Quality Goal Oriented Architectural Design and Traceability for Evolvable Software Systems

Softwaresysteme werden heute z.B. aufgrund sich ändernder Geschäftsprozesse oder Technologien mit häufigen Veränderungen konfrontiert. Die Software und speziell ihre Architektur muss diese Änderungen zur dauerhaften Nutzbarkeit ermöglichen.Während der Software-Evolution können Änderungen zu einer Verschlechterung der Architektur führen, der Architekturerosion. Dies erschwert oder verhindert weitere Änderungen wegen Inkonsistenz oder fehlendem Programmverstehen. Zur Erosionsvermeidung müssen Qualitätsziele wie Weiterentwickelbarkeit, Performanz oder Usability sowie die Nachvollziehbarkeit von Architekturentwurfsentscheidungen berücksichtigt werden. Dies wird jedoch oft vernachlässigt.Existierende Entwurfsmethoden unterstützen den Übergang von Qualitätzielen zu geeigneten Architekturlösungen nur unzureichend aufgrund einer Lücke zwischen Methoden des Requirements Engineering und des Architekturentwurfs. Insbesondere gilt dies für Weiterentwickelbarkeit und die Nachvollziehbarkeit von Entwurfsentscheidungen durch explizite Modellabhängigkeiten.Diese Arbeit präsentiert ein neues Konzept, genannt Goal Solution Scheme, das Qualitätsziele über Architekturprinzipien auf Lösungsinstrumente durch explizite Abhängigkeiten abbildet. Es hilft somit, Architekturlösungen entsprechend ihrem Einfluss auf Qualitätsziele auszuwählen. Das Schema wird speziell hinsichtlich Weiterentwickelbarkeit diskutiert und ist in ein zielorientiertes Vorgehen eingebettet, das etablierte Methoden und Konzepte des Requirements Engineering und Architekturentwurfs verbessert und integriert. Dies wird ergänzt durch ein Traceability-Konzept, welches einen regelbasierten Ansatz mit Techniken des Information Retrieval verbindet. Dies ermöglicht eine (halb-) automatische Erstellung von Traceability Links mit spezifischen Linktypen und Attributen für eine reichhaltige Semantik sowie mit hoher Genauigkeit und Trefferquote.Die Realisierbarkeit des Ansatzes wird an einer Fallstudie einer Software für mobile Serviceroboter gezeigt. Das Werkzeug EMFTrace wurde als eine erweiterbare Plattform basierend auf Eclipse-Technologie implementiert, um die Anwendbarkeit der Konzepte zu zeigen. Es integriert Entwurfsmodelle von externen CASE-Tools mittels XML-Technologie in einem gemeinsamen Modell-Repository, wendet Regeln zur Linkerstellung an und bietet Validierungsfunktionen für Regeln und Links.Today software systems are frequently faced with demands for changes, for example, due to changing business processes or technologies. The software and especially its architecture has to cope with those frequent changes to permanently remain usable.During software evolution changes can lead to a deterioration of the structure of software architectures called architectural erosion, which hampers or even inhibits further changes because of inconsistencies or lacking program comprehension. To support changes and avoid erosion, especially quality goals, such as evolvability, performance, or usability, and the traceability of design decisions have to be considered during architectural design. This however often is neglected.Existing design methods do not sufficiently support the transition from the quality goals to appropriate architectural solutions because there is still a gap between requirements engineering and architectural design methods. Particularly support is lacking for the goal evolvability and for the traceability of design decisions by explicit model dependencies.This thesis presents a new concept called Goal Solution Scheme, which provides a mapping from goals via architectural principles to solution instruments by explicit dependencies. Thus it helps to select appropriate architectural solutions according to their influence on quality goals. The scheme is discussed especially regarding evolvability, and it is embedded in a goal-oriented architectural design method, which enhances and integrates established methods and concepts from requirements engineering as well as architectural design. This is supplemented by a traceability concept, which combines a rule-based approach with information retrieval techniques for a (semi-) automated establishment of links with specific link types and attributes for rich semantics and a high precision and recall.The feasibility of the design approach has been evaluated in a case study of a software platform for mobile robots. A prototype tool suite called EMFTrace was implemented as an extensible platform based on Eclipse technology to show the practicability of the thesis' concept. It integrates design models from external CASE tools in a joint model repository by means of XML technology, applies rules for link establishment, and provides validation capabilities for rules and links

