5,119 research outputs found
Mastering the requirements analysis for communication-intensive websites
Web application development still needs to employ effective methods to accommodate some distinctive aspects of the requirements analysis process: capturing high-level communication goals, considering several user profiles and stakeholders, defining hypermedia-specific requirements (concerning navigation, content, information structure and presentation aspects), and reusing requirements for an effective usability evaluation. Techniques should be usable by both stakeholders and the design team, require little training effort, and show relative advantage to project managers. Over the last few years, requirements methodologies applied to web-based applications have considered mainly the transactional and operational aspects typical of traditional information systems. The communicational aspects of web sites have been neglected in regards to systematic requirements methods. This thesis, starting from key achievements in Requirements Engineering (hereafter RE), introduces a model (AWARE) for defining and analyzing requirements for web applications mainly conceived as strategic communication means for an institution or organization. The model extends traditional goal and scenario-based approaches for refining highlevel goals into website requirements, by introducing the analysis of ill-defined user goals, stakeholder communication goals, and a hypermedia requirement taxonomy to facilitate web conceptual design, and paving the way for a systematic usability evaluation. AWARE comprises a conceptual toolkit and a notation for effective requirements documentation. AWARE concepts and notation represent a useful communication and analysis conceptual tool that may support in the elicitation, negotiation, analysis and validation of requirements from the relevant stakeholders (users included). The empirical validation of the model is carried out in two ways. Firstly, the model has been employed in web projects on the field. These case studies and the lessons learnt will be presented and discussed to assess advantages and limits of the proposal. Secondly, a sample of web analysts and designers has been asked to study and apply the model: the feedback gathered is positive and encouraging for further improvement.Lo sviluppo di applicazioni web necessita di strumenti efficaci per gestire alcuni aspetti essenziali del processo di analisi dei requisiti: l'identificazione di obiettivi di comunicazione strategici, la presenza di una varietà di profili utente e di stakeholders, le definizione di requisiti ipermediali (riguardanti navigazione, interazione, contenuto e presentazione), e il riuso dei requisiti per una pianificazione efficace della valutazione dell'usabilità . Sono necessarie tecniche usabili sia dagli stakeholders che dai progettisti, che richiedono un tempo breve per essere appresi ed usati con efficacia, mostrando vantaggi significativi ai gestori di progetti complessi. La tesi definisce AWARE (Analysis of Web Application Requirements) - una metodologia per l'analisi dei requisiti specifica per la gestione di siti web (ed applicazioni interattive) con forti componenti comunicative. La metodologia estende le tecniche esistenti dell''analisi dei requisiti basate su approcci goal-oriented e scenario-based, introducendo una tassonomia di requisiti specifica per siti web (che permette di dare un input strutturato all'attività di progetazione), strumenti per l'identificazione e l'analisi di obiettivi ill-defined (generici o mal-definiti) e di obiettivi comunicativi e supporto metodologico per la valutazione dell'usabilità basata sui requisiti dell'applicazione. La metodologia AWARE è stata valutata sul campo attraverso progetti con professionisti del settore (web designers e IT managers), e grazie ad interventi di formazione in aziende specializzate nella comunicazione su web
Forms of European Administrative Action
Chiti examines the various forms of European administration and their associated administrative law systems. Chiti recounts the history of administration and of administrative law in the European Community, examines the main types of administrative action in the Community, and highlights the novel elements and the shortcomings of European administrative law today
A reuse-Oriented Approach for the Construction of Scenario Bases Methods
International audienceDespite the recent interest in scenarios, the development of new methods and tools for Requirements Engineering integrating scenario based approaches has been limited. This paper reports on four different processes developed from research undertaken as part of the CREWS project which the authors believe will improve scenario use and make it more systematic. Furthermore CREWS aims to integrate these approaches into a method for scenario-based requirements engineering. To achieve this objective and be able to include existing approaches such as use case analysis we develop a component based approach which reflects a shift towards a reuse-centric approach to method engineering. The paper presents CREWS method and meta-method knowledge through the implementation of an SGML database to store, retrieve and dynamically compose chunks of CREWS processes
Towards automated restructuring of object oriented systems
The work introduces a method for diagnosing design flaws in object oriented systems, and finding meaningful refactorings to remove such flaws. The method is based on pairing up a structural pattern that is considered pathological (e.g. a code smell or anti-pattern) with a so called design context. The design context describes the design semantics associated to the pathological structure, and the desired strategic closure for that fragment. The process is tool supported and largely automated
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A framework for defining and analysing access policies in requirements models
Enforcing access policies derived from management control principles is a way by which organisations protect their information assets. The minimum privileges principle is an example of a management control principle, which specifies that users should only have access to resources they require to carry out their duties. Requirements models use actors to specify their access policies. Actors normally represent roles that users adopt, however a role can have different meanings, such as a position in an organisation or the assignment of a task, and can therefore be misleading. Current requirements modelling approaches do not provide a systematic way of defining roles for incorporation into access policies, and therefore we can not ensure that they satisfy management control principles. In this thesis we address the need to provide precise role definitions by developing a framework that facilitates the derivation of roles from the organisational context. The framework consists of a metamodel, which enables the organisational context to be represented and related to actors; a set of heuristics for deriving the organisational context; and a set of language constructs for formulating access policies, and verifying them using scenarios.
