Jolita Ralyté

A proposal for a scenario classification framework

The requirements engineering, information systems and software engineering communities recently advocated scenario-based approaches which emphasise the user/system interaction perspective in developing computer systems. Use of examples, scenes, narrative descriptions of contexts, mock-ups and prototypes-all these ideas can be called scenario-based approaches, although exact definitions are not easy beyond stating that these approaches emphasise some description of the real world. Experience seems to tell us that people react to ‘real things’ and that this helps in clarifying requirements. Indeed, the widespread acceptance of prototyping in system development points to the effectiveness of scenario-based approaches. However, we have little understanding about how scenarios should be constructed, little hard evidence about their effectiveness and even less idea about why they work.The paper is an attempt to explore some of the issues underlying scenario-based approaches in requirements engineering and to propose a framework for their classification. The framework is a four-dimensional framework which advocates that a scenario-based approach can be well defined by itsform, content, purpose andlife cycle. Every dimension is itself multifaceted and a metric is associated with each facet. Motivations for developing the framework are threefold: (a) to help in understanding and clarifying existing scenario-based approaches; (b) to situate the industrial practice of scenarios; and (c) to assist researchers develop more innovative scenario-based approaches.

Towards a generic model for situational method engineering

The work presented in this paper is related to the area of Situational Method Engineering (SME) which focuses on project-specific method construction. We propose a generic process model supporting the integration of different existing SME approaches. This model shall help the method engineer either selecting one SME approach or combining several approaches that best fit the situation of the method engineering project at hand. The generic model presented in this paper already contains three SME techniques: (1) to assemble method chunks (2) to extend an existing method and (3) to generate a method by abstraction/instantiation of a model/meta-model. The paper presents and illustrates these three techniques and show how other SME techniques could be integrated in the model.

An Assembly Process Model for Method Engineering

The need for a better productivity of system engineering teams, as well as a better quality of products motivates the development of solutions to adapt methods to the project situation at hand. This is known as situational method engineering. In this paper we propose a generic process model to support the construction of a new method by assembling method chunks generated from different methods that are stored in a method base. The emphasis is on the guidance provided by the process model, as well as on the means underlying guidelines such as similarity measures and assembly operators. The process model is exemplified with a case study.

Situational method engineering: combining assembly-based and roadmap-driven approaches

Because the engineering situation of each information system development (ISD) project is different, engineering methods need to be adapted, transformed or enhanced to satisfy the specific project situation. Contributions, in the field of situational method engineering (SME), aim at providing techniques and tools allowing to construct project-specific methods instead of looking for universally applicable ones. In addition to the engineering method tailoring, necessary to fit the project situation, a customization of the engineering method for each engineer participating in the project is also required. Such a configuration allows a better understanding of the method by focusing on guidelines related to the project engineer’s daily tasks. It also increases his/her involvement in the ISD method realization. To achieve this twofold objective (ISD method tailoring and customization), we propose a framework for SME combining an assembly-based approach for project-specific method construction and a roadmap-driven approach for engineer-specific method configuration. The first step of our process provides support to build a new method that is most suitable for the current ISD project situation, whereas the second step aims at choosing the most adapted path (roadmap) to satisfy the requirements of a particular project engineer within the project-specific method. The two core elements of our SME framework are the method chunks repository and the reuse frame. The former concerns reusable method components definition and storage whereas the latter deals with the characterization of the project situation and the project engineer’s profile. In this paper we start first by presenting our SME framework and its core elements: the method chunk repository and the reuse frame. Then we show how to take advantage of them through our two-step process combining assembly-based method construction and roadmap-driven method configuration.

Specifying the Reuse Context of Scenario Method Chunks

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.