NASA space station automation: AI-based technology review. Executive summary

Research and Development projects in automation technology for the Space Station are described. Artificial Intelligence (AI) based technologies are planned to enhance crew safety through reduced need for EVA, increase crew productivity through the reduction of routine operations, increase space station autonomy, and augment space station capability through the use of teleoperation and robotics

Feature-based methodology for supporting architecture refactoring and maintenance of long-life software systems

Zusammenfassung Langlebige Software-Systeme durchlaufen viele bedeutende Veraenderungen im Laufe ihres Lebenszyklus, um der Weiterentwicklung der Problemdomaenen zu folgen. Normalerweise ist es schwierig eine Software-Systemarchitektur den schnellen Weiterentwicklungen einer Problemdomaene anzupassen und mit der Zeit wird der Unterschied zwischen der Problemdomaene und der Software-Systemarchitektur zu groß, um weitere Softwareentwicklung sinnvoll fortzufuehren. Fristgerechte Refactorings der Systemarchitektur sind notwendig, um dieses Problem zu vermeiden. Aufgrund des verhaeltnismaeßig hohen Gefahrenpotenzials und des zeitlich stark verzoegerten Nutzens von Refactorings, werden diese Maßnahmen normalerweise bis zum letztmoeglichen Zeitpunkt hinausgeschoben. In der Regel ist das Management abgeneigt Architektur-Refactorings zu akzeptieren, außer diese sind absolut notwendig. Die bevorzugte Vorgehensweise ist, neue Systemmerkmale ad hoc hinzuzufuegen und nach dem Motto ”Aendere nie etwas an einem funktionierenden System!” vorzugehen. Letztlich ist das Ergebnis ein Architekturzerfall (Architekturdrift). Die Notwendigkeit kleiner Refactoring-Schritte fuehrt zur Notwendigkeit des Architektur-Reengineerings. Im Gegensatz zum Refactoring, das eine normale Entwicklungstaetigkeit darstellt, ist Reengineering eine Form der Software- ”Revolution”. Reengineeringprojekte sind sehr riskant und kostspielig. Der Nutzen des Reengineerings ist normalerweise nicht so hoch wie erwartet. Wenn nach dem Reengineering schließlich die erforderlichen Architekturaenderungen statt.nden, kann dies zu spaet sein. Trotz der enormen in das Projekt gesteckten Bemuehungen erfuellen die Resultate des Reengineerings normalerweise nicht die Erwartungen. Es kann passieren, dass sehr bald ein neues, kostspieliges Reengineering erforderlich wird. In dieser Arbeit werden das Problem der Softwareevolution und der Zerfall von Softwarearchitekturen behandelt. Eine Methode wird vorgestellt, welche die Softwareentwicklung in ihrer entscheidenden Phase, dem Architekturrefactoring, unterstuetzt. Die Softwareentwicklung wird sowohl in technischer als auch organisatorischer Hinsicht unterstuetzt. Diese Arbeit hat neue Techniken entwickelt, welche die Reverse-Engineering-, Architecture-Recovery- und Architecture-Redesign-Taetigkeiten unterst uetzen. Sie schlaegt auch Aenderungen des Softwareentwicklungsprozesses vor, die fristgerechte Architekturrefactorings erzwingen koennen und damit die Notwendigkeit der Durchfuehrung eines Architektur- Reengineerings vermeiden. In dieser Arbeit wird die Merkmalmodellierung als Hauptinstrument verwendet. Merkmale werden genutzt, um die Abstraktionsluecke zwischen den Anforderungen der Problemdomaene und der Systemarchitektur