Reusability of model components for environmental simulation – Case studies for integrated coastal zone management

Model constructs in environmental models are seldom reused beyond the project lifetime or in other modelling studies. A library of reusable model components could facilitate the maintenance of existing models and make the design of new models more efficient. Although component-based design is the common standard in software engineering and manufacturing few examples are yet found in environmental science. The multi-disciplinary project SPICOSA used a common, component-based simulation framework for environmental modelling, based on 18 case studies through Europe. The development of high-quality model components with potential for reuse turned out to be a challenge despite of the guidelines and tutorial examples provided. Well-designed components are of appropriate granularity, encapsulated, with a limited use of connectors and proper data handling. Ultimately, the success of a model library depends on a sufficient set of quality components with complementary functionalities, a framework for quality control, and support of the environmental modelling community.     

Component-based verification using incremental design and invariants

We propose invariant-based techniques for the efficient verification of safety and deadlock-freedom properties of component-based systems. Components and their interactions are described in the BIP language. Global invariants of composite components are obtained by combining local invariants of their constituent components with interaction invariants that take interactions into account. We study new techniques for computing interaction invariants. Some of these techniques are incremental, i.e., interaction invariants of a composite hierarchically structured component are computed by reusing invariants of its constituents. We formalize incremental construction of components in the BIP language as the process of building progressively complex components by adding interactions (synchronization constraints) to atomic components. We provide sufficient conditions ensuring preservation of invariants when new interactions are added. When these conditions are not satisfied, we propose methods for generating new invariants in an incremental manner by reusing existing invariants from the constituents in the incremental construction. The reuse of existing invariants reduces considerably the overall verification effort. The techniques have been implemented in the D-Finder toolset. Among the experiments conducted, we have been capable of verifying safety properties and deadlock-freedom of sub-systems of the functional level of the DALA autonomous robot. This work goes far beyond the capacity of existing monolithic verification tools.     

The Palladio component model for model-driven performance prediction

One aim of component-based software engineering (CBSE) is to enable the prediction of extra-functional properties, such as performance and reliability, utilising a well-defined composition theory. Nowadays, such theories and their accompanying prediction methods are still in a maturation stage. Several factors influencing extra-functional properties need additional research to be understood. A special problem in CBSE stems from its specific development process: Software components should be specified and implemented independently from their later context to enable reuse. Thus, extra-functional properties of components need to be specified in a parametric way to take different influencing factors like the hardware platform or the usage profile into account. Our approach uses the Palladio component model (PCM) to specify component-based software architectures in a parametric way. This model offers direct support of the CBSE development process by dividing the model creation among the developer roles. This paper presents our model and a simulation tool based on it, which is capable of making performance predictions. Within a case study, we show that the resulting prediction accuracy is sufficient to support the evaluation of architectural design decisions.     

VERTAF: an application framework for the design and verification of embedded real-time software

The growing complexity of embedded real-time software requirements calls for the design of reusable software components, the synthesis and generation of software code, and the automatic guarantee of nonfunctional properties such as performance, time constraints, reliability, and security. Available application frameworks targeted at the automatic design of embedded real-time software are poor in integrating functional and nonfunctional requirements. To bridge this gap, we reveal the design flow and the internal architecture of a newly proposed framework called verifiable embedded real-time application framework (VERTAF), which integrates software component-based reuse, formal synthesis, and formal verification. A formal UML-based embedded real-time object model is proposed for component reuse. Formal synthesis employs quasistatic and quasidynamic scheduling with automatic generation of multilayer portable efficient code. Formal verification integrates a model checker kernel from SGM, by adapting it for embedded software. The proposed architecture for VERTAF is component-based and allows plug-and-play for the scheduler and the verifier. Using VERTAF to develop application examples significantly reduced design effort and illustrated how high-level reuse of software components combined with automatic synthesis and verification can increase design productivity.     

