Reinforcement learning (RL) is an important class of machine learning techniques, in which intelligent agents optimize their behavior by observing and evaluating the outcomes of their repeated interactions with their environment. A key to successfully engineering such agents is to provide them with the opportunity to engage in a large number of such interactions safely and at a low cost. This is often achieved through developing simulators of such interactions, in which the agents can be trained while also different training strategies and parameters are explored. However, specifying and implementing such simulators can be a complex endeavor requiring a systematic process for capturing and analyzing both the goals and actions of the agents and the characteristics of the target environment. We propose a framework for model-driven goal-oriented development of RL simulation environments. The framework utilizes a set of extensions to a standard goal modeling notation that allows concise modeling of a large number of ways by which an intelligent agent can interact with its environment. Through subsequent formalization, the model is used by a specially constructed simulation engine to simulate agent behavior, such that off-the-shelf RL algorithms can use it as a training environment. We present the extension of the goal modeling language and its semantics, and show how models built with it can be made executable. Further, we introduce a model development and transformation toolset to allow efficient generation and execution of simulator specifications. Through experimental studies we show how the proposed language and tool can be used for assisting the RL engineering process.

We offer a retrospective on a paper published in the IEEETransactions on Software Engineeringin 1992, hereafterthe NFR paper, that recently won a Most Influential Paper award. We first present the main contributions of the NFR paper, followed by subsequent work that extended and improved these contributions and discuss their impact. We conclude with retrospective remarks on the strengths and weaknesses of the NFR paper proposal.

SymboleoNLP is a Web-based tool that allows contract authors to make customizations to a legal contract template using a controlled, yet expressive, natural language. The tool also maintains a formal specification of the contract in Symboleo, a formal specification language designed for the legal contract monitoring domain. The controlled customizations allow for the automated formalization of the customized contract, enabling Symboleo-based property verification and code generation of monitoring smart contracts. This work pushes the boundaries of requirements-based contract template customization with a view towards full formalization.

Industrial control systems (ICSs), such as Supervisory Control and Data Acquisition (SCADA) systems, are increasingly popular for manufacturing applications, leading to significant improvements in efficiency and productivity. However, the vulnerability of these systems to ransomware attacks has become a major concern. This vulnerability is mainly due to the centralized nature of ICSs, which prioritize efficiency over security. To address this issue, this paper proposes a decentralized Blockchain-Based ICS (BBICS) architecture. Such architecture uses a peer-to-peer network of nodes to replicate critical data and distribute transactions using a consensus mechanism, which synchronizes nodes and resolves single points of failure. Additionally, BBICS encrypts critical data in a tamper-resistant manner to prevent attackers from decrypting or manipulating data. Moreover, zero-trust authorization and authentication further enhance security by preventing the broadcasting of ransomware attacks in internal networks of devices. The evaluation of the proposed system with respect to performance and reliability under normal and ransomware attack situations suggest BBICS’ feasibility and practicality.

Automated formalization of legal texts in order to remove ambiguities, conflicts and incompleteness has been a challenge for Requirements Engineering (RE) research for decades. This work seeks to make an incremental step towards this objective for legal contracts by making use of contract templates. Our proposed approach starts with a natural language contract template, together with a manually formalized specification of that template. A contract writer can make customizations to the template, which trigger the automatic formalization of the corresponding customized contract. Our target specification language is Symboleo, which is created specifically for contract verification and monitoring. Starting with a manually formalized template reduces the complexity associated with a fully automated formalization. Typical contract templates use simple fill-in-the-blank parameters, which serve as customizations to formalize in our framing of the problem. Our approach pushes the boundaries of these templates by allowing the contract writer to enter complex natural language customizations, such as prepositional phrases and conditional statements. This work explores what types of natural language patterns can be used in that context by analyzing relevant linguistics and real legal contracts. It also introduces a tool, SymboleoNLP, that suggests the feasibility of the formalization process.

Abstract In a world where Artificial Intelligence (AI) is pervasive, humans may feel threatened or at risk by giving up control to machines. In this context, ethicality becomes a major concern to prevent AI systems from being biased, making mistakes, or going rogue. Requirements Engineering (RE) is the research area that can exert a great impact in the development of ethical systems by design. However, proposing concepts, tools and techniques that support the incorporation of ethicality into the software development processes as explicit requirements remains a great challenge in the RE field. In this paper, we rely on Ontology-based Requirements Engineering (ObRE) as a method to elicit and analyze ethicality requirements (‘Ethicality requirements’ is adopted as a name for the class of requirements studied in this paper by analogy to other quality requirements studied in software engineering, such as usability, reliability, and portability, etc. The use of this term (as opposed to ‘ethical requirements’) highlights that they represent requirements for ethical systems, analogous to how ‘trustworthiness requirements’ represent requirements for trustworthy systems. To put simply: the predicates ‘ethical’ or ‘trustworthy’ are not meant to be predicated over the requirements themselves). ObRE applies ontological analysis to ontologically unpack terms and notions that are referred to in requirements elicitation. Moreover, this method instantiates the adopted ontology and uses it to guide the requirements analysis activity. In a previous paper, we presented a solution concerning two ethical principles, namely Beneficence and Non-maleficence. The present paper extends the previous work by targeting two other important ethicality principles, those of Explicability and Autonomy. For each of these new principles, we do ontological unpacking of the relevant concepts, and we present requirements elicitation and analysis guidelines, as well as examples in the context of a driverless car case. Furthermore, we validate our approach by analysing the requirements elicitation made for the driverless car case in contrast with a similar case, and by assessing our method’s coverage w.r.t European Union guidelines for Trustworthy AI.

Legal contracts specify requirements for business transactions. As any other requirements specification, contracts may contain errors and violate properties expected by contracting parties. Symboleo was recently proposed as a formal specification language for legal contracts. This paper presents SymboleoPC, a tool for analyzing Symboleo contracts using model checking. It highlights the architecture, implementation and testing of the tool, as well as a scalability evaluation with respect to the size of contracts and properties to be checked through a series of experiments. The results suggest that SymboleoPC can be usefully applied to the analysis of formal specifications of contracts with real-life sizes and structures.

Smart contracts (SCs) are software systems that monitor and control the execution of legal contracts to ensure compliance with the contracts' terms and conditions. They often exploit Internet-of-Things technologies to support their monitoring functions, and blockchain technology to ensure the integrity of their data. Ethereum and business blockchain platforms, such as Hyperledger Fabric, are popular choices for SC development. However, there is a gap in the knowledge of SCs between developers and legal experts. Symboleo is a formal specification language for legal contracts that was introduced to address this issue. Symboleo specifications directly encode legal concepts such as parties, obligations, and powers. In this paper, we propose a tool-supported method for translating Symboleo specifications into smart contracts. We have extended the current Symboleo IDE, implemented the ontology and semantics of Symboleo into a reusable library, and developed the Symboleo2SC tool to generate Hyperledger Fabric code exploiting this library. Symboleo2SC was evaluated with three sample contracts. The results shows that legal contract specifications in Symboleo can be fully converted to SCs for monitoring purposes. Moreover, Symboleo2SC helps simplify the SC development process, saves development effort, and helps reduce risks of coding errors.

Legal contracts specify the terms and conditions (in essence, requirements) that apply to business transactions. Smart contracts are software systems that monitor and control the execution of contracts to ensure compliance. This paper proposes a formal specification language for contracts, called Symboleo, where contracts consist of collections of obligations and powers that define the legal contract's compliant executions. The formal semantics of Symboleo is based on an extension of an ontology for Law and is described in terms of logical axioms on statecharts that describe the lifetimes of contracts, obligations and powers. Our proposal includes a preliminary evaluation through the specification of a real life-inspired Sale-of-Goods contract, with a prototype execution engine. We envision this language to enable formally verifying contracts to detect requirements-level issues and to generate executable smart contracts (e.g., on blockchain technology).

This paper contributes to the philosophical foundations of conceptual modeling by addressing a number of foundational questions such as: What is a conceptual model? Among models used in computer science, which are conceptual, and which are not? How are conceptual models different from other models used in the Sciences and Engineering? The paper takes a stance in answering these questions and, in order to do that, it draws from a broad literature in philosophy, cognitive science, Logics, as well as several areas of Computer Science (including Databases, Software Engineering, Artificial Intelligence, Information Systems Engineering, among others). After a brief history of conceptual modeling, the paper addresses the aforementioned questions by proposing a characterization of conceptual models with respect to conceptual semantics and ontological commitments. Finally, we position our work w.r.t. to a "Reference Framework for Conceptual" modeling recently proposed in the literature.

The requirements problem consists of transforming stakeholder requirements - however informal, ambiguous, conflicting, unattainable, imprecise and incomplete – into a consistent, complete and realizable specification through a systematic process. We propose a refinement calculus for requirements engineering (CaRE) for solving this problem, which is inspired by the typically dialectical nature of requirements activities. The calculus casts the requirement problem as an iterative argument between stakeholders and requirements engineers, where posited requirements are attacked for being ambiguous, incomplete, etc. and refined into new requirements that address the defect pointed out by the attack. Refinements are carried out by operators provided by CaRE that refine (e.g., strengthen, weaken, decompose) existing requirements to eliminate the defect under attack, to build a refinement graph. The semantics of refinement graphs is based on the notion of acceptable argument in Dung’s argumentation theory.

Gamification is increasingly applied to engage people in performing tool-supported collaborative tasks. From previous experiences we learned that available gamification guidelines are not sufficient, and more importantly that motivational and acceptance aspects need to be considered when designing gamified software applications. To understand them, stakeholders need to be involved in the design process. This paper aims to (i) identify key requirements for designing gamified solutions, and (ii) understand if existing methods (partially fitting those requirements) can be selected and combined to provide a comprehensive gamification design method. We discuss a set of key requirements for a suitable gamification design method. We illustrate how to select and combine existing methods to define a design approach that fits those requirements usingDesign Thinking and the Agon framework. Furthermore, we present a first empirical evaluation of the integrated design method, with participants including both requirements analysts and end-users of the gamified software. Our evaluation offers initial ideas towards a more general, systematic approach for gamification design.

Over the last two decades, much attention has been paid to the area of goal-oriented requirements engineering (GORE), where goals are used as a useful conceptualization to elicit, model, and analyze requirements, capturing alternatives and conflicts. Goal modeling has been adapted and applied to many sub-topics within requirements engineering (RE) and beyond, such as agent orientation, aspect orientation, business intelligence, model-driven development, and security. Despite extensive efforts in this field, the RE community lacks a recent, general systematic literature review of the area. In this work, we present a systematic mapping study, covering the 246 top-cited GORE-related conference and journal papers, according to Scopus. Our literature map addresses several research questions: we classify the types of papers (e.g., proposals, formalizations, meta-studies), look at the presence of evaluation, the topics covered (e.g., security, agents, scenarios), frameworks used, venues, citations, author networks, and overall publication numbers. For most questions, we evaluate trends over time. Our findings show a proliferation of papers with new ideas and few citations, with a small number of authors and papers dominating citations; however, there is a slight rise in papers which build upon past work (implementations, integrations, and extensions). We see a rise in papers concerning adaptation/variability/evolution and a slight rise in case studies. Overall, interest in GORE has increased. We use our analysis results to make recommendations concerning future GORE research and make our data publicly available.

