Software development by abstract behavioural specification

The development process of any software has become extremely important not just in the IT industry, but in almost every business or domain of research. The effort in making this process quick, efficient, reliable and automated has constantly evolved into a flow that delivers software incrementally based on both the developer's best skills and the end user's feedback. Software modeling and modeling languages have the purpose of facilitating product development by designing correct and reliable applications. The concurrency model of the Abstract Behavioural Specification (ABS) Language with features for asynchronous programming and cooperative scheduling is an important example of how modeling contributes to the reliability and robustness of a product. By abstracting from the implementation details, program complexity and inner workings of libraries, software modeling, and specifically ABS, allow for an easier use of formal analysis techniques and proofs to support product design. However there is still a gap that exists between modeling languages and programming languages with the process of software development often going on two separate paths with respect to modeling and implementation. This potentially introduces errors and doubles the development effort. \par The overall objective of this research is bridging the gap between modeling and programming in order to provide a smooth integration between formal methods and two of the most well-known and used languages for software development, the Java and Scala languages. The research focuses mainly on sequential and highly parallelizable applications, but part of the research also involves some theoretical proposals for distributed systems. It is a first step towards having a programming language with support for formal models. Algorithms and the Foundations of Software technolog

Model Driven Development and Maintenance of Business Logic for Information Systems

Since information systems become more and more important in today\''s society, business firms, organizations, and individuals rely on these systems to manage their daily business and social activities. The dependency of possibly critical business processes on complex IT systems requires a strategy that supports IT departments in reducing the time needed to implement changed or new domain requirements of functional departments. In this context, software models help to manage system\''s complexity and provide a tool for communication and documentation purposes. Moreover, software engineers tend to use automated software model processing such as code generation to improve development and maintenance processes. Particularly in the context of web-based information systems, a number of model driven approaches were developed. However, we believe that compared to the user interface layer and the persistency layer, there could be a better support of consistent approaches providing a suitable architecture for the consistent model driven development of business logic. To ameliorate this situation, we developed an architectural blueprint consisting of meta models, tools, and a method support for model driven development and maintenance of business logic from analysis until system maintenance. This blueprint, which we call Amabulo infrastructure, consists of five layers and provides concepts and tools to set up and apply concrete infrastructures for model driven development projects. Modeling languages can be applied as needed. In this thesis we focus on business logic layers of J2EE applications. However, concrete code generation rules can be adapted easily for different target platforms. After providing a high-level overview of our Amabulo infrastructure, we describe its layers in detail: The Visual Model Layer is responsible for all visual modeling tasks. For this purpose, we discuss requirements for visual software models for business logic, analyze several visual modeling languages concerning their usefulness, and provide an UML profile for business logic models. The Abstract Model Layer provides an abstract view on the business logic model in the form of a domain specific model, which we call Amabulo model. An Amabulo model is reduced to pure logical information concerning business logic aspects. It focuses on information that is relevant for the code generation. For this purpose, an Amabulo model integrates model elements for process modeling, state modeling, and structural modeling. It is used as a common interface between visual modeling languages and code generators. Visual models of the Visual Model Layer are automatically transformed into an Amabulo model. The Abstract System Layer provides a formal view onto the system in the form of a Coloured Petri Net (CPN). A Coloured Petri Net representation of the modeled business logic is a formal structure and independent of the actual business logic implementation. After an Amabulo model is automatically transformed into a CPN, it can be analyzed and simulated before any line of code is generated. The Code Generation Layer is responsible for code generation. To support the design and implementation of project-specific code generators, we discuss several aspects of code integration issues and provide object-oriented design approaches to tackle the issues. Then, we provide a conceptual mapping of Amabulo model elements into architectural elements of a J2EE infrastructure. This mapping explicitly considers robustness features, which support a later manual integration of generated critical code artifacts and external systems. The Application Layer is the target layer of an Amabulo infrastructure and comprises generated code artifacts. These artifacts are instances of a specific target platform specification, and they can be modified for integration purposes with development tools. Through the contributions in this thesis, we aim to provide an integrated set of solutions to support an efficient model driven development and maintenance process for the business logic of information systems. Therefore, we provide a consistent infrastructure blueprint that considers modeling tasks, model analysis tasks, and code generation tasks. As a result, we see potential for reducing the development and maintenance efforts for changed domain requirements and simultaneously guaranteeing robustness and maintainability even after several changes

Non-functional properties in the model-driven development of service-oriented systems

Systems based on the service-oriented architecture (SOA) principles have become an important cornerstone of the development of enterprise-scale software applications. They are characterized by separating functions into distinct software units, called services, which can be published, requested and dynamically combined in the production of business applications. Service-oriented systems (SOSs) promise high flexibility, improved maintainability, and simple re-use of functionality. Achieving these properties requires an understanding not only of the individual artifacts of the system but also their integration. In this context, non-functional aspects play an important role and should be analyzed and modeled as early as possible in the development cycle. In this paper, we discuss modeling of non-functional aspects of service-oriented systems, and the use of these models for analysis and deployment. Our contribution in this paper is threefold. First, we show how services and service compositions may be modeled in UML by using a profile for SOA (UML4SOA) and how non-functional properties of service-oriented systems can be represented using the non-functional extension of UML4SOA (UML4SOA-NFP) and the MARTE profile. This enables modeling of performance, security and reliable messaging. Second, we discuss formal analysis of models which respect this design, in particular we consider performance estimates and reliability analysis using the stochastically timed process algebra PEPA as the underlying analytical engine. Last but not least, our models are the source for the application of deployment mechanisms which comprise model-to-model and model-to-text transformations implemented in the framework VIATRA. All techniques presented in this work are illustrated by a running example from an eUniversity case study