Reusing software: issues and research directions

Software productivity has been steadily increasing over the past 30 years, but not enough to close the gap between the demands placed on the software industry and what the state of the practice can deliver; nothing short of an order of magnitude increase in productivity will extricate the software industry from its perennial crisis. Several decades of intensive research in software engineering and artificial intelligence left few alternatives but software reuse as the (only) realistic approach to bring about the gains of productivity and quality that the software industry needs. In this paper, we discuss the implications of reuse on the production, with an emphasis on the technical challenges. Software reuse involves building software that is reusable by design and building with reusable software. Software reuse includes reusing both the products of previous software projects and the processes deployed to produce them, leading to a wide spectrum of reuse approaches, from the building blocks (reusing products) approach, on one hand, to the generative or reusable processor (reusing processes), on the other. We discuss the implication of such approaches on the organization, control, and method of software development and discuss proposed models for their economic analysis. Software reuse benefits from methodologies and tools to: (1) build more readily reusable software and (2) locate, evaluate, and tailor reusable software, the last being critical for the building blocks approach. Both sets of issues are discussed in this paper, with a focus on application generators and OO development for the first and a thorough discussion of retrieval techniques for software components, component composition (or bottom-up design), and transformational systems for the second. We conclude by highlighting areas that, in our opinion, are worthy of further investigation     

基于构件的地理工作流框架:一个方法学的探讨

软件框架为特定领域的软件复用带来了便利.众所周知,软件框架开发的难度要大于开发一个普通可复用构件.采用支持黑盒复用的基于构件的软件框架概念,探讨了地理工作流框架的开发过程.一个地理工作流应用是地理信息领域的工作流管理系统,它可以通过复用地理工作流框架实现.从方法学的角度看,为了开发地理工作流框架,需要进行以下活动:领域分析、领域设计、框架设计和实现.其输出分别是识别了领域变化性的领域模型、领域特定的软件体系结构(DSSA)、软件框架产品.在地理工作流的上下文中,首先对领域变化性进行了识别和分类,包括空间数据类型、空间数据管理、空间操作、过程和空间数据表现5个方面的变化性,它们可以组织成树状视图.然后,为了处理上述变化性,设计了DSSA和框架的软件体系结构,其中前者是后者的模板,而框架体系结构采用HMB风格.最后,对地理工作流框架构件的开发以及框架复用进行了简单描述.与其他地理工作流系统相比,其优势在于由于框架扩展能力带来的灵活性.     

Aligning the economic modeling of software reuse with reuse practices

In contrast to current practices where software reuse is applied recursively and reusable assets are tailored trough parameterization or specialization, existing reuse economic models assume that (i) the cost of reusing a software asset depends on its size and (ii) reusable assets are developed from scratch. The contribution of this paper is that it provides modeling elements and an economic model that is better aligned with current practices. The functioning of the model is illustrated in an example. The example also shows how the model can support practitioners in deciding whether it is economically feasible to apply software reuse recursively.     

Identified adjustability dimensions when generating a product specific requirements specification by requirements reuse

A requirements reuse setups typically includes reusable requirement set(s) containing a collection of reusable requirements and a number of product specific requirements sets which are drawn from the reusable set(s). The ideal scenario when reusing requirements is that all the product requirements can be drawn directly from the reusable set. However, this is rarely the case in product development as new requirements are likely to surface. A critical issue in requirements reuse therefore becomes how to enable products to efficiently reuse requirements as well incorporating changes to the product set. In this paper the objective is not to present a specific method for requirements reuse but to introduce and discuss the possible dimensions of adjustability when generating a product requirement set by reusing requirements from a reusable set. Six adjustability dimensions have been identified. An extensive state of the art is included to introduce the presented methods related to each adjustability dimensions. The options for implementing each adjustability dimensions in a requirement reuse approach are illustrated along with a discussion regarding the benefits and issues resulting from each option. This discussion should help practitioners to better understand the possible methods that can be implemented and to design a user friendly and sustainable approach. A case study, describing how the dimensions are incorporated in two requirements reuse approaches, for Danfoss Solar Inverters (SI) and Danfoss Frequency Drives is provided. As a result an overview of how each adjustability dimensions is implemented in each case is presented. The case study demonstrates that all the identified adjustability dimensions were important elements in requirements reuse implementation. The case study furthermore highlights the need, not only to understand the effects of each adjustability dimension but also of the dependencies to case specific criterions. The classification of adjustability dimensions in requirements reuse and the options for their implementation has not been outlined by previous research and should be a useful contribution both to researchers and practitioners working in the field of requirements reuse.     

