture examples and real world experiences that users can understand [Potts et al. 1994]. Although scenarios have appeared in many diverse forms [Carroll 1995], most authors have used them for behavioural analysis, e.g. scenario scripts [Potts et al. 1994] and use case scenarios [Jacobson et al. 1992, Graham 1996, Cockburn 1995]. More wider ranging views of scenarios as context settings for understanding socio-technical systems have been proposed by Eason et al. [Eason et al. 1996] and Kyng [Kyng 1995], but these too focus on user activity and system functionality, rather than system qualities also generally referred to as non-functional requirements. This paper explores the role scenarios could play in addressing non-functional requirements and proposes a method for scenario generation and analysis for the purpose. Guiding the construction of textual use case specifications (CREWS-98-01.ps) (PDF) Colette Rolland, Camille Ben Achour appeared in Data & Knowledge Engineering Journal, Vol 25, N°1-2, pp. 125-160, (ed. P. Chen, R.P. van de Riet), North Holland, Elsevier Science Publishers. March 1998. Abstract An approach for guiding the construction of use case specifications is presented. A use case specification comprises contextual information of the use case, its change history, the complete graph of possible pathways, attached requirements and open issues. The proposed approach delivers a use case specification as an unambiguous natural language text. This is done by a stepwise and guided process which progressively transforms initial and partial natural language descriptions of scenarios into well structured, integrated use case specifications. The basis of the approach is a set of linguistic patterns and linguistic structures. The former constitutes the deep structure of the use case specification whereas the latter corresponds to the surface structures. The paper presents the use case model, the linguistic basis and the guided process along with the associated guidelines and support rules. The process is illustrated with the automated teller machine (ATM) case study. Send questions and comments to crewsrep@informatik.rwth-aachen.de