Modal logics for reasoning about object-based component composition

Component-oriented development of software supports the adaptability and maintainability of large systems, in particular if requirements change over time and parts of a system have to be modified or replaced. The software architecture in such systems can be described by components and their composition. In order to describe larger architectures, the composition concept becomes crucial. We will present a formal framework for component composition for object-based software development. The deployment of modal logics for defining components and component composition will allow us to reason about and prove properties of components and compositions

On Composing Separated Concerns, Composability and Composition Anomalies

It is generally acknowledged that separation of concerns is a key requirement for effective software engineering: it helps in managing the complexity of software and supports the maintainability of a software system. Separation of concerns makes only sense if the realizations in software of these concerns can be composed together effectively into a working program. The ability to compose systems from independently developed components that can be adapted and extended easily is a long-standing goal in the software engineering discipline. However, both research and practice have shown that composability of software is far from trivial and fails repeatedly. Typically this occurs when components exhibit complex behavior, in particular when multiple concerns are involved in a single component. We believe that, to address the composability problems, we need a better understanding of the requirements involved in successful composition, and in addition define the situations where composition fails. To this aim, in this paper we introduce a number of requirements for designlevel composability and define a category of composition problems that are inherent for given composition models, which we term as composition anomalies

Composing Software from Multiple Concerns: A Model and Composition Anomalies

Constructing software from components is considered to be a key requirement for managing the complexity of software. Separation of concerns makes only sense if the realizations of these concerns can be composed together effectively into a working program. Various publications have shown that composability of software is far from trivial and fails when components express complex behavior such as constraints, synchronization and history-sensitiveness. We believe that to address the composability problems, we need to understand and define the situations where composition fails. To this aim, in this paper we (a) introduce a general model of multi-dimensional concern composition, and (b) define so-called composition anomalies

A learning apprentice for software parts composition

An overview of the knowledge acquisition component of the Bauhaus, a prototype computer aided software engineering (CASE) workstation for the development of domain-specific automatic programming systems (D-SAPS) is given. D-SAPS use domain knowledge in the refinement of a description of an application program into a compilable implementation. The approach to the construction of D-SAPS was to automate the process of refining a description of a program, expressed in an object-oriented domain language, into a configuration of software parts that implement the behavior of the domain objects

Software Reliability in Semantic Web Service Composition Applications

Web Service Composition allows the development of easily reconfigurable applications that can be quickly adapted to business changes. Due to the shift in paradigm from traditional systems, new approaches are needed in order to evaluate the reliability of web service composition applications. In this paper we present an approach based on intelligent agents for semiautomatic composition as well as methods for assessing reliability. Abstract web services, corresponding to a group of services that accomplishes a specific functionality are used as a mean of assuring better system reliability. The model can be extended with other Quality of Services – QoS attributes.Software Reliability, Web Service Composition, Intelligent Agents

Composition and Self-Adaptation of Service-Based Systems with Feature Models

The adoption of mechanisms for reusing software in pervasive systems has not yet become standard practice. This is because the use of pre-existing software requires the selection, composition and adaptation of prefabricated software parts, as well as the management of some complex problems such as guaranteeing high levels of efficiency and safety in critical domains. In addition to the wide variety of services, pervasive systems are composed of many networked heterogeneous devices with embedded software. In this work, we promote the safe reuse of services in service-based systems using two complementary technologies, Service-Oriented Architecture and Software Product Lines. In order to do this, we extend both the service discovery and composition processes defined in the DAMASCo framework, which currently does not deal with the service variability that constitutes pervasive systems. We use feature models to represent the variability and to self-adapt the services during the composition in a safe way taking context changes into consideration. We illustrate our proposal with a case study related to the driving domain of an Intelligent Transportation System, handling the context information of the environment.Work partially supported by the projects TIN2008-05932, TIN2008-01942, TIN2012-35669, TIN2012-34840 and CSD2007-0004 funded by Spanish Ministry of Economy and Competitiveness and FEDER; P09-TIC-05231 and P11-TIC-7659 funded by Andalusian Government; and FP7-317731 funded by EU. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

In vitro analysis of urinary stone composition in dual-energy computed tomography

Purpose: Dual energy computed tomography (DECT) is a new method of computed tomography (CT) imaging, allowing the assessment of not only the object's morphology, but also its composition. The aim of the study was to evaluate the potential of in vitro DECT evaluation of urinary stones' chemical composition. Material and methods: Six samples of surgically removed renal stones were scanned using DECT and analyzed by scanner vendor software. Uric acid stones were marked red and calcium stones white by the software. The real composition of the stones was finally verified using physicochemical laboratory analysis. Results: In 5 out of 6 samples, the composition of stones in DECT (3 samples identified as uric acid and 2 samples as calcium) was consistent with the physicochemical analysis (3 samples identified as uric acid, 1 as calcium phosphate, 1 as calcium oxalate). In DECT it was not possible to determine more precisely the type of calcium compounds (calcium phosphate vs. calcium oxalate) as established in the physicochemical analysis. In one stone identified in physicochemical analysis as uric acid, DECT detected a composite layered structure containing both uric acid and calcium compounds. Conclusions: DECT allows uric acid to be distinguished from calcium urinary tract stones, which is crucial in the choice of appropriate therapy. Using the available hardware and software, it was not possible to more accurately distinguish types of calcified stones. Evaluation of the stone type in DECT may be limited in the case of mixed chemical composition