zu fuellen. Merkmalmodelle werden auch als erster Grundriss fr die Wiederherstellung der verlorenen Systemarchitektur genutzt. Merkmalbasierte Analysen fuehren zu diversen, nuetzlichen Hinweisen fuer den erneuten Entwurf (das Re-Design) einer Architektur. Schließlich wird die Merkmalmodellierung als Kommunikationsmittel zwischen unterschiedlichen Projektbeteiligten (Stakeholdern) im Verlauf des Softwareengineering-Prozesses verwendet und auf dieser Grundlage wird ein neuer Anforderungsde.nitionsprozess vorgeschlagen, der die erforderlichen Architekturrefactorings erzwingt.The long-life software systems withstand many significant changes throughout their life-cycle in order to follow the evolution of the problem domains. Usually, the software system architecture can not follow the rapid evolution of a problem domain and with time, the diversion of the architecture in respect to the domain features becomes prohibiting for software evolution. For avoiding this problem, periodical refactorings of the system architecture are required. Usually, architecture refactorings are postponed until the very last moment, because of the relatively high risk involved and the lack of short-term profit. As a rule, the management is unwilling to accept architecture refactorings unless they become absolutely necessary. The preferred way of working is to add new system features in an ad-hoc manner and to keep the rule ”Never touch a running system!”. The final result is an architecture decay. The need of performing small refactoring activities turns into need for architecture reengineering. In contrast to refactoring, which is a normal evolutionary activity, reengineering is a kind of software ”revolution”. Reengineering projects are risky and expensive. The effectiveness of reengineering is also usually not as high as expected. When finally after reengineering the required architecture changes take place, it can be too late. Despite the enormous invested efforts, the results of the reengineering usually do not satisfy the expectations. It might happen that very soon a new expensive reengineering is required. This thesis deals with the problem of software evolution and the decay of software architectures. It presents a method, which assists software evolution in its crucial part, the architecture refactoring. The assistance is performed for both technical and organizational aspects of the software evolution. The thesis provides new techniques for supporting reverse engineering, architecture recovery and redesigning activities. It also proposes changes to the software engineering process, which can force timely architecture refactorings and thus avoid the need of performing architecture reengineering. For the work in this thesis feature modeling is utilized as a main asset. Features are used to fill the abstraction gap between domain requirements and system architecture. Feature models are also used as an outline for recovering of lost system architectures. Through feature-based analyses a number of useful hints and clues for architecture redesign are produced. Finally, feature modeling is used as a communication between different stakeholders of the software engineering process and on this basis a new requirements engineering process is proposed, which forces the needed architecture refactorings