A Component Model for Perspective Management of Enterprise Software Reuse

This paper discusses that in order to achieve systematic reuse, the technical and non-technical issues must be considered in parallel, and a set of component models should be built from different perspectives. Each of these models gives a specific view of the components so as to satisfy different needs of different persons involved in the enterprise reuse program. Especially, we present a reusable component model – FLP model for reusable component, which describes components from three dimensions (form, level, and presentation) and views components and their relationships from the perspective of process and management. This model determines the sphere of reusable components, the time points of reusing components in the development process, and the needed means to present components in terms of the abstraction level, logic granularity and presentation media. It is the basis on which the management and technical decisions are made. It will be used as the kernel model to initialize and normalize a systematic enterprise reuse program. After the FLP model, the relationships among these different models are discussed. Furthermore, the usage of these models to facilitate the perspective management of enterprise software reuse is discussed.     

Automatic synthesis and verification of real-time embedded software for mobile and ubiquitous systems

Currently available application frameworks that target the automatic design of real-time embedded software are poor in integrating functional and non-functional requirements for mobile and ubiquitous systems. In this work, we present the internal architecture and design flow of a newly proposed framework called Verifiable Embedded Real-Time Application Framework (VERTAF), which integrates three techniques namely software component-based reuse, formal synthesis, and formal verification. Component reuse is based on a formal unified modeling language (UML) real-time embedded object model. Formal synthesis employs quasi-static and quasi-dynamic scheduling with multi-layer portable efficient code generation, which can output either real-time operating systems (RTOS)-specific application code or automatically generated real-time executive with application code. Formal verification integrates a model checker kernel from state graph manipulators (SGM), by adapting it for embedded software. The proposed architecture for VERTAF is component-based which allows plug-and-play for the scheduler and the verifier. The architecture is also easily extensible because reusable hardware and software design components can be added. Application examples developed using VERTAF demonstrate significantly reduced relative design effort as compared to design without VERTAF, which also shows how high-level reuse of software components combined with automatic synthesis and verification increases design productivity.     

Building enterprise reuse program——A model-based approach

Reuse is viewed as a realistically effective approach to solving software crisis. For an organization that wants to build a reuse program, technical and non-technical issues must be considered in parallel. In this paper, a model-based approach to building systematic reuse program is presented. Component-based reuse is currently a dominant approach to software reuse. In this approach, building the right reusable component model is the first important step. In order to achieve systematic reuse, a set of component models should be built from different perspectives. Each of these models will give a specific view of the components so as to satisfy different needs of different persons involved in the enterprise reuse program. There already exist some component models for reuse from technical perspectives. But less attention is paid to the reusable components from a non-technical view, especially fromthe view of process and management. In our approach, a reusable component model--FLP modelfor reusable component     

Stateful component-based performance models

The accuracy of performance-prediction models is crucial for widespread adoption of performance prediction in industry. One of the essential accuracy-influencing aspects of software systems is the dependence of system behaviour on a configuration, context or history related state of the system, typically reflected with a (persistent) system attribute. Even in the domain of component-based software engineering, the presence of state-reflecting attributes (the so-called internal states) is a natural ingredient of the systems, implying the existence of stateful services, stateful components and stateful systems as such. Currently, there is no consensus on the definition or method to include state-related information in component-based prediction models. Besides the task to identify and localise different types of stateful information across component-based software architecture, the issue is to balance the expressiveness and complexity of prediction models via an effective abstraction of state modelling. In this paper, we identify and classify stateful information in component-based software systems, study the performance impact of the individual state categories, and discuss the costs of their modelling in terms of the increased model size. The observations are formulated into a set of heuristics-guiding software engineers in state modelling. Finally, practical effect of state modelling on software performance is evaluated on a real-world case study, the SPECjms2007 Benchmark. The observed deviation of measurements and predictions was significantly decreased by more precise models of stateful dependencies.     

Simulation model reuse: definitions, benefits and obstacles

The term ‘simulation model reuse’ can be taken to mean various things from the reuse of small portions of code, through component reuse, to the reuse of complete models. On a more abstract level, component design, model design and modelling knowledge are prime candidates for reuse. The reuse of simulation models is especially appealing, based on the intuitive argument that it should reduce the time and cost for model development. In a discussion with four simulation modelling experts, however, a number of issues were raised that mean these benefits may not be obtainable. These issues include the motivation to develop reusable models, the validity and credibility of models to be reused, and the cost and time for familiarisation. An alternative simulation methodology was proposed, that may lend itself better to model reuse.     