Cyclical Flow: Spatial Synthesis Sound Toy as Multichannel Composition Tool

This paper outlines and discusses an interactive system designed as a playful ‘sound toy’ for spatial composition. Proposed models of composition and design in this context are discussed. The design, functionality and application of the software system is then outlined and summarised. The paper concludes with observations from use, and discussion of future developments

On the design of aspect-oriented composition models for software evolution

Aspect-oriented programming is an emerging approach in software development,\ud which provides new possibilities for separation of concerns. Aspectoriented\ud languages offer abstractions for the implementation of concerns\ud whose modularization cannot be achieved by using traditional programming\ud languages. Such concerns are generally termed as crosscutting concerns. It is\ud generally agreed that separating the right concerns from each other enhances\ud software quality factors such as reusability and adaptability. The separated\ud concerns in software must be composed together so that software behaves\ud according to its requirements in a coherent way. We refer to language mechanisms\ud that separate and compose concerns as 'composition mechanisms'. This\ud thesis evaluates the software composition mechanisms of current aspectoriented\ud languages from the perspective of software quality factors such as\ud evolvability, comprehensibility, predictability and adaptability. Based on this\ud study, the thesis proposes novel extensions to current aspect-oriented\ud languages so that programs written in these languages exhibit better quality.\ud A considerable number of aspect-oriented languages has been introduced for\ud modularizing crosscutting concerns. Naturally, these languages share a number\ud of common concepts and have distinctive features as well. For this reason, we\ud propose a reference model that aims to capture the common and distinctive\ud concepts of aspect-oriented languages. This reference model provides a basis\ud to understand the important characteristics of the state-of-the-art AOP\ud languages and helps us to compare the AOP languages with each other.\ud Furthermore, it exposes the issues that have to be considered when a new\ud aspect-oriented language needs to be developed.\ud In this thesis, we analyse the four main aspect-oriented concepts of the reference\ud model, namely join point, pointcut, advice and aspect, and identify problems\ud related to their use in various AOP languages. Based on this analysis, we\ud propose extensions of the existing concepts and/or design new ones to address\ud the identified problems.\ud In current aspect-oriented languages, pointcuts select join points of a program\ud based on lexical information such as explicit names of program elements.\ud However, this reduces the adaptability of software, since it involves too much\ud information that is hard-coded, and often implementation-specific. We claim\ud that this problem can be reduced by referring to program elements through their\ud semantic properties. A semantic property describes for example the behavior\ud of a program element or its intended meaning. We formulate requirements for\ud the proper application of semantic properties in aspect-oriented programming.\ud We discuss how to use semantic properties for the superimposition of aspects,\ud and how to apply superimposition to bind semantic properties to program\ud elements. To achieve this, we propose language constructs that support semantic\ud composition: the ability to compose aspects with the elements of the base\ud program that satisfy certain semantic properties.\ud The current advice-pointcut binding constructs of AOP languages maintain\ud explicit dependencies to advices and aspects. This results in weaving specifications\ud that are less evolvable and need more maintenance during the development\ud of a system. We show that this issue can be addressed by providing associative\ud access to advices and aspects instead of using explicit dependencies in\ud the weaving specification. To this aim, we propose to use a designating (query)\ud language in advice-pointcut bindings that allows for referring aspect/advices\ud through their (syntactic and semantic) properties. We also present how semantic\ud properties can be applied to provide reusable (adaptable) aspect abstractions.\ud Aspect-oriented languages provide means to superimpose aspectual behavior –\ud in terms of advices - on a given set of join points. It is possible that not just a\ud single, but several advices need to execute at the same join point. Such "shared"\ud join points may give rise to issues such as determining the exact execution\ud order and the other possible dependencies among the aspects. We present a\ud detailed analysis of the problem, and identify a set of requirements upon mechanisms\ud for composing aspects at shared join points. To address the identified\ud issues, we propose a general and declarative model for defining constraints\ud upon the possible compositions of aspects at a shared join point. By using an\ud extended notion of join points, we show how concrete aspect-oriented\ud programming languages can adopt the proposed model.\ud The thesis also presents how the proposed extensions and new constructs are\ud adopted by the aspect-oriented language Compose*. To evaluate the proposed\ud constructs, we provide qualitative analyses with respect to various software\ud engineering properties, such as evolvability, modularity, predictability and\ud adaptability