A knowledge-based approach to manage information systems interoperability

Interoperability is a key property of enterprise applications, which is hard to achieve due to the large number of interoperating components and semantic heterogeneity. The inherent complexity of interoperability problems implies that there exists no silver bullet to solve them. Rather, the knowledge about how to solve wicked interoperability problems is hidden in the application cases that expose those problems. The paper addresses the question of how to organise and use method knowledge to resolve interoperability problems. We propose the structure of a knowledge-based system that can deliver situation-specific solutions, called method chunks. Situational Method Engineering promotes modularisation and formalisation of method knowledge in the form of reusable method chunks, which can be combined to compose a situation-specific method. The method chunks are stored in a method chunk repository. In order to cater for management and retrieval, we introduce an Interoperability Classification Framework, which is used to classify and tag method chunks and to assess the project situation in which they are to be used. The classification framework incorporates technical as well as business and organisational aspects of interoperability. This is an important feature as interoperability problems typically are multifaceted spanning multiple aspects. We have applied the approach to analyse an industry case from the insurance sector to identify and classify a set of method chunks.

Situational Method Engineering

While previously available methodologies for software like those published in the early days of object technology claimed to be appropriate for every conceivable project, situational method engineering (SME) acknowledges that most projects typically have individual characteristics and situations. Thus, finding the most effective methodology for a particular project needs specific tailoring to that situation. Such a tailored software development methodology needs to take into account all the bits and pieces needed for an organization to develop software, including the software process, the input and output work products, the people involved, the languages used to describe requirements, design, code, and eventually also measures of success or failure. The authors have structured the book into three parts. Part I deals with all the basic concepts, terminology and overall ideas underpinning situational method engineering. As a summary of this part, they present a formal meta-model that enables readers to create their own quality methods and supporting tools. In Part II, they explain how to implement SME in practice, i.e., how to find method components and put them together and how to evaluate the resulting method. For illustration, they also include several industry case studies of customized or constructed processes, highlighting the impact that high-quality engineered methods can have on the success of an industrial software development. Finally, Part III summarizes some of the more recent and forward-looking ideas. This book presents the first summary of the state of the art for SME. For academics, it provides a comprehensive conceptual framework and discusses new research areas. For lecturers, thanks to its step-by-step explanations from basics to the customization and quality assessment of constructed methods, it serves as a solid basis for comprehensive courses on the topic. For industry methodologists, it offers a reference guide on features and technologies to consider when developing in-house software development methods or customising and adopting off-the-shelf ones.

Towards a meta-tool for change-centric Method engineering: A typology of generic operators

The work presented in this paper considers how Method Engineering (ME) helps in method changes that are required by Information Systems (IS) changes. In fact, ME provides different approaches allowing to construct situation- specific methods by adapting, extending, improving existing methods or by assembling method components. All these approaches use a set of operations to realize these method changes. Our objective in this paper is to provide a meta- tool for change-centric ME which takes the form of a typology of generic ME operators. The operators for each specific ME approach are instantiated from the generic ones. The paper illustrates and discusses the instantiation of the generic typology for two assembly-based ME approaches.

Modularization Constructs in Method Engineering: Towards Common Ground?

Although the Method Engineering (ME) research community has reached considerable maturity, it has not yet been able to agree on the granularity and definition of the configurable parts of methods. This state of affairs is causing unnecessary confusion, especially with an ever increasing number of people contributing to ME research. There are several competing notions around, most significantly ‘method fragments’ and ‘method chunks’, but also ‘method components’ and ‘process components’ are used in some quarters and have also been widely published. Sometimes these terms are used interchangeably, but there appears to be important semantic and pragmatic differences. If the differences are unimportant, we should be able to come to an agreement on what construct to promote. Alternatively, the different constructs may serve different purposes and there is a need for them to coexist. If this is the case, it should be possible to pinpoint exactly how they are related and which are useful in what contexts. This panel is a step towards finding common ground in this area, which arguably is at the very core of ME.

Requirements Definition for the Situational Method Engineering

The work presented in this paper is related to the situational method engineering domain, which focus on the project-specific method construction. The techniques proposed by this discipline aim to construct methods by assembling reusable method fragments. The selection of the method fragments is requirements driven. The first step in the situational method engineering consists in analysing the situation of the current project and specifying the requirements for a method supporting this situation. In this paper we propose an approach supporting the definition of the requirements for a situational method. The approach considers different method engineering situations and provides guidelines supporting method requirements definition in each of them. The application examples illustrate our approach throughout the paper.