Investigation of a Novel Formal Model for Mobile User Interface Design

Mobile user interfaces are becoming increasingly complex due to the expanding range of functionalities that they incorporate, which poses significant difficulties in software development. Formal methods are beneficial for highly complex software systems, as they enable the designed behaviour of a mobile user interface (UI) to be modelled and tested for accuracy before implementation. Indeed, assessing the compatibility between the software specification and user requirements and verifying the implementation in relation to the specification are essential procedures in the development process of any type of UI. To ensure that UIs meet users‘ requirements and competences, approaches that are based on interaction between humans and computers employ a variety of methods to address key issues. The development of underlying system functionality and UIs benefit from formal methods as well as from user-interface design specifications. Therefore, both approaches are incorporated into the software development process in this thesis. However, this integration is not an easy task due to the discrepancies between the two approaches. It also includes a method, which can be applied for both simple and complex UI applications. To overcome the issue of integrating both approaches, the thesis proposes a new formal model called the Formal Model of Mobile User Interface Design (FMMUID). This model is devised to characterise the composition of the UI design based on hierarchical structure and a set theory language. To determine its applicability and validity, the FMMUID is implemented in two real-world case studies: the quiz game iPlayCode and the social media application Social Communication (SC). A comparative analysis is undertaken between two case studies, where each case study has three existing applications with similar functionality in terms of structure and numbers of elements, functions and colours. Furthermore, the case studies are also assessed from a human viewpoint, which reveals that they possess better usability. The assessment supports the viability of the proposed model as a guiding tool for software development. The efficiency of the proposed model is confirmed by the result that the two case studies are less complex than the other UI applications in terms of hierarchical structure and numbers of elements, functions and colours, whilst also presenting acceptable usability in terms of the four examined dimensions: usefulness, information quality, interface quality, and overall satisfaction. Hence, the proposed model can facilitate the development process of mobile UI applications

A model driven approach for software reliability prediction

Software reliability, one of the major software quality attributes, quantitatively expresses the continuity of correct service delivery. In current practice, reliability models are typically measurement-based models, and mostly employed in isolation at the later stage of the soft ware development process, after architectural decisions have been made that cannot easily be reversed early software reliability prediction models are often insufficiently formal to be ana- lyzable and not usually connected to the target system. We postulate it is possible to overcome these issues by supporting software reliability engineering from requirements to deployment using scenario specifications. We contribute a novel reliability prediction technique that takes into account the component structure exhibited in the scenarios and the concurrent nature of component-based systems by extending scenario specifications to model (1) the probability of component failure, and (2) scenario transition probabilities. Those scenarios are subsequently transformed into enhanced behaviour models to compute the system reliability. Additionally we enable the integration between reliability and development models through profiles that extend the core Unified Modelling Language (UML). By means of a reli ability profile, the architecture of a component-based system can express both method invoca tions and deployment relationships between the application components in one environment. To facilitate reliability prediction, and determine the impact of concurrency on systems reliability, we have extended the Label Transition System Analyser Tool (LTSA), implementing a plugin for reliability analysis. Finally, we evaluate our analysis technique with a case study focusing on Condor, a dis tributed job scheduler and resource management system. The purpose of the case study is to evaluate the efficacy of our analysis technique and to compare it with other reliability tech niques

Boost the Impact of Continuous Formal Verification in Industry

Software model checking has experienced significant progress in the last two decades, however, one of its major bottlenecks for practical applications remains its scalability and adaptability. Here, we describe an approach to integrate software model checking techniques into the DevOps culture by exploiting practices such as continuous integration and regression tests. In particular, our proposed approach looks at the modifications to the software system since its last verification, and submits them to a continuous formal verification process, guided by a set of regression test cases. Our vision is to focus on the developer in order to integrate formal verification techniques into the developer workflow by using their main software development methodologies and tools.Comment: 7 page

Quality-aware model-driven service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Quality aspects ranging from interoperability to maintainability to performance are of central importance for the integration of heterogeneous, distributed service-based systems. Architecture models can substantially influence quality attributes of the implemented software systems. Besides the benefits of explicit architectures on maintainability and reuse, architectural constraints such as styles, reference architectures and architectural patterns can influence observable software properties such as performance. Empirical performance evaluation is a process of measuring and evaluating the performance of implemented software. We present an approach for addressing the quality of services and service-based systems at the model-level in the context of model-driven service engineering. The focus on architecture-level models is a consequence of the black-box character of services

Requirements modelling and formal analysis using graph operations

The increasing complexity of enterprise systems requires a more advanced analysis of the representation of services expected than is currently possible. Consequently, the specification stage, which could be facilitated by formal verification, becomes very important to the system life-cycle. This paper presents a formal modelling approach, which may be used in order to better represent the reality of the system and to verify the awaited or existing system’s properties, taking into account the environmental characteristics. For that, we firstly propose a formalization process based upon properties specification, and secondly we use Conceptual Graphs operations to develop reasoning mechanisms of verifying requirements statements. The graphic visualization of these reasoning enables us to correctly capture the system specifications by making it easier to determine if desired properties hold. It is applied to the field of Enterprise modelling