Building enterprise reuse program

Reuse is viewed as a realistically effective approach to solving software crisis. For an organization that wants to build a reuse program, technical and non-technical issues must be considered in parallel. In this paper, a model-based approach to building systematic reuse program is presented. Component-based reuse is currently a dominant approach to software reuse. In this approach, building the right reusable component model is the first important step. In order to achieve systematic reuse, a set of component models should be built from different perspectives. Each of these models will give a specific view of the components so as to satisfy different needs of different persons involved in the enterprise reuse program. There already exist some component models for reuse from technical perspectives. But less attention is paid to the reusable components from a non-technical view, especially from the view of process and management. In our approach, a reusable component model—FLP model for reusable component—is introduced. This model describes components from three dimensions (Form, Level, and Presentation) and views components and their relationships from the perspective of process and management. It determines the sphere of reusable components, the time points of reusing components in the development process, and the needed means to present components in terms of the abstraction level, logic granularity and presentation media. Being the basis on which the management and technical decisions are made, our model will be used as the kernel model to initialize and normalize a systematic enterprise reuse program.     

A case study of environmental modelling and simulation using transplantable components

Recent changes in environmental modelling practice have included adoption of modern software engineering concepts of model reuse, extensibility and flexibility, and development of better visual user interfaces. Additionally, the concepts of component-based software development and use of object-oriented programming have produced new environmental modelling methods. These changes have been supported by development of a range of modelling environments that allow rapid creation of environmental models from components. To date there has been little exploration of the opportunities that modelling environments offer in terms of flexible model construction by transplanting components. In the work reported here, simple catchment-based nonpoint source pollution models are constructed using the ICMS modelling environment, and a number of different data types and components are used within a single model structure to estimate pollution loads. Models include a bulk runoff-concentration load calculation, an export coefficient model, and land-use specific runoff and loads. It was found that, when applied using a powerful and flexible modelling environment, the component-based modelling concept provides not only an elegant method for model development, but also the opportunity to explore model expansion and refinement through use of transplantable components.     

设计重用技术理论体系研究

围绕设计重用这一思想,首次提出设计重用技术,将重用的范围扩展到产品的广义设计领域。用系统和集成的观点对设计重用技术的理论体系及其系统的组成进行了研究。粗略地将设计重用技术的研究内容划分为3个方面:可重用集成设计单元建模技术;可重用集成设计单元的重用技术;设计重用技术实施策略和方法。介绍了设计重用涉及的技术领域及关键因素,提出了新的适应设计重用的产品设计信息流程。最后,从FTQCSE6个企业竞争力要素方面分析了设计重用技术对企业市场竞争力的影响。     

构件化动态政府门户通用平台的研究与应用

基于构件的软件开发可以复用已有的应用系统、应用框架,开发出具有良好的可维护性和软件资源的可复用性,并有较强的用户需求变化适应能力的软件。构件的可复用性越高、复用越广泛,其复用次数就会越多,价值也越大。该文研究了基于构件的通用政府门户平台,提出了基于构件的政务通门户系统开发框架,可重用构件是其重要的一部分。该门户平台类似于一个网站生成器,通过简单的拖拉拽等操作就可以完成不同政府的门户平台系统的生成工作。     

基于分布构件的软件性能工程

软件性能工程将软件的性能属性与软件工程技术结合起来,使得软件在早期设计时就能对其性能进行评估。随着分布构件技术的普及,部署过程与动态重构成为软件生命周期的重要组成部分,对软件性能有重大的影响。传统的SPE技术对软件性能的跟踪和追溯在部署和动态重构阶段会被中断,因此不适用于分布构件技术。本文针对基于分布构件技术软件的性能问题,提出了分布构件化软件性能工程技术,使得SPE能够被应用到构件的组装、部署和动态重构阶段。     

一种支持设计时软件重用的方法ArchBean

目前,在设计阶段重用软件体系结构所面临的主要问题是:虽然存在大量的具有重用价值的体系结构制品,但是这些制品却难以得到成功的重用.提出了一种支持软件体系结构设计时重用的ArchBean方法.该方法基于反射机制将支持重用的元信息和体系结构制品本身封装成自包含、自描述的大粒度可重用资.源.给出了支持这种方法的反射机制RMRSA和反射式软件体系结构.基于Object-Z形式化描述了PMB协议.详细给出了基于ArchBean方法的支撑工具ArchBean Studio的设计和实施过程.