We use the meta-model and language constructs that we developed to extend an existing requirements modelling language, the i* framework, and in particular a formal version of it, formal Tropos, to define and verify access policies definitions satisfying the minimum privileges principle. We also investigate the use of automated tool checking by translating the formal Tropos definitions into the specification language Alloy, which is supported by a tool that automatically checks assertions, to ensure consistency of the access policy definitions. We carry out a detailed case study taken from the literature to verify the extensions to the i* framework and the tool supported analysis.
The framework presented in this thesis makes a novel contribution to the modelling of access policies as requirements, enabling us to define access policies using actors derived from the organisational context, that satisfy the minimum privileges principle
Modelling and analyzing adaptive self-assembling strategies with Maude
Building adaptive systems with predictable emergent behavior is a challenging task and it is becoming a critical need. The research community has accepted the challenge by introducing approaches of various nature: from software architectures, to programming paradigms, to analysis techniques. We recently proposed a conceptual framework for adaptation centered around the role of control data. In this paper we show that it can be naturally realized in a reflective logical language like Maude by using the Reflective Russian Dolls model. Moreover, we exploit this model to specify, validate and analyse a prominent example of adaptive system: robot swarms equipped with self-assembly strategies. The analysis exploits the statistical model checker PVeStA
MATrA: meta-modelling approach to traceability for avionics
PhD ThesisTraceability is the common term for mechanisms to record and navigate relationships between artifacts
produced by development and assessment processes. Effective management of these relationships is
critical to the success of projects involving the development of complex aerospace products.
Practitioners use a range of notations to model aerospace products (often as part of a defined technique
or methodology). Those appropriate to electrical and electronic systems (avionics) include Use Cases
for requirements, Ada for development and Fault Trees for assessment (others such as PERT networks
support product management). Most notations used within the industry have tool support, although a
lack of well-defined approaches to integration leads to inconsistencies and limits traceability between
their respective data sets (internal models).
Conceptually, the artifacts produced using such notations populate four traceability dimensions. Of
these, three record links between project artifacts (describing the same product), while the fourth relates
artifacts across different projects (and hence products), and across product families within the same
project.
The scope of this thesis is to define a meta-framework that characterises traceability dimensions for
aerospace projects, and then to propose a concrete framework capturing the syntax and semantics of
notations used in developing avionics for such projects which enables traceability across the four
dimensions. The concrete framework is achieved by exporting information from the internal models of
tools supporting these notations to an integrated environment consisting of. i) a Workspace comprising
a set of structures or meta-models (models describing models) expressed in a common modelling
language representing selected notations (including appropriate extensions reflecting the application
domain); ii) well-formedness constraints over these structures capturing properties of the notations (and
again, reflecting the domain); and iii) associations between the structures. To maintain consistency and
identify conflicts, elements of the structures are verified against a system model that defines common
building blocks underlying the various notations.
The approach is evaluated by (partial) tool implementation of the structures which are populated using
case study material derived from actual commercial specifications and industry standards
The GOALS approach: business and software modeling traceability by means of human-computer interaction: enterprise modeling language and method
The management of an enterprise relies on the continuous organization and development of its business and software systems. A process that requires merging the ideas of the enterprise’ systems managers, targeting the specification of business requirements and the conception and implementation of a supporting information system. This process finds obstacles in the identification and communication of requirements, and also in their transformation in software artefacts, leading to difficulties or loss of traceability between business and software models. Existing methods, languages and techniques are still not sufficiently standardized to ensure that when a business improvement is introduced, the supportive software solution will be implemented within budget and time. Methods are still too closed to the concepts of their original scientific domains, conceiving solutions which are not representative of the business and software conceptual relation and of the complexity concealed in an improvement effort, namely concerning usability and user experience. Moreover, the lack of a common modeling language and method for the conception of holistic and traceable software solutions, also refrains the performance of the enterprise development process. The GOALS Approach presents a solution to surpass these barriers by means of the specification of an enterprise modeling language that relates the business and software conceptual structures using a shared set of concepts, a notation, process, method and techniques, that allow the design of the software as a result of the business organization, ensuring traceability by means of the permanent representation of the business structure in the software structure
Programming and Proving with Distributed Protocols
Distributed systems play a crucial role in modern infrastructure, but are notoriously difficult to
implement correctly. This difficulty arises from two main challenges: (a) correctly implementing
core system components (e.g., two-phase commit), so all their internal invariants hold, and (b)
correctly composing standalone system components into functioning trustworthy applications (e.g.,
persistent storage built on top of a two-phase commit instance). Recent work has developed several
approaches for addressing (a) by means of mechanically verifying implementations of core distributed
components, but no methodology exists to address (b) by composing such verified components into
larger verified applications. As a result, expensive verification efforts for key system components are
not easily reusable, which hinders further verification efforts.
In this paper, we present Disel, the first framework for implementation and compositional
verification of distributed systems and their clients, all within the mechanized, foundational context
of the Coq proof assistant. In Disel, users implement distributed systems using a domain specific
language shallowly embedded in Coq and providing both high-level programming constructs as well
as low-level communication primitives. Components of composite systems are specified in Disel as
protocols, which capture system-specific logic and disentangle system definitions from implementation
details. By virtue of Disel’s dependent type system, well-typed implementations always satisfy
their protocols’ invariants and never go wrong, allowing users to verify system implementations
interactively using Disel’s Hoare-style program logic, which extends state-of-the-art techniques for
concurrency verification to the distributed setting. By virtue of the substitution principle and frame
rule provided by Disel’s logic, system components can be composed leading to modular, reusable
verified distributed systems.
We describe Disel, illustrate its use with a series of examples, outline its logic and metatheory,
and report on our experience using it as a framework for implementing, specifying, and verifying
distributed systems
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