Model-driven performance analysis of rule-based domain specific visual models

ContextDomain-Specific Visual Languages (DSVLs) play a crucial role in Model-Driven Engineering (MDE). Most DSVLs already allow the specification of the structure and behavior of systems. However, there is also an increasing need to model, simulate and reason about their non-functional properties. In particular, QoS usage and management constraints (performance, reliability, etc.) are essential characteristics of any non-trivial system.ObjectiveVery few DSVLs currently offer support for modeling these kinds of properties. And those which do, tend to require skilled knowledge of specialized notations, which clashes with the intuitive nature of DSVLs. In this paper we present an alternative approach to specify QoS properties in a high-level and platform-independent manner.MethodWe propose the use of special objects (observers) that can be added to the graphical specification of a system for describing and monitoring some of its non-functional properties.ResultsObservers allow extending the global state of the system with the variables that the designer wants to analyze, being able to capture the performance properties of interest. A performance evaluation tool has also been developed as a proof of concept for the proposal.ConclusionThe results show how