Capturing Software Architecture Knowledge for Pattern-Driven Design

Context: Software architecture is a knowledge-intensive field. One mechanism for storing architecture knowledge is the recognition and description of architectural patterns. Selecting architectural patterns is a challenging task for software architects, as knowledge about these patterns is scattered among a wide range of literature. Method: We report on a systematic literature review, with the aim of building a decision model for the architectural pattern selection problem. Moreover, twelve experienced practitioners at software-producing organizations evaluated the usability and usefulness of the extracted knowledge.\newline Results: An overview is provided of 29 patterns and their effects on 40 quality attributes. Furthermore, we report in which systems the 29 patterns are applied and in which combinations. The practitioners confirmed that architectural knowledge supports software architects with their decision-making process to select a set of patterns for a new problem. We investigate the potential trends among architects to select patterns. Conclusion: With the knowledge available, architects can more rapidly select and eliminate combinations of patterns to design solutions. Having this knowledge readily available supports software architects in making more efficient and effective design decisions that meet their quality concerns

A Comparative Study on Model-Driven Requirements Engineering for Software Product Lines

[EN] Model-Driven Engineering (MDE) and Software Product Lines (SPL) are two software development paradigms that emphasize reusing. The former reuse domain knowledge is represented as models and model transformations for product development, and the latter reuse domain knowledge is represented as core assets to produce a family of products in a given domain. The adequate combination of both paradigms can bring together important advantages to the software development community. However, how to manage requirements during a model-driven product line development remains an open challenge. In particular, the Requirements Engineering (RE) activity must deal with specific properties such as variability and commonality for a whole family of products. This paper presents a comparative study of eleven approaches that perform a MDE strategy in the RE activity for SPL, with the aim of identify ing current practices and research gaps. In summary, most of the approaches are focused on the Domain Engineering phase of the SPL development, giving less attention to the Application Engineering phase. Moreover there is a lack of coverage of the Scoping activity, which defines the SPL boundaries. Several approaches apply some model transformations to obtain architectural and application requirements artifacts. Regarding the tool support for requirements specification and management, we found that most of the approaches use only academic prototypes. Regarding the validation of the approaches, the use of Case Studies as a proof of concept was the most commonly used method; however, there is a lack of well-defined case studies and empirical studies to improve the proposals.This research is part of the MULTIPLE project (with ref. TIN2009-13838).Blanes Domínguez, D.; Insfrán Pelozo, CE. (2012). A Comparative Study on Model-Driven Requirements Engineering for Software Product Lines. Revista de Sistemas e Computação. 2(1):3-13. http://hdl.handle.net/10251/43841S3132

Model-Based Systems Engineering Pathfinder: Informing the Next Steps

In 2016, the NASA Engineering and Safety Center established a model-based systems engineering (MBSE) Pathfinder. The primary motivations for establishing the MBSE Pathfinder were to advance the Agency's applications of MBSE and capture lessons-learned to inform the next steps. The MBSE Pathfinder had four teams working in parallel for eight months on different topics of interest to NASA. The teams were encouraged to learn, and use creativity and innovation in their system modeling. The results were captured via reports, webinars, and a knowledge capture meeting. The approach taken for the MBSE Pathfinder was very successful in providing a number of lessons-learned for NASA and for other organizations considering MBSE or pathfinder efforts, and in building a very strong and collaborative user community

Toward a conceptual framework for designing sustainable cyber-physical system architectures: A systematic mapping study

Cyber-physical systems (CPS) represent devices whose components enable interaction between machines and processes. One of the biggest challenges of these systems today is the ability to adjust to changes at the time of execution as they are implemented in environments with a multidimensional complexity, this challenge is currently addressed from the design of the systems themselves by integrating sustainability. With this problem in mind, the present document describes a systematic mapping study of the literature with the goal of demonstrating the current panorama of the frameworks, designs, and/or models used at the time of initiating the development of a cyber-physical system. As a result, it has been concluded that there is a lack of guidelines to construct sustainable, and evolvable cyber-physical systems. To address these issues, a framework for designing sustainable CPS architectures is outlined

A Unified Metamodel for Assessing and Predicting Software Evolvability Quality

Software quality is a key assessment factor for organizations to determine the ability of software ecosystems to meet the constantly changing requirements. Many quality models exist that capture and assess the changing factors affecting the quality of a software product. Common to these models is that they, contrary to the software ecosystems they are assessing, are not evolvable or reusable. The thesis first defines what constitutes a unified, evolvable, and reusable quality metamodel. We then introduce SE-EQUAM, a novel, ontological, quality assessment metamodel that was designed from the ground up to support quality unification, reuse, and evolvability. We then validate the reus-ability of our metamodel through instantiating a domain specific quality assessment model called OntEQAM that assesses evolvability as a non-functional software quality based on product and com-munity dimensions. A fuzzy logic based assessment process that addresses uncertainties around score boundaries supports the evolvability quality assessment. The presented assessment process also uses the unified representation of the input knowledge artifacts, the metamodel, and the model to provide a fuzzy assessment score. Finally, we further interpret and predict the evolvability as-sessment scores using a novel, cross-disciplinary approach that re-applies financial technical analy-sis, which are indicators, and patterns typically used for price analysis and the forecasting of stocks in financial markets. We performed several case studies to illustrate and evaluate the applicability of our proposed evolvability score prediction approach