Strategic goals and strategic planning have received much attention in Management Sciences literature since the 60s. In this work, we are interested in putting strategic planning on a formal, algorithmic footing by offering a formal reasoning technique for automatic generation and selection of strategic plans. Towards this end, in previous work [1] we have introduced the concept of strategic goals and dimensional refinement operators that define strategic goals in terms of domain dimensions from the data warehouses literature. Examples of dimensions for a strategic goal such as "Increase sales in Europe over 2 years" might include time, geography and product type. Here, we propose a formalization of strategic goals and their dimensional refinements that allows one to express a strategic goal model as a planning space that can be achieved across different dimensions. Subsequently, we use automated reasoning solvers to produce optimum strategic plans to achieve such strategic goals. Our proposal is illustrated with an example from the literature.

It is widely recognized that accurately identifying and classifying competitors is a challenge for many companies and entrepreneurs. Nonetheless, it is a paramount activity which provide valuable insights that affect a wide range of strategic decisions. One of the main challenges in competitor identification lies in the complex nature of the competitive relationships that arise in business environments. These have been extensively investigate over the years, which lead to a plethora of competition theories and frameworks. Still, the concept of competition remains conceptually complex, as none of these approaches properly formalized their assumptions. In this paper, we address this issue by means of an ontological analysis on the notion of competition in general, and of business competition, in particular, leveraging theories from various fields, including Marketing, Strategic Management, Ecology, Psychology and Cognitive Sciences. Our analysis, the first of its kind in the literature, is grounded on the Unified Foundational Ontology (UFO) and allows us to formally characterize why competition arises, as well as to distinguish between three types of business competitive relationships, namely market-level, firm-level and potential competition.

We study the problem of finding related forum posts to a post at hand. We developed a multi-segment matching technique that considers posts as a set of segments each one written with a different goal in its author mind and computes the relatedness between two posts based on the similarity of their respective segments that are intended for the same goal. The questions are how our method identifies such segments, how it figures out for what each segment is intended and how it exploits this information to rank the posts. We experimentally illustrate the effectiveness and efficiency of our segmentation method and overall approach of finding related forum posts.

Context. Goal models have long been critiqued for the time it takes to construct them as well as for their limited cognitive and visual scalability. Is such criticism general or does it depend on the supported task? Objectives. We advocate for the latter and the aim of this paper is to demonstrate that the next release problem is a suitable application domain for goal models. This hypothesis stems from the fact that product release management is a long-term investment, and software products are commonly managed in "themes" which are smaller focus areas of the product. Methods. We employ a version of goal models that is tailored for the next release problem by capturing requirements, synergies among them, constraints, and release objectives. Such goal model allows discovering optimal solutions considering multiple criteria for the next release. Results. A retrospective case study confirms that goal models are easier to read and comprehend when organized in themes, and that the reasoning results help product managers decide for the next release. Our scalability experiments show that, through reasoning based on optimization modulo theories, the discovery of the optimal solution is fast and scales sufficiently well with respect to the model size, connectivity, and number of alternative solutions.

The requirements problem consists of transforming stakeholder requirements - however informal, ambiguous, conflicting, unattainable, imprecise and incomplete – into a consistent, complete and realizable specification through a systematic process. We propose a refinement calculus for requirements engineering (CaRE) for solving this problem, which takes into account the typically dialectic nature of requirements activities. The calculus casts the requirement problem as an iterative argument between stakeholders and requirements engineers, where posited requirements are attacked for being ambiguous, incomplete, etc. and refined into new requirements that address the defect pointed out by the attack. Refinements are carried out by operators provided by CaRE that refine (e.g., strengthen, weaken, decompose) existing requirements, to build a refinement graph. The semantics of the operators is provided by means of argumentation theory. Examples are given to illustrate the elements of our proposal.

Self-adaptive software systems monitor their operation and adapt when their requirements fail due to unexpected phenomena in their environment. This article examines the case where the environment changes dynamically over time and the chosen adaptation has to take into account such changes. In control theory, this type of adaptation is known as Model Predictive Control and comes with a well-developed theory and myriad successful applications. The article focuses on modeling the dynamic relationship between requirements and possible adaptations. It then proposes a controller that exploits this relationship to optimize the satisfaction of requirements relative to a cost function. This is accomplished through a model-based framework for designing self-adaptive software systems that can guarantee a certain level of requirements satisfaction over time by dynamically composing adaptation strategies when necessary. The proposed framework is illustrated and evaluated through two simulated systems, namely, the Meeting-Scheduling exemplar and an E-Shop.

Users increasingly depend on mobile applications to get access to software services, social networks, and physical devices. When using mobile applications, users often want to achieve personal goals rather than merely perform individual tasks. To achieve a goal, a user often needs to combine software services, social cooperation, and possibly manual work. Moreover, a goal can often be achieved in different ways, each of which involves an alternative sequence of tasks. Accordingly, mobile applications should be customizable, to accommodate user preferences, and adaptive in changing their configuration automatically if the current configuration is failing. In this paper, we propose an improved runtime goal model that can manage runtime lifecycle of goals and adaptively schedule the activation of goals and execution of tasks. Based on the model, we propose an agent-based framework called MobiGoal, which combines software services, social cooperation, and manual work for achieving user goals and provides an infrastructure for developing customizable and adaptive mobile applications for personal goals. We have developed an implementation for Android platform and conducted an empirical study. The results show that MobiGoal applications can effectively support users to adaptively achieve their goals and MobiGoal can significantly save effort of application development for specific goals.

In competitive markets, companies need well-designed business strategies if they seek to grow and obtain sustainable competitive advantage. At the core of a successful business strategy there is a carefully crafted value proposition, which ultimately defines what a company delivers to its customers. Despite their widely recognized importance, there is however little agreement on what exactly value propositions are. This lack of conceptual clarity harms the communication among stakeholders and the harmonization of current business strategy theories and strategy support frameworks. Furthermore, it hinders the development of systematic methodologies for crafting value propositions, as well as adequate support for representing and analyzing them. In this paper, we present an ontological analysis of value propositions based on a review of most relevant business and marketing theories and on previous work on value ascription, grounded in the Unified Foundational Ontology (UFO). Our investigation clarifies how value propositions are different from value presentations, and shows the difference between value propositions at the business level from those related to specific offerings.

Regulations constitute a rich source of requirements for software systems, especially so for information systems that handle sensitive data. However, there has been little attention paid to regulators and their requirements for managing the regulatory lifecycle. This paper presents a study of the state-of-practice for regulators in Canada by examining seven Government of Canada (GoC) agencies responsible for regulations. In each case, we attempt to capture the context within which regulations are created, the motivation behind these regulations, and the practices related to their design, enforcement, and review. Our aims are to understand how regulators currently design, monitor, and assess regulations and other regulatory instruments in their respective domains, and to identify opportunities where information system (IS) solutions can be applied to improve practice. Our field study involved reviewing publicly available information and conducting informal interviews. Together, these activities helped us understand key regulators' activities and concerns, as well as important challenges they currently face. In this paper, we summarize our findings and explain the implications for the use of ISs to improve the practice of regulatory management in the form of a research agenda.

Laws and regulations impact the design of software systems, as they may introduce additional requirements and possible conflicts with pre-existing requirements. We propose a systematic, tool-supported process for establishing compliance of a software system with a given law. The process elicits new requirements from the law, compares them with existing ones and manages conflicts, exploiting a set of heuristics, partially supported by a tool. We illustrate our proposal through an exploratory study using the Italian Privacy Law. We also present results of a preliminary empirical study that indicates that adoption of the process improves compliance analysis for a simple compliance scenario.

Gamification is a powerful paradigm and a set of best practices used to motivate people carrying out a variety of ICT-mediated tasks. Designing gamification solutions and applying them to a given ICT system is a complex and expensive process (in time, competences and money) as software engineers have to cope with heterogeneous stakeholder requirements on one hand, and Acceptance Requirements on the other, that together ensure effective user participation and a high level of system utilization. As such, gamification solutions require significant analysis and design as well as suitable supporting tools and techniques. In this work, we compare concepts, tools and techniques for gamification design drawn from Software Engineering and Human and Organizational Behaviors. We conduct a comparison by applying both techniques to the specific Meeting Scheduling exemplar used extensively in the Requirements Engineering literature.

Security has been a growing concern for large organizations, especially financial and governmental institutions, as security breaches in the systems they depend on have repeatedly resulted in billions of dollars in losses per year, and this cost is on the rise. A primary reason for these breaches is that the systems in question are socio-technical - a mix of people, processes, technology and infrastructure. However, such systems are designed in a piecemeal rather than a holistic fashion, leaving parts of the system vulnerable. To tackle this problem, a three-realm security requirements framework was proposed to holistically analyse security requirements in different conceptual realms, including social realm (business processes, social actors), a software realm (software applications that support the social realm) and an infrastructure realm (physical and technological infrastructure). In this paper we evaluate this security requirements analysis framework. The evaluation was performed by two graduate students using a large scale case study on a medical emergency response system.

Context and Motivation Natural language processing has been used since the 1980s to construct tools for performing natural language (NL) requirements engineering (RE) tasks. The RE field has often adopted information retrieval (IR) algorithms for use in implementing these NL RE tools. Problem Traditionally, the methods for evaluating an NL RE tool have been inherited from the IR field without adapting them to the requirements of the RE context in which the NL RE tool is used. Principal Ideas This panel discusses the problem and considers the evaluation of tools for a number of NL RE tasks in a number of contexts. Contribution The discussion is aimed at helping the RE field begin to consistently evaluate each of its tools according to the requirements of the tool's task.

We study the problem of finding related forum posts to a post at hand. In contrast to traditional approaches for finding related documents that perform content comparisons across the content of the posts as a whole, we consider each post as a set of segments, each written with a different goal in mind. We advocate that the relatedness between two posts should be based on the similarity of their respective segments that are intended for the same goal, i.e., are conveying the same intention. This means that it is possible for the same terms to weigh differently in the relatedness score depending on the intention of the segment in which they are found. We have developed a segmentation method that by monitoring a number of text features can identify the parts of a post where significant jumps occur indicating a point where a segmentation should take place. The generated segments of all the posts are clustered to form intention clusters and then similarities across the posts are calculated through similarities across segments with the same intention. We experimentally illustrate the effectiveness and efficiency of our segmentation method and our overall approach of finding related forum posts.

Dealing with multiple requirement failures is an essential capability for self-adaptive software systems. This capability becomes more challenging in the presence of conflicting goals. This paper is concerned with the next adaptation problem: the problem of finding the best next adaptation in the presence of multiple failures. ‘Best’ here means that the adaptation chosen optimizes a given set of objective functions, such as the cost of adaptation or the degree of failure for system requirements. The paper proposes a formal framework for defining the next adaptation problem, assuming that we can specify quantitatively the constraints that hold between indicators that measure the degree of failure of each requirement and control parameters. These constraints, along with one or several objective functions, are translated into a constrained multi-objective optimization problem that can be solved by using an OMT/SMT (Optimization Modulo Theories/Satisfiability Modulo Theories) solver, such as OptiMathSAT. The proposed framework is illustrated with the Meeting Scheduler exemplar and a second, e-shop case study.

Risks of software projects are often ignored and risk analysis is left for later stages of project life-cycle, resulting in serious financial losses. This paper proposes a goal-oriented risk analysis framework that includes inter-dependencies among treatments and risks in terms of likelihood and generate optimal solutions with respect to multiple objectives such as goal rewards, treatment costs, or risk factor. The Loan Origination Process illustrates our approach and a detailed analysis of the visual notation is provided.

Discovering potential attacks on a system is an essential step in engineering secure systems, as the identified attacks will determine essential security requirements. The prevalence of Socio-Technical Systems (STSs) makes attack analysis particularly challenging. These systems are composed of people and organizations, their software systems, as well as physical infrastructures. As such, a thorough attack analysis needs to consider strategic (social and organizational) aspects of the involved people and organizations, as well as technical aspects affecting software systems and the physical infrastructure, requiring a large amount of security knowledge which is difficult to acquire. In this paper, we propose a systematic approach to efficiently leverage a comprehensive attack knowledge repository (CAPEC) in order to identify realistic and detailed attack behaviors, avoiding severe repercussions of security breaches. In particular, we propose a systematic method to model CAPEC attack patterns, which has been applied to 102 patterns, in order to semi-automatically select and apply such patterns. Using the CAPEC patterns as part of a systematic and tool-supported process, we can efficiently operationalize attack strategies and identify realistic alternative attacks on an STS. We validate our proposal by performing a case study on a smart grid scenario.

The requirements for most software systems - the intended states-of-affairs these systems are supposed to bring about - concern their operational environment, often a socio-physical world. But software systems usually don't have any direct means to change that environment in order to bring about the intended states-of-affairs. In what sense then can we say that such systems fulfill their requirements? The main purpose of this paper is to account for this paradox. We do so by proposing a preliminary Ontology of Assumptions. This ontology aims to characterize and make explicit a number of notions that are used implicitly in software engineering practice to establish that a system specification S fulfills its requirements R given a set of assumptions A. Our proposal is illustrated with an example concerning a meeting scheduler.

Over the last two decades, much attention has been paid to the area of Goal-Oriented Requirements Engineering(GORE), where goals are used as a useful conceptualization to elicit, model and analyze requirements, capturing alternatives and conflicts. Goal modeling has been adapted and applied to many sub-topics within RE and beyond, such as agent-orientation, aspect-orientation, business intelligence, model-driven development, security, and so on. Despite extensive efforts in this field, the RE community lacks a recent, general systematic literature review of the area. As a first step towards providing a GORE overview, we present a Systematic Literature Map, focusing on GORE-related publications at a high-level, categorizing and analyzing paper information in order to answer several research questions, while omitting a detailed analysis of individual paper quality. Our Literature Map covers the 246 top-cited GORE-related conference and journal papers, according to Scopus, classifying them into a number of descriptive paper types and topics, providing an analysis of the data, which is made publicly available. We use our analysis results to make recommendations concerning future GORE research.

We live in the days of social software where social interactions, from simple notifications to complex business processes, are supported by software platforms such as Facebook and Twitter. But for any social software to be successful, it must be used by a sizeable portion of its intended user community. Usage requirements are usually referred to as Acceptance Requirements and they have been studied in the literature both for general technology as well as software. Operationalization techniques for such requirements often consist of making a game out of software usage where users are rewarded/penalized depending onthe degree of their participation. The game may be competitive or non-competitive, depending on the anticipated personality traits of intended users. Making a game out of usage is often referred to as Gamification, and gamification has attracted huge attention in the literature for the past few years because it offers a novelapproach to software technology usage. This paper proposes a generic framework for designing gamified solutions for acceptance requirements. The framework consists of a generic acceptance goal model that characterizes the problem space by capturing possible refinements for acceptance requirements, and a generic gamification model that capturespossible gamified operationalizations of acceptance requirements. These models have been extracted from the literature and they are highly dependent on context (cognitive and social) elements of the intended user community. The proposed framework isillustrated with the Meeting Scheduler exemplar.

Human activity is almost always intentional, be it in a physical context or as part of an interaction with a computer system. By understanding why user-generated events are happening and what purposes they serve, a system can offer a significantly improved and more engaging experience. However, goals cannot be easily captured. Analyzing user actions such as clicks and purchases can reveal patterns and behaviors, but understanding the goals behind these actions is a different and challenging issue. Our work presents a unified, multidisciplinary viewpoint for goal management that covers many different cases where goals can be used and techniques with which they can be exploited. Our purpose is to provide a common reference point to the concepts and challenging tasks that need to be formally defined when someone wants to approach a data analysis problem from a goal-oriented point of view. This work also serves as a springboard to discuss several open challenges and opportunities for goal-oriented approaches in data management, analysis, and sharing systems and applications.

Business analytics has emerged in the past decade as a top concern for business executives world-wide, surpassing earlier top concerns such as supply chain management and total quality management. Business analysis techniques analyze operational data for a variety of purposes including prediction, planning, monitoring, and trouble-shooting. In this paper we focus on one type of analysis, monitoring operational data to determine whether a business is on track relative to its strategic goals. If deviations exists, our approach narrows the search to the most problematic instances detected. Furthermore, we show how the process can be fully automated including the generation of all necessary queries. Finally, we show how the monitoring process has been implemented in our tool, Argus, which enables the analysis of arbitrary periods of time. Our prototype has been evaluated using a small data warehouse of synthetic data.

This tutorial provides a comprehensive and cohesive overview of goal modeling and recognition approaches by the Information Retrieval, the Artificial Intelligence and the Social Media communities. We will examine how these fields restrict the domain of study and how they capture notions easily perceived by humans' intuition but difficult to be formally defined and handled algorithmically. It is the purpose of this tutorial to provide a solid framework for placing existing work into perspective and highlight critical open challenges that will act as a springboard for researchers and practitioners in database systems, social data, and the Web, as well as developers of web-based, database-driven, and social applications, to work towards more user-centric systems and applications.

Question-oriented text retrieval, aka natural language-based text retrieval, has been widely used in software engineering. Earlier work has concluded that questions with the same keywords but different interrogatives (such as how, what) should result in different answers. But what is the difference? How to identify the right answers to a question? In this paper, we propose to investigate the "answer style" of software questions with different interrogatives. Towards this end, we build classifiers in a software text repository and propose a re-ranking approach to refine search results. The classifiers are trained by over 16,000 answers from the StackOverflow forum. Each answer is labeled accurately by its question's explicit or implicit interrogatives. We have evaluated the performance of our classifiers and the refinement of our re-ranking approach in software text retrieval. Our approach results in 13.1% and 12.6% respectively improvement with respect to text retrieval criteria nDCG@1 and nDCG@10 compared to the baseline. We also apply our approach to FAQs of 7 open source projects and show 13.2% improvement with respect to nDCG@1. The results of our experiments suggest that our approach could find answers to FAQs more precisely.

A business process is first and foremost a social interaction among multiple participants. Business process modeling languages support the description of business processes in operational terms, as collections of interleaved activities conducted by human and software agents. However, such descriptions do not capture adequately the richness of social interaction among participants. To address this deficiency, we propose Azzurra, a specification language for modeling and enacting business processes. Azzurra is founded on social concepts, such as roles, agents and commitments among them, and Azzurra specifications are social models consisting of sets of commitments. As such, Azzurra specifications support flexible executions of business processes, and provide a semantic notion of actor accountability and business process compliance. In this paper, we present syntax and semantics of Azzurra, and we propose algorithms to determine runtime compliance with an Azzurra specification.

The Tactical Business Intelligence Model (TBIM) is a language for modeling business tactics. TBIM models act as a bridge between the strategic and tactical organizational levels, for the modeled tactics refine an organization's strategy, while needing further details to become operational. The purpose of TBIM models is to support decision making by representing and enabling the comparison of alternative plans for fulfilling an organization's strategic objectives. In this paper, we report on our experience in applying TBIM for modeling the Montreux Jazz Festival organization case study from the literature. In addition to showing TBIM models for different aspects of festival organization (ticketing and advertising, experience delivery, concerts and recordings), we discuss lessons learned.

The ever-growing complexity of systems makes their protection more challenging, as a single vulnerability or exposure of any component of the system can lead to serious security breaches. This problem is exacerbated by the fact that the system development community has not kept up with advances in attack knowledge. In this demo paper, we propose a holistic attack analysis approach to identify and tackle both atomic and multistage attacks, taking into account not only software attacks but also attacks that are targeted at people and hardware. To bridge the knowledge gap between attackers and defenders, we systematically analyze and refine the malicious desires of attackers (i.e., anti-goals), and leverage a comprehensive attack pattern repository (CAPEC) to operationalize attacker goals into concrete attack actions. Based on the results of our attack analysis, appropriate security controls can be selected to effectively tackle potential attacks.

We have been witnessing growing interest in systems that can adapt their behavior to deal with deviations between their performance and their requirements at run-time. Such adaptive systems usually need to support some form of a feedback loop that monitors the system's output for problems and carries out adaptation actions when necessary. Being an important feature, adaptivity needs to be considered in early stages of development. Therefore, adopting a requirements engineering perspective, we have proposed an approach and a framework (both called Zanshin) for the engineering of adaptive systems based on a feedback loop architecture. As part of our framework's evaluation, we have applied the Zanshin approach to the design of an adaptive computer-aided ambulance dispatch system, whose requirements were based on a well-known case study from the literature. In this paper, we report on the application of Zanshin for the design of an adaptive computer-aided ambulance dispatch system, presenting elements of the design, as well as the results from simulations of run-time scenarios. Copyright © 2013 John Wiley & Sons, Ltd.

Non-functional requirements (NFRs) have been the focus of research in Requirements Engineering (RE) for more than 20 years. Despite this attention, their ontological nature is still an open question, thereby hampering efforts to develop concepts, tools and techniques for eliciting, modeling, and analyzing them, in order to produce a specification for a system-to-be. In this paper, we propose to treat NFRs as qualities, based on definitions of the UFO foundational ontology. Furthermore, based on these ontological definitions, we provide guidelines for distinguishing between non-functional and functional requirements, and sketch a syntax of a specification language that can be used for capturing NFRs.

Although software plays an essential role in modern society, its ontological nature is still unclear. For many, software is just code, but this is not illuminating. Several researchers have attempted to understand the core nature of software and programs in terms of concepts such as code, copy, medium and execution. More recently, a proposal was made to consider software as an abstract artifact, distinct from code, just because code may change while the software remains the same. We explore in this paper the implications of such a proposal in the light of software engineering and requirements engineering literature. We make a sharp distinction between different kinds of software artifacts (code, program, software system, and software product), and describe the ways they are inter-connected in the context of a software engineering process.

Socio-technical systems (STSs) consist of human, hardware and software agents that work in tandem to fulfill stakeholder requirements. A specification for an STS consists of a set of (social) commitments among participating agents that serve as a contract among them. However, by their very nature, STSs are open, dynamic and continuously evolving along with their environments. To ensure that such systems continue to satisfy their requirements, the agents that comprise an STS must continuously adapt their behaviors to take into account risks and opportunities that arise at runtime. This paper presents a decision-theoretic self-adaptation framework that proposes candidate adaptation strategies for participating agents. These strategies are implementable by reconfiguration of plans or even changes in contractual commitments among agents. The adaptation procedure involves negotiating commitment changes and possible compensations to/from creditor agents. To evaluate the proposal, the paper also presents the results of an experimental study with a simulated STS, which confirms that success rates for achieving stakeholder goals and overall trade off utility can be improved significantly by incorporating evolving commitments to support STS adaptation.

Sociotechnial systems (STSs) consist of a complex interplay of technical components, humans, and organizations. As other types of systems, STSs need to evolve in response to changing requirements and operational environments. Evolving STSs is a complex activity, which requires reconfiguration of technical components as well as rerouting of interactions among human and social actors. Moreover, reconfiguration has to respect participant autonomy, while coping with conflicting goals and noncooperation in identifying a configuration that minimizes changes relative to the current configuration. In this paper, we present a framework that supports design and evolution of STSs. The framework includes (i) the DEST language for modeling STSs as goal-oriented actors that interact via social commitments; (ii) techniques for building a network of interactions that fulfills participant requirements; and (iii) techniques for evolving an existing STS while minimizing change. We encode the design and evolution of STSs as an automated planning problem.

Creating and reasoning with goal models is useful for capturing, understanding, and communicating about requirements in the early stages of information system (re)development. However, the utility of goal models is greatly enhanced when an awareness of system intentions can feed into other stages in the requirements analysis process (e.g. requirements elaboration, validation, planning), and can be used as part of the entire system life cycle (e.g., architecture, process design, coding, testing, monitoring, adaptation, and evolution). In order to understand the progress that has been made in integrating goal models with downstream system development, we ask: what approaches exist which map/integrate/transform goal-oriented languages to other software artifacts or languages? To answer this question, we conduct a systematic survey, producing a roadmap of work summarizing 174 publications. Results include a categorization of the “why?” and “how?” for each approach. Findings show that there are a wide variety of proposals with many proposed sources and targets, covering multiple paradigms, motivated by a variety of purposes. We conclude that although much work has been done in this area, the work is fragmented and is often still in a proposal stage.

We address the challenge of requirements engineering for sociotechnical systems, wherein humans and organizations supported by technical artifacts such as software interact with one another. Traditional requirements models emphasize the goals of the stakeholders above their interactions. However, the participants in a sociotechnical system may not adopt the goals of the stakeholders involved in its specification. We motivate, Protos, a requirements engineering approach that gives prominence to the interactions of autonomous parties and specifies a sociotechnical system in terms of its participants' social relationships, specifically, commitments. The participants can adopt any goal they like, a key basis for innovative behavior, as long as they interact according to the commitments. Protos describes an abstract requirements engineering process as a series of refinements that seek to satisfy stakeholder requirements by incrementally expanding a specification set and an assumption set, and reducing requirements until all requirements are accommodated. We demonstrate this process via the London Ambulance System described in the literature.

The great impact that law has in the RE-process has called for new techniques and procedures to evaluate the alignment of requirements with applicable laws. In this paper we present a modeling language for the evaluation of compliance of requirements with a piece of law: Nòmos 3. We introduce our language and show the reasoning capabilities of our proposal.

We propose a modeling language for non-functional requirements (NFRs) that views NFRs as requirements over qualities, mapping a software-related domain to a quality space. The language is compositional in that it allows (recursively) complex NFRs to be constructed in several ways. Importantly, the language allows the definition of requirements about the quality of fulfillment of other requirements, thus capturing, among others, the essence of probabilistic and fuzzy goals as proposed in the literature. We also offer a methodology for systematically refining informal NFRs elicited from stakeholders, resulting in unambiguous, de-idealized, and measurable requirements. The proposal is evaluated with a requirements dataset that includes 370 NFRs crossing 15 projects. The results suggest that our framework can adequately handle and clarify NFRs generated in practice.

Requirements-driven approaches provide an effective mechanism for self-adaptive systems by reasoning over their runtime requirements models to make adaptation decisions. However, such approaches usually assume that the relations among alternative behaviours, environmental parameters and requirements are clearly understood, which is often simply not true. Moreover, they do not consider the influence of the current behaviour of an executing system on adaptation decisions. In this paper, we propose an improved requirements-driven self-adaptation approach that combines goal reasoning and case-based reasoning. In the approach, past experiences of successful adaptations are retained as adaptation cases, which are described by not only requirements violations and contexts, but also currently deployed behaviours. The approach does not depend on a set of original adaptation cases, but employs goal reasoning to provide adaptation solutions when no similar cases are available. And case-based reasoning is used to provide more precise adaptation decisions that better reflect the complex relations among requirements violations, contexts, and current behaviours by utilizing past experiences. Our experimental study with an online shopping benchmark shows that our approach outperforms both requirements-driven approach and case-based reasoning approach in terms of adaptation effectiveness and overall quality of the system.

In this position paper we review the history of requirements models and conclude that a goal-oriented perspective offers a suitable abstraction for requirements analysis. We stake positions on the nature of modelling languages in general, and requirements modelling languages in particular. We then sketch some of the desirable features (... “requirements”) of design-time and runtime requirements models and draw conclusions about their similarities and differences.

Goal models capture stakeholder requirements for a system-to-be, but also circumscribe a space of alternative specifications for fulfilling these requirements. Recent proposals for self-adaptive software systems rely on variants of goal models to support monitoring and adaptation functions. In such cases, goal models serve as mechanisms in terms of which systems reflect upon their requirements during their operation. We argue that existing proposals for using goal models at runtime are using design artifacts for purposes they were not intended, i.e., for reasoning about runtime system behavior. In this paper, we propose a conceptual distinction between Design-time Goal Models (DGMs)-used to design a system-and Runtime Goal Models (RGMs)-used to analyze a system's runtime behavior with respect to its requirements. RGMs extend DGMs with additional state, behavioral and historical information about the fulfillment of goals. We propose a syntactic structure for RGMs, a method for deriving them from DGMs, and runtime algorithms that support their monitoring.

This position paper argues that industry tracks have no place in any research conference. Instead, a research conference should always have room for industrial case studies, evaluated according to criteria for empirical research. Such case studies would not be acceptable at a practitioners' industrial conference, just as papers presented at such conferences would not be acceptable at research conferences. It follows as corollary that if researchers want to become familiar with problems and solutions of RE practice, they should visit industrial conferences.

Socio-technical systems consist of human, hardware and software components that work in tandem to fulfill stakeholder requirements. By their very nature, such systems operate under uncertainty as components fail, humans act in unpredictable ways, and the environment of the system changes. Self-repair refers to the ability of such systems to restore fulfillment of their requirements by relying on monitoring, reasoning, and diagnosing on the current state of individual requirements. Self-repair is complicated by the multi-agent nature of socio-technical systems, which demands that requirements monitoring and self-repair be done in a decentralized fashion. In this paper, we propose a stateful requirements monitoring approach by maintaining an instance of a state machine for each requirement, represented as a goal, with runtime monitoring and compensation capabilities. By managing the interactions between the state machines, our approach supports hierarchical goal reasoning in both upward and downward directions. We have implemented a customizable Java framework that supports experimentation by simulating a socio-technical system. Results from our experiments suggest effective and precise support for a wide range of self-repairing decisions in a socio-technical setting.

The problem of managing evolving data has attracted considerable research attention. Researchers have focused on the modeling and querying of schema/instance-level structural changes, such as, addition, deletion and modification of attributes. Databases with such a functionality are known as temporal databases. A limitation of the temporal databases is that they treat changes as independent events, while often the appearance (or elimination) of some structure in the database is the result of an evolution of some existing structure. We claim that maintaining the causal relationship between the two structures is of major importance since it allows additional reasoning to be performed and answers to be generated for queries that previously had no answers. We present here a novel framework for exploiting the evolution relationships between the structures in the database. In particular, our system combines different structures that are associated through evolution relationships into virtual structures to be used during query answering. The virtual structures define "possible" database instances, in a fashion similar to the possible worlds in the probabilistic databases. The framework includes a query answering mechanism that allows queries to be answered over these possible databases without materializing them. Evaluation of such queries raises many interesting technical challenges, since it requires the discovery of Steiner forests on the evolution graphs. On this problem we have designed and implemented a new dynamic programming algorithm with exponential complexity in the size of the input query and polynomial complexity in terms of both the attribute and the evolution data sizes.

In today's service computing environments, user needs and expectations are constantly changing. New services emerge while old ones become obsolete and need to be replaced. In such settings, composite services need to be adaptive to changes in user requirements and the environment. This paper proposes a conceptual framework for modeling compositional adaptation for services founded on a requirements monitoring facility. This facility helps maintain adherence between user requirements changes and the dynamics of service composition structure and quality attributes. Specifically, user requirements are represented as goals and soft goals, service composition structure is represented with a CSP-like grammar, and the adaptation mechanism is based on AI planning. The proposed approach is evaluated in a service simulation environment of real-world supply-chain adaptation scenarios.

Researchers have employed a variety of techniques to extract underlying topics that relate to software development artifacts. Typically, these techniques use semi-unsupervised machine-learning algorithms to suggest candidate word-lists. However, word-lists are difficult to interpret in the absence of meaningful summary labels. Current topic modeling techniques assume manual labelling and do not use domainspecific knowledge to improve, contextualize, or describe results for the developers. We propose a solution: automated labelled topic extraction. Topics are extracted using Latent Dirichlet Allocation (LDA) from commit-log comments recovered from source control systems such as CVS and Bit-Keeper. These topics are given labels from a generalizable cross-project taxonomy, consisting of non-functional requirements. Our approach was evaluated with experiments and case studies on two large-scale RDBMS projects: MySQL and MaxDB. The case studies show that labelled topic extraction can produce appropriate, context-sensitive labels relevant to these projects, which provides fresh insight into their evolving software development activities.

Problem diagnosis in large software systems is a challenging and complex task. The sheer complexity and size of the logged data make it often difficult for human operators and administrators to perform problem diagnosis and root cause analysis. A challenge in this area is to provide the necessary means, tools, and techniques for the operators to focus their attention to specific parts of the logged data reducing thus the complexity of the diagnostic process. In this paper, we propose a framework for filtering logs according to specific analysis goals and diagnostic hypotheses set by the user or by an automated process. More specifically, the proposed framework uses annotated goal trees to model the constraints and the conditions by which the functionality of a particular system is being delivered. Next, a transformation process maps such constraints and conditions to a collection of queries that can be either applied to a relational database that stores the logged data or use Latent Semantic Indexing to identify the most relevant log entries for the given query. The results of such queries provide a subset of the logged data that is compliant with the goal tree and can be used by a diagnostic SAT-solver based algorithm. Experimental results show that the filtering process can reduce the time and complexity of the diagnosis when applied to multi-tier heterogeneous service oriented systems.

Techne is an abstract requirements modeling language that lays formal foundations for new modeling languages applicable during early phases of the requirements engineering process. During these phases, the requirements problem for the system-to-be is being structured, its candidate solutions described and compared in terms of how desirable they are to stakeholders. We motivate the need for Techne, introduce it through examples, and sketch its formalization.

Requirements can differ in their importance. As such the priorities that stakeholders associate with requirements may vary from stakeholder to stakeholder and from one situation to the next. Differing priorities, in turn, imply different design decisions for the end system. While elicitation of requirements priorities is a well studied activity, though, the modeling and reasoning side of prioritization has not enjoyed equal attention. In this paper, we address this by extending a traditional goal modeling notation to support the representation of optional and preference requirements. In our extension, optional goals are distinguished from mandatory ones. Then, quantitative prioritizations of the former are constructed and used as criteria for evaluating alternative ways to achieve the latter. A state-of-the-art preference-based planner is utilized to efficiently search for alternatives that best satisfy the given preferences. This way, analysts can acquire a better understanding of the impact of high-level stakeholder preferences to low-level design decisions.

This is a demonstration of data coordination in a peer data management system through the employment of distributed triggers. The latter express in a declarative manner individual security and consistency requirements of peers, that cannot be ensured by default in the P2P environment. Peers achieve to handle in a transparent way data changes that come from local and remote actions and events. The distributed triggers are implemented as an extension of the active functionality of a centralized commercial DBMS. The language and execution semantics of distributed triggers are integrated in the kernel of the DBMS such that the latter handles transparently and simultaneously both centralized and distributed triggers. Moreover, the management of distributed triggers is associated with a set of peer acquaintance and termination protocols which are incorporated in the centralized DBMS.

In the services era, evaluation of existing services and planning for new services according to user requirements are key activities that need systematic support. This paper proposes a requirements-driven evaluation framework for Internetware-based services, with respect to both their functionality and risk. In particular, we offer an account of how to model these requirements, how to derive from them a space of service functionality alternatives, and how to select among these alternatives on the basis of desired qualities. In essence, the selection of service functionality is framed as a satisfaction problem for requirements; while service risk is addressed as an analysis of failure rates. We use a typical logistics example scenario to illustrate the proposed framework.

The analysis of stakeholder requirements is a critical aspect of software engineering. A common way of specifying stakeholder requirements is in terms of a hierarchy of goals whose AND/OR decomposition captures a family of software solutions that comply with the goals. In this paper, we extend this goal modeling framework to include the specification of optional user requirements and user preferences, aggregated together into weighted formulae to be optimized. We team this with an automated reasoning tool, adapted from state of the art research in artificial intelligence planning with preferences, in order to synthesize solutions that both comply with the goals and optimize stakeholder preferences and optional requirements.

High variability software systems can deliver their functionalities in multiple ways by reconfiguring their components. High variability has become important because of current trends towards software systems that come in product families, offer high levels of personalization, and fit well within a service-oriented architecture. The purpose of our research is to propose a framework that exploits such variability to allow a software system to self-repair in cases of failure. We propose an autonomic architecture that consists of monitoring, diagnosis, reconfiguration and execution components. This architecture uses requirements models as a basis for monitoring, diagnosis, and reconfiguration. We illustrate our proposal with a medium-sized publicly available case study (an automated teller machine (ATM) simulation), and evaluate its performance through a series of experiments. Our experimental results demonstrate that it is feasible to scale our approach to software systems with medium-size requirements.

A requirements engineering artifact is valid relative to the stakeholders of the system-to-be if they agree on the content of that artifact. Checking relative validity involves a discussion between the stakeholders and the requirements engineer. This paper proposes (I) a language for the representation of information exchanged in a discussion about the relative validity of an artifact; (ii) the acceptability condition, which, when it verifies in a discussion captured in the proposed language, signals that the relative validity holds for the discussed artifact and for the participants in the discussion; and (iii) reasoning procedures to automatically check the acceptability condition in a discussions captured by the proposed language.

The increasing complexity of software systems and growing demand for regulations compliance require effective methods and tools to support requirements analysts activities. Internationalization of information systems due to both economics and Web based architectures call for the application of regulations written in different languages. Thus far existing approaches for extracting rights and obligations have concentrated on English documents. In this paper, we describe the results of the application of Cerno, a lightweight framework for semantic annotation, to legal documents written in Italian. In addition, we investigate critical issues for semantic annotation tools in a different cultural and environmental context. Results obtained, while preliminary, allow us to quantify the effort needed to port tools based on Cerno and give some insight on directions of future development of a multilingual system to support semantic annotation of regulations not only in different domains, but also written in different languages.

Traceability links among different software engineering artifacts make explicit how a software system was implemented to accommodate its requirements. For secure and dependable software system development, one must ensure the linked entities are truly traceable to each other and the links are updated to reflect true traceability among changed entities. However, traditional traceability relationships link recovery techniques are not accurate enough. To address this problem, we propose a traceability technique based on refactoring, which is then continuously integrated with other software maintenance activities. Applying our traceability technique to the proven SSL protocol design, we found a significant vulnerability bug in its open-source implementation. The results also demonstrate the level of accuracy and change resilience of our technique that enable reuse of the traceability-related analysis on different implementations.

Software development involves the creation and use of many related models yet there are few tools that address the issue of how to work with and manage such collections of models, or "multimodels." We propose a formal multimodeling framework that allows specialized model relationship types to be defined on existing types of models and provides a new type of model with a formal semantics called a macromodel. Macromodels can be used to enhance multimodel development, comprehension, consistency management and evolution. A preliminary evaluation of the framework is done using a detailed example from the telecommunications domain.

Requirements models are essential not just during system implementation, but also to manage system changes post-implementation. Such models should be supported by a requirements model management framework that allows users to create, manage and evolve models of domains, requirements, code and other design-time artifacts along with traceability links between their elements. We propose a comprehensive framework which delineates the operations and elements necessary, and then describe a tool implementation which supports versioning goal models.

In their seminal paper in the ACM Transactions on Software Engineering and Methodology, Zave and Jackson established a core ontology for requirements engineering (RE) and used it to formulate the "requirements problem", thereby defining what it means to successfully complete RE. Given that stakeholders of the system-to-be communicate the information needed to perform RE, we show that Zave and Jackson's ontology is incomplete. It does not cover all types of basic concerns that the stakeholders communicate. These include beliefs, desires, intentions, and attitudes. In response, we propose a core ontology that covers these concerns and is grounded in sound conceptual foundations resting on a foundational ontology. The new core ontology for RE leads to a new formulation of the requirements problem that extends Zave and Jackson's formulation. We thereby establish new standards for what minimum information should be represented in RE languages and new criteria for determining whether RE has been successfully completed.

In many applications it is important to find a meaningful relationship between the schemas of a source and target database. This relationship is expressed in terms of declarative logical expressions called schema mappings. The more successful previous solutions have relied on inputs such as simple element correspondences between schemas in addition to local schema constraints such as keys and referential integrity. In this paper, we investigate the use of an alternate source of information about schemas, namely the presumed presence of semantics for each table, expressed in terms of a conceptual model (CM) associated with it. Our approach first compiles each CM into a graph and represents each table's semantics as a subtree in it. We then develop algorithms for discovering subgraphs that are plausible connections between those concepts/nodes in the CM graph that have attributes participating in element correspondences. A conceptual mapping candidate is now a pair of source and target subgraphs which are semantically similar. At the end, these are converted to expressions at the database level. We offer experimental results demonstrating that, for test cases of non-trivial mapping expressions involving schemas from a number of domains, the "semantic" approach outperforms the traditional technique in terms of recall and especially precision.

Security, privacy and governance are increasingly the focus of government regulations in the U.S., Europe and elsewhere. This trendhas created a "regulation compliance problem", whereby companiesand developers are required to ensure that their software complies with relevant regulations, either through design or reengineering. We previously proposed a methodology for extracting stakeholder requirements, called rights and obligations, from regulations. In this paper, we examine the challenges of developing tool support for this process. We apply the Cerno framework for textual semantic annotation to propose a tool for semi-automatic semantic annotation of concepts that constitute sources of requirements

Monitoring the satisfaction of software requirements and diagnosing what went wrong in case of failure is a hard problem that has received little attention in the Software and Requirement Engineering literature. To address this problem, we propose a framework adapted from artificial intelligence theories of action and diagnosis. Specifically, the framework monitors the satisfaction of software requirements and generates log data at a level of granularity that can be tuned adaptively at runtime depending on monitored feedback. When errors are found, the framework diagnoses the denial of the requirements and identifies problematic components. To support diagnostic reasoning, we transform the diagnostic problem into apropositional satisfiability (SAT) problem that can be solved by existing SAT solvers. We preprocess log data into a compact propositional encoding that better scales with problem size. The proposed theoretical framework has been implemented as a diagnosing component that will return sound and complete diagnoses accounting for observed aberrant system behaviors. Our solution is illustrated with two medium-sized publicly available case studies: a Web-based email client and an ATM simulation. Our experimental results demonstrate the feasibility of scaling our approach to medium-size software systems

We present details of a goal-oriented process for database requirements analysis. This process consists of a number of steps, spanning the spectrum from high-level stakeholder goal analysis to detailed conceptual schema design. The paper shows how goal modeling contributes to systematic scoping and analysis of the application domain, and subsequent formal specification of database requirements based on this domain analysis. Moreover, a goal-oriented design strategy is proposed to structure the transformation from the domain model to the conceptual schema, according to a set of user defined design issues, also modeled as goals. The proposed process is illustrated step-by-step using a running example from the design of a real-world, industrial biological database. We also report early progress towards building full tool support, by presenting a prototype that captures and stores design sessions in a queryable form. This facility makes it possible to answer questions that are hard, if not impossible, to answer using existing methodologies for database design.

Balance Sheets and Annual Financial Reports play a major role in determining the public worth of any company. In the wake of corporate scandals such as Enron and WorldCom, the US and other countries passed legislation governing reporting processes. The Sarbanes Oxley Act of 2002 (hereafter SOX) requires US national securities exchange and US national security associations not to list any securities of any issuer that is not in compliance with the act. In this paper, we present a business process-based solution to the SOX compliance problem and offer evidence that such a solution is feasible through an industrial case study. The proposed solution aims to support SOX reporting requirements based on core business processes and a continuous improvement of the company's adopted business processes. This means that the solution integrates SOX-related tasks into the "daily work" of a company, rather than achieve compliance on a project basis.

Aspects promote a clear separation of concerns so that tangled and scattered concerns are modularized throughout software development. We propose a framework to trace aspects identified during goal-oriented requirements analysis to code and testing. Two types of checks are performed to validate the resulting system in light of stakeholders' crosscutting concerns. One ensures that systems with and without aspects have the same functionality defined by the hard goals. The other checks whether the weaved system with aspects indeed improves system qualities in terms of the degree of softgoal satisfaction. We demonstrate the approach using an open-source e-commerce platform.

We describe a mechanism based on distributed Event-Condition-Action (ECA) rules that supports data coordination in a multidatabase setting. The proposed mechanism includes an ECA rule language and a rule execution engine that transforms rules when they are first posted, and then coordinates their execution. Like traditional ECA rules, our ECA rule language has three parts: an event language, a condition language, and an action language. The event language provides a set of operators with a formal semantics for a multidatabase environment, and which allows a wide variety of composite events. The condition language provides Boolean algebra operators that take as operands either composite or simple conditions. The action language provides a conjunction of simple or composite actions. The execution model partitions rules to more easily manageable forms, distributes them to relevant databases, monitors their execution and composes their evaluations. The mechanism has been designed in a manner that minimizes the number of messages that need to be exchanged over the network. We have also conducted an experimental evaluation to compare the implementation with a naïve centralized execution model. The paper also presents a prototype implementation as well as experimental results on its performance. This work is part of an on-going project intended to develop data coordination techniques for data sharing settings.

Privacy protection is a growing concern in the marketplace. Yet, privacy requirements and mechanisms are usually retro-fitted into a pre-existing design which may not be able to accommodate them due to potential conflicts with functional requirements. We propose a procedure for automatically extracting privacy requirements from databases supporting access control mechanisms for personal data (hereafter Hippocratic databases) and representing them in the Secure Tropos framework where tools are available for checking the correctness and consistency of privacy requirements. The procedure is illustrated with a case study.

Many classes of distributed applications, including e-business, e-government, and ambient intelligence, consist of networking infrastructures, where the nodes (peers)—be they software components, human actors or organizational units—cooperate with each other to achieve shared goals. The multi-agent system metaphor fits very well such settings because it is founded on intentional and social concepts and mechanisms. Not surprisingly, many agent-oriented software development methods have been proposed, including GAIA, PASSI, and Tropos . This paper extends the Tropos methodology, enhancing its ability to support high variability design through the explicit modelling of alternatives, it adopts an extended notion of agent capability and proposes a refined Tropos design process. The paper also presents an implemented software development environment for Tropos , founded on the Model-Driven Architecture (MDA) framework and standards. The extended Tropos development process is illustrated through a case study involving an e-commerce application.

Design for security is extremely complicated due to the unique nature of the issue. It requires a thorough understanding about the social setting of the security system. To obtain such understanding, sensible steps to take include identifying the players involved in the system, recognizing their personal preferences, agenda and power in relation to other players, identifying the assets being protected, the vulnerable points at which the systems may fail when attacked. Equally important is to taking rationale steps to predict most likely attackers, knowing their possible motivations, and capabilities enabled by latest the technologies and resource occupations. Only based on integrated analysis on both sides, rationale, informative and efficient tradeoffs on security can be made. Unfortunately, current system development practices treat design decisions on security in an ad-hoc way, often as an afterthought. This paper proposes to use social modeling concepts to analyze the business and organizational context of systems with regard to security. The main concepts used are actor, role, agent and goal, task, and resource dependencies between actors. The approach encompasses several analysis steps on the functional and non-functional requirements in relevance to security, thus integrating security into the system design process from the outset

Current ICT application domains, such as Web services and autonomic computing, call for highly flexible systems, capable of adapting to changing operational environments as well as to user needs. Multi-agent system framework do include mechanisms that make flexibility and adaptability possible. In our research we focus on how to take into account environmental constraints and stakeholder needs in the design of software agent capabilities

This poster outlines a set of rules to systematically identify crosscutting concerns present in i* models, and modularizing them using aspects. The result is the reduction of the complexity of those models

Understanding and supporting the interaction between software requirements and architectures remains one of the challenging problems in software engineering research. Our aim is to be able to derive architectural models in concert with multi-agent system requirements specifications. In this paper we present an approach to derive multi-agent systems architecture from requirements using social analysis methods. It is based on two complementary models (organisational model and assignment model) that separate the requirements of the social organisation from those of the software system architecture. A process is defined to provide a systematic way to assist the transition from requirements models to an architectural configuration

System vulnerabilities are often caused by the presence of conflicts within the organization where the system-to-be would eventually operate. In particular, conflicts of interest are very harmful since actors can exploit their positions/roles relative to the system for gaining personal advantage. Capturing and resolving such conflicts is a necessary condition for developing secure information systems. In this paper, we show how conflicts of interest can be formally detected during requirements analysis. This allows system designers to investigate the causes for which conflicts may occur in an organization. Thereby, they can better understand the organizational structure and so provide appropriate countermeasures to resolve or at least mitigate them

We present a case study of a real-world industrial application which produced several versions of conceptual schema design for a biological database during its evolution. We apply the techniques of early requirements analysis to produce a goal model of the problem domain. We then show that by incorporating goal analysis in the design process we can account for the original schemas by tracing them back to stakeholder goals. Moreover, the goal-oriented analysis supports the systematic examination of the space of design alternatives, and better explains what the output of the design process (a conceptual schema) really means. Our results advocate the need for an extended design methodology for databases driven by stakeholder goals

We introduce a variability-intensive approach to goal decomposition that is tailored to support requirements identification for highly customizable software. The approach is based on the semantic characterization of OR-decompositions of goals. We first show that each high-level goal can be associated with a set of concerns, in response to which, alternative refinements of the goal can be introduced. A text corpus relevant to the domain of discourse can be used to derive such variability concerns that are specific to the problem. In parallel, contextual facts that can vary while a goal is being fulfilled are modeled. Then, a high-variability goal model is constructed aiming at responding to the predefined variability concerns completely, while contextual factors are used to test whether it addresses all realistic background circumstances. We apply our approach in a study from the geriatric health care domain

The last fifteen years have seen the rise of a new phase in software development which is concerned with the acquisition, modelling and analysis of stakeholder purposes ("goals") in order to derive functional and nonfunctional requirements. The history of ideas and research results for this new phase was reviewed in a RE'04 keynote presentation by Axel van Lamsweerde. We revisit the topic and sketch on-going research on a number of fronts. Specifically, we discuss an agent-oriented software development methodology -- called Tropos -- that is founded on the concepts of goal, actor as well as inter-actor dependencies. We also show how goal models that characterize a space of possible solutions for meeting stakeholder goals can be used as a basis for designing high variability software. In addition, we report on early work to extend database design techniques to support the generation of a database conceptual schema from stakeholder goals. The research reported is the result of collaborations with colleagues at the Universities of Toronto and Trento.

The rise of a new phase in software development is concerned with the acquisition, modelling and analysis of stakeholder purposes ("goals") in order to derive functional and non-functional requirements. We review the history of ideas and research results for this new phase and sketch on-going research on the topic. Specifically, we discuss an agent-oriented software development methodology - called Tropos - that is founded on the concepts of goal, actor as well as inter-actor dependencies. We also show how goal models that characterize a space of possible solutions for meeting stakeholder goals can be used as a basis for designing high variability software.

Modern information systems often store data that has been transformed and integrated from a variety of sources. This integration may obscure the original source semantics of data items. For many tasks, it is important to be able to determine not only where data items originated, but also why they appear in the integration as they do and through what transformation they were derived. This problem is known as data provenance. In this work, we consider data provenance at the schema and mapping level. In particular, we consider how to answer questions such as "what schema elements in the source(s) contributed to this value", or "through what transformations or mappings was this value derived?" Towards this end, we elevate schemas and mappings to first-class citizens that are stored in a repository and are associated with the actual data values. An extended query language, called MXQL, is also developed that allows meta-data to be queried as regular data and we describe its implementation scenario.

Understanding software engineering issues for autonomic computing systems is critical for the software and information technology sectors, which are continually challenged to reduce the complexity of their systems. To be autonomic, a system must know itself as well as its boundaries and its environment, configure and reconfigure itself, continually optimize itself, recover or heal from malfunction, protect itself, and function in a heterogeneous world-while keeping its complexity hidden from the user. The goal of this workshop is to bring together researchers and practitioners, who investigate concepts, methodologies, techniques, technologies, and tools to design and evolve autonomic software.

Commercial software release management is primarily concerned with the timely release of the next version of a product. There are a number of objectives in any new release of software, including: implementation of new features, repair of known defects, and maintenance of the overall quality of the software to facilitate future evolution. Deciding on the degree to which each of these objectives will be met is a chronic problem, with real-time consequences for managers responsible for software releases. To make effective decisions, management requires supporting product facts and data. This paper presents an approach based on data warehousing technologies for creating, maintaining, accessing and analyzing product data. The result is a tool that provides management with a uniform, integrated presentation of timely information to support decision making. The infrastructure has been evaluated in a large case study, which makes clear the advantages and shortcomings of the approach.

Large-scale legacy programs take long time to compile, thereby hampering productivity. This paper presents algorithms that reduce compilation time by analyzing syntactic dependencies in fine-grain program units, and by removing redundancies as well as false dependencies. These algorithms are combined with parallel compilation techniques (compiler farms, compiler caches), to further reduce build time. We demonstrate through experiments their effectiveness in achieving significant speedup for both fresh and incremental builds.

Security requirements engineering is emerging as a branch of software engineering, spurred by the realization that security must be dealt with early on during the requirements phase. Methodologies in this field are challenging, as they must take into account subtle notions such as trust (or lack thereof), delegation, and permission; they must also model entire organizations and not only systems-to-be. In our previous work we introduced Secure Tropos, a formal framework for modeling and analyzing security requirements. Secure Tropos is founded on three main notions: ownership, trust, and delegation. In this paper, we refine Secure Tropos introducing the notions of at-least delegation and trust of execution; also, at-most delegation and trust of permission. We also propose monitoring as a security design pattern intended to overcome the problem of lack of trust between actors. The paper presents a semantic for these notions, and describes an implemented formal reasoning tool based on Datalog.

Security requirements engineering is emerging as a branch of software engineering, spurred by the realization that security must be dealt with early on during the requirements phase. We propose ST-tool, a CASE tool developed for modeling and analyzing functional and security requirements.

A reverse engineering process aims at reconstructing high-level abstractions from source code. This paper presents a novel reverse engineering methodology for recovering stakeholder goal models from both structured and unstructured legacy code. The methodology consists of the following major steps: 1) Refactoring source code by extracting methods based on comments; 2) Converting the refactored code into an abstract structured program through statechart refactoring and hammock graph construction; 3) Extracting a goal model from the structured program's abstract syntax tree; 4) Identifying nonfunctional requirements and derive soft goals based on the traceability between the code and the goal model. To illustrate this requirements recovery process, we refactor stakeholder goal models from two legacy software code bases: an unstructured Web-based email in PHP (SquirrelMail) and a structured email client system in Java (Columba).

In name and in practice, the World-Wide Web (hereafter Web) is used around the World beyond English-speaking areas. This creates a tremendous need to internationalize standard terminology used in the technologies that make the Web possible. Existing efforts on XML internationalization (i18n) and localization (i10n) have focused on the content of XML documents instead of the terms used in markup (annotations) such as elements and attributes. The SGML standard ISO 8879 supports the use of Unicode (ISO 10646) throughout a document, including markups. However, most elements and attributes of XML documents are still defined in English, thereby limiting their use among non-English speakers. This paper presents an XSLT-based method that can completely localize the markup of XML documents into different natural languages. We also describe how the proposed technique can be applied to translation problems in programming (e.g. C and Java) or documentation (e.g. LATEX or other formatting languages) so that a program or a document can be converted to and from an XML format. Copyright © 2004 John Wiley & Sons, Ltd.

We demonstrate the Toronto Mapping Adaptation System (ToMAS), a tool for automatically detecting and adapting mappings that have become invalid or inconsistent due to changes in either data semantics or schemas. Due to its modular architecture and its stand-alone nature, ToMAS can easily be applied to numerous scenarios and can interoperate with many other tools. To the best of our knowledge, no other tool can correctly maintain the consistency of the mappings under schema changes at the level of complexity supported by ToMAS.

We propose a methodology for designing Web services. The methodology is founded on Tropos (Perini et al., 2001 and Castro, et al., 2002), an agent-oriented software development technique, and supports early and late requirements analysis, as well as architectural and detailed design. An online retailer example is used for illustration of the proposed methodology. We also compare the generated design with a sample design presented in [BPT01].

Enterprise JavaBean (hereafter EJB) technology has been widely adopted in software industry to develop Web information systems. However, most of EJB applications are reengineered from legacy database applications. This means that legacy SQL statements need to be translated into EJB client code. Since many methods in Enterprise Beans can be regarded as view definitions of the underlying database, the EJB client code generation can be mapped to the problem of query rewriting using views. This paper addresses the automatic generation of EJB client code using query rewriting.

Formal Tropos is a specification language for early requirements. It is based on concepts from an agent-oriented early requirement model framework (i/sup */) and extends them with a rich temporal specification language. We demonstrated through a small case study how model checking could be used to verify early requirements written in Formal Tropos. We address issues of methodology and scalability for our earlier proposal. In particular, we propose guidelines for producing a Formal Tropos specification from an i/sup */ diagram and for deciding what model checking technique to use when a particular formal property is to be validated. We also evaluate the scope and scalability of our proposal using a tool, the T-Tool, that maps Formal Tropos specifications to a language that can be handled by NUSMV, a state-of-the-art model checker. Our experiments are based on a course management case study.

Software customization has been argued to benefit both the productivity of software engineers and end users. However, most customization methods rely on specialists to manually tweak individual applications for a specific user group. Existing software development methods also fail to acknowledge the importance of different kinds of user skills and preferences and how these might be incorporated into a customizable software design. We propose a framework for performing requirements analysis on user goals, skills, and preferences in order to generate a customizable software design. We illustrate our methodology with an email system and review an on-going case study involving users with traumatic brain injury.

Security issues for software systems ultimately concern relationships among social actors stakeholders, system users, potential attackers - and the software acting on their behalf. We propose a methodological framework for dealing with security and privacy requirements based on i*, an agent-oriented requirements modeling language. The framework supports a set of analysis techniques. In particular, attacker analysis helps identify potential system abusers and their malicious intents. Dependency vulnerability analysis helps detect vulnerabilities in terms of organizational relationships among stakeholders. Countermeasure analysis supports the dynamic decision-making process of defensive system players in addressing vulnerabilities and threats. Finally, access control analysis bridges the gap between security requirement models and security implementation models. The framework is illustrated with an example involving security and privacy concerns in the design of agent-based health information systems. In addition, we discuss model evaluation techniques, including qualitative goal model analysis and property verification techniques based on model checking.

Task analysis has been used traditionally in HCI and CSCW to define requirements for user interfaces, Web-based or otherwise. This paper argues that a shift of paradigm is needed in Web engineering from task-oriented to goal-oriented approaches for designing applications delivering a quality user experience and achieving the objectives of the stakeholders. Task models focus on fine-grained and precisely defined user needs, thereby risking a commitment to premature design decisions. Moreover, since task analysis focuses on users doing things with the system, tasks do not capture the goals of other stakeholders who are not users. Goal-oriented methods, on the other hand, provide specific support for coping with high-level users' and stakeholders' goals, facilitates the exploration of design alternatives and the definition of requirements at a suitable level of abstraction. As such, goal-based techniques are more suitable for early stages of requirements analysis; task models can be used for later stages, such as detailed interaction design and usability evaluation. The paper conducts a detailed comparison of task and goal-analysis design techniques, using an ongoing project for a museum Web site to illustrate the two techniques and their relative strengths.

Semantic web services are web services with associated semantic descriptions. These descriptions will make it possible for other programs to select, compose and monitor web services at run-time, thereby contributing to the realization of the Semantic Web vision. Researchers have already been active in making the notion of semantic web service more concrete through usage scenaria and technologies that will support their design and use (e.g., [1]). Software Engineering has grappled with the problem of software design for more than three decades. There is welldocumented evidence that designing software manually is a laborious and error-prone task. Semantic descriptions of software (e.g., requirements and design specifications), developed and used at design-time, can facilitate the process of software construction, but they are not panacea. With semantic web services, we seem to be trying to solve the same software development problem, but now these semantic descriptions are used (for selection, composition, monitoring and other purposes) at run-time, automatically. Can we ever hope to see semantic web service technologies and methodologies that actually work? The discussion will focus on this central theme; it will be structured according to the following questions:

Information systems for organizations such as e-business and knowledge management systems must continually evolve to adapt to their operational environment. Unfortunately, current development methodologies do not support system evolution well, making software an obstacle to organizational changes. The paper describes a framework that develops and evolves seamlessly a system-to-be within its organizational environment. We adopt a set of social structures --- organizational styles and social patterns --- based on concepts of organization theory and agent approaches, as a foundation to model early and late requirements as well as architectural and detailed design. We illustrate the use of the social structures through a case study, and we specify one of the styles in Formal Tropos language. This research has been conducted within the context of the Tropos project.

Organizations are changing at an ever-faster pace, as they try to keep up with globalization and the information revolution. Unfortunately, information systems technologies do not support system evolution well, making information systems a roadblock to organizational change. We propose to view information systems as social structures and define methodologies which develop and evolve seamlessly an information system within its operational environment. To this end, this paper proposes an ontology for information systems that is inspired by social and organizational structures. The ontology adopts components of the i* organizational modeling framework, which is founded on the notions of actor, goal and social dependency. Social patterns, drawn from research on cooperative and distributed architectures, offer a more macroscopic level of social structure description. Finally, the proposed ontology includes organizational styles inspired from organization theory. These are used not only to model the overall organizational context of an information system, but also its architecture. Social patterns and organizational styles are defined in terms of configurations of i* concepts. The research has been conducted in the context of the Tropos project.

In recent years we have observed a growing influence of the object-oriented paradigm. Unfortunately, the current dominant object oriented modeling technique, i.e. the Unified Modeling Language, UML, is ill equipped for modeling early requirements which are typically informal and often focus on stakeholder objectives. Instead, UML is suitable for later phases of requirement capture which usually focus on completeness, consistency, and automated verification of functional requirements for the new system. We present a set of guidelines for the integration of early and late requirements specifications. For early (organizational) modeling we rely on the i* framework, whereas for late (functional) requirements specification, we rely on a precise subset of UML. A small example is used to illustrate how the requirements process iterates between early and late requirements.

We describe an attempt to bridge the gap between early requirements specification and formal methods. In particular, we propose a new specification language, called Formal Tropos, that is founded on the primitive concepts of early requirements frameworks (actor, goal, strategic dependency) (Yu, 1997), but supplements them with a rich temporal specification language. We also extend existing formal analysis techniques, in particular model checking, to allow for an automatic verification of relevant properties for an early requirements specification. Our preliminary experiments demonstrate that formal analysis reveals gaps and inconsistencies in early requirements that are by no means trivial to discover without the help of formal analysis tools.

We explore the use of a semantic model to support a group of strategic business analysts in their daily work. In particular, we present a set of modeling constructs for representing goals, events and actors that are relevant to the work of analysts. We also describe a qualitative goal analysis procedure which makes it possible to reason about a goal model under different assumptions. The paper also reports on an incremental document classification scheme that can be used to classify relevant documents with respect to the concepts constituting the semantic model.

As Web technology spreads, the number, variety, and sophistication of Web based information services is literally exploding. While some effort has been put into managing a single, centrally controlled Web site, current Web technologies offer little help for managing Web based applications in-the-large. This is partly due to the distributed, heterogeneous, and open nature of such applications. The paper proposes a generic framework for managing Web based applications which addresses both semantic and managerial issues. Semantic issues are addressed through the inclusion of a domain model component in the framework which describes the kinds of information that are available. Management issues are treated through a framework which includes formally defined notions for an information model, information base consistency, transactions, and concurrency control. Thus, the proposed management system provides a semantically robust environment for Web based information services while allowing for Web source independence.

The large quantity and often questionable quality of available information in the information age provides a shaky foundation for decision making by individuals and organizations alike. This has created a tremendous demand for information services which can access, filter, process and present information on an as-needed basis. However, two factors complicate the design of such information services, namely the distributed and the autonomous nature of data sources. This paper reports on the design and implementation of a generic architecture for supporting information services, which meets the above challenge. The architecture adopts concepts from conceptual modeling to offer a transparent description of the information sources' setting and uses active databases techniques to offer a declarative, event-based language for defining coordination rules for integrating distributed information services. Accordingly, the proposed architecture supports two of the most prominent utilities of information services, namely the pre-designed flow of operations and the reactive provision of information. In addition to describing the architecture and illustrating its features with an example, the paper presents a prototype implementation and reports on some experimental performance results.

The World Wide Web serves as a leading vehicle for information dissemination by offering information services, such as product information, group interactions, or sales transactions. Three major factors affect the performance and reliability of information services for the Web, namely the distribution of information which has resulted from the globalization of information systems, the heterogeneity of information sources, and the sources' instability caused by autonomous evolution. This paper focuses on integrating existing information sources, available via the Web, in the delivery of information services. The primary objective of the paper is to provide mechanisms for structuring and maintaining domain models for Web applications. These mechanisms are based on conceptual modeling techniques, where concepts are being defined and refined within a metadata repository through the use of instantiation, specialization and attribution. Also, active databases techniques are exploited to provide robust mechanisms for maintaining a consistent domain model in a rapidly evolving environment, such as the Web. Therefore, the main contribution of the paper lies in the provision of an architecture for semi-automatic generation and maintenance of user-oriented, semantic-based domain models that describe distributed heterogeneous information sources.

The World Wide Web is serving as a leading vehicle for information dissemination by offering information services, such as product information, group interactions, or sales transactions. Three major factors affect the performance and reliability of information services for the Web: the distribution of information which has resulted from the globalization of information systems, the heterogeneity of information sources, and the sources' instability caused by their autonomous evolution. This paper focuses on integrating existing information sources, available via the Web, in the delivery of information services. The primary objective of the paper is to provide mechanisms for structuring and maintaining a domain model for Web applications. These mechanisms are based on conceptual modeling techniques, where concepts are being defined and refined within a meta-data repository through the use of instantiation, generalization and attribution. Also, active databases techniques are exploited to provide robust mechanisms for maintaining a consistent domain model in a rapidly evolving environment, such as the Web.

In the late '70s, while second generation DBMS products and technologies were entering the market, there was significant research activity whose aim was to make greater use of semantic information in database systems. The focus of that research was primarily on semantic data models and data modelling, including semantic query processing and integrity checking. However, few if any of the results of these efforts found their way in database technologies of the day, or database management practices. Instead, semantic issues were delegated to early phases of information system development (including requirements analysis and design), as well as application development.

Cooperative information systems consist of existing legacy systems integrated in terms of a generic architecture which supports data integration and coordination among the integrated components. The paper presents a proposal for a generic integration architecture named CoopWARE. The architecture is presented in terms of the mechanisms it provides for data integration, and coordination. Data integration is supported by an information repository with an extensible schema, while coordination is facilitated by a rule set and an event-driven rule execution mechanism. In addition, the paper describes implementation and application experiences for the architecture in the context of a three year software engineering project.

Goals and content: The tutorial proposes a generic architecture for cooperative information systems which consists of four layers: the system layer which includes legacy systems, a system integration layer, a human cooperation layer, and an organizational layer. For each, the tutorial will review fundamental concepts, promising research directions, and open questions. The concepts will be illustrated with detailed case studies from production and service industries and with results from ongoing research efforts.

As information systems are increasingly expected to work with humans cooperatively in complex organizational contexts, conceptual modelling techniques need to be extended to relate information structures and processes to business and organizational objectives. We propose a framework which focuses on the modelling of strategic actor relationships (“A-R”) for a richer conceptual model of business processes in their organizational settings. Organizations are viewed as being made up of social actors who are intentional — have motivations, wants, and beliefs — and strategic — they evaluate their relationships to each other in terms of opportunities and vulnerabilities. The framework supports formal modelling of the network of dependency relationships among actors, and the systematic exploration and assessment of alternative process designs in reengineering. The semantics of the modelling concepts are axiomatically characterized. By embedding the framework in the Telos language, the framework can also potentially serve as an early-requirements phase tool in a comprehensive information system development environment.

The paper provides examples of situations where formal specifications of procedures in the standard pre/postcondition style become lengthy, cumbersome and difficult to change, a problem which is particularly acute in the case of object oriented specifications with inheritance. We identify the problem as the inability to express that a procedure changes only those things it has to, leaving everything else unmodified, and review some attempts at dealing with this "frame problem" in the software specification community. The second part of the paper adapts a recent proposal for a solution to the frame problem in artificial intelligence-the notion of explanation closure axioms-to provide an approach whereby one can state such conditions succinctly and modularly, with the added advantage of having the specifier be reminded of things that she may have omitted saying in procedure specifications. Since this approach is based on standard predicate logic, its semantics are relatively straightforward. The paper also suggests an algorithm which generates syntactically the explanation closure axioms from the pre/postcondition specifications, provided they are written in a restricted language; it also suggests a model theory supporting it.>

Large knowledge bases that are intended for applications such as CAD, corporate repositories or process control will have to be shared by multiple users. For these systems to scale up, to give acceptable performance and to exhibit consistent behavior, it is mandatory to synchronize user transactions using a concurrency control algorithm. In this paper, we examine a novel concurrency control policy called Dynamic Directed Graph (or DDG) policy that effectively exploits the rich semantic structure of a knowledge base.

The authors discuss the representational requirements for capturing and processing the conceptual knowledge about software descriptions. Software repositories should not only provide the service of managing evolving objects and software-related descriptions in integrated environments. This requires addressing the representational adequacy and semantics of present object management systems. Based on experiences gained in a series of computer-aided software engineering (CASE) integration projects, they point out abstractional, assertional, and dynamic clustering requirements of data modeling language for repository managers. A simple example illustrates how the deductive object management system ConceptBase, embodying Telos as its data model, meets these requirements.>

Describes the implementation of a real-time controller for dexterous manipulation with a hierarchical intelligent control architecture. The architecture is based on a blackboard model that enables incremental, opportunistic, and dynamic decision making and control. The following features have been incorporated into the dexterous robot hand controller: (1) controlling robot fingers using robotic common sense reasoning, based on qualitative representations of control variables and parameters; and (2) opportunistically switching between coarse qualitative control that is based on a physical model and conventional fine quantitative control that is based on a mathematical model. The controller was implemented on a multirobot grasping facility, and preliminary experimental results are presented.>

The power of any information system technology is delimited by the expressiveness of the notation used to represent information. Classification constitutes a fundamental notational structuring mechanism and, not surprisingly, is supported in one form or another by many formal notations intended for data or knowledge modelling. This paper presents an overview of various manifestations of classification mechanisms. Further, characteristic features of classification, such as the form of inheritance allowed from classes to instances, having single or multiple classifications and the structure of the classification hierarchy are identified, discussed, and contrasted. The paper also describes the classification mechanism offered by the knowledge representation language Telos. In Telos, classification is stratified and applicable not only to objects but also to (binary) relationships. The paper argues that these features lead to a more expressive notation, acquired at relatively modest conceptual and computational costs.

We present a framework for the development of information systems based on the premise that the knowledge that influences the development process needs to somehow be captured, represented, and managed if the development process is to be rationalized. Experiences with a prototype environment developed in ESPRIT project DAIDA demonstrate the approach. The project has implemented an environment based on state-of-the-art languages for requirements modeling, design and implementation of information systems. In addition, the environment offers tools for aiding the mapping process from requirements to design and then to implementation, also for representing decisions reached during the development process. The development process itself is represented explicitly within the system, thus making the DAIDA development framework easier to comprehend, use, and modify.

A comprehensive framework for representing and using nonfunctional requirements during the development process is proposed. The framework consists of five basic components which provide the representation of nonfunctional requirements in terms of interrelated goals. Such goals can be refined through refinement methods and can be evaluated in order to determine the degree to which a set of nonfunctional requirements is supported by a particular design. Evidence for the power of the framework is provided through the study of accuracy and performance requirements for information systems.>

We describe Telos, a language intended to support the development of information systems. The design principles for the language are based on the premise that information system development is knowledge intensive and that the primary responsibility of any language intended for the task is to be able to formally represent the relevent knowledge. Accordingly, the proposed language is founded on concepts from knowledge representations. Indeed, the language is appropriate for representing knowledge about a variety of worlds related to a particular information system, such as the subject world (application domain), the usage world (user models, environments), the system world (software requirements, design), and the development world (teams, metodologies). We introduce the features of the language through examples, focusing on those provided for desribing metaconcepts that can then be used to describe knowledge relevant to a particular information system. Telos' fetures include an object-centered framework which supports aggregation, generalization, and classification; a novel treatment of attributes; an explicit representation of time; and facilities for specifying integrity constraints and deductive rules. We review actual applications of the language through further examples, and we sketch a formalization of the language.

The features of a compiler for the Taxis design language are described and discussed. Taxis offers an entity-based framework for designing interactive information systems and supports generalisation, classification and aggregation as abstraction mechanisms. Its features include multiple inheritance of attributes, isA hierarchies of transactions, metaclasses, typed attributes, a procedural exception-handling mechanism and an iteration construct based on the abstraction mechanisms supported Developing a compiler for the language involved dealing with the problems of efficiently representing and accessing a large collection of entities, performing (static) type checking and representing isA hierarchies of transactions.

TAXIS, a language for the design of interactive information systems (e.g., credit card verification, student-course registration, and airline reservations) is described. TAXIS offers (relational) database management facilities, a means of specifying semantic integrity constraints, and an exception-handling mechanism, integrated into a single language through the concepts of class, property , and the IS-A (generalization) relationship . A description of the main constructs of TAXIS is included and their usefulness illustrated with examples.

This paper describes TAXIS, a language for the design of Interactive Information Systems (e.g., credit card varification, student-course registration and airline reservations). TAXIS offers (relational) database management facilities, a means of specifying semantic integrity constraints and an exception-handling mechanism, integrated into a single language through the concepts of class, property and the ISA (generalization) relationship. The paper includes a description of the main constructs of TAXIS and illustrates their usefulness with examples.

This paper presents a semantic model of data bases. The model assumes the availability of a semantic network storing knowledge about a data base and a set of attributes for the data base. The use of the semantic net in generating a relational schema for the data base, in defining a set of semantic operators and in maintaining the data base consistent is then demonstrated.

It is the object of this paper to study the topological properties of finite graphs that can be embedded in the n -dimensional integral lattice (denoted N n ). The basic notion of deletability of a node is first introduced. A node is deletable with respect to a graph if certain computable conditions are satisfied on its neighborhood. An equivalence relation on graphs called reducibility and denoted by “∼” is then defined in terms of deletability, and it is shown that (a) most important topological properties of the graph (homotogy, homology, and cohomology groups) are ∼-invariants; (b) for graphs embedded in N 3 , different knot types belong to different ∼-equivalence classes; (c) it is decidable whether two graphs are reducible to each other in N 2 but this problem is undecidable in N n for n ≥ 4. Finally, it is shown that two different methods of approximating an n -dimensional closed manifold with boundary by a graph of the type studied in this paper lead to graphs whose corresponding homology groups are isomorphic.

An attempt is made to define meaningful counterparts of topological notions in quantized spaces.Finitely presented Abelian groups are used as a model for such spaces.Then the notion of dimension is introduced through a recursive definition and it is proven that for free Abelian groups it equals the number of generators.

A notion of equivalence (c-equivalence) is defined as the counterpart of homeoinorphism for quantized spaces.It is shown that sets with the same number of components and holes are c-equivalent in two-dimensional spaces.Then it is shown that for each arbitrary set there is a set c-equivalent to it with certain "regular" features (rectangular perimeter, holes with diameter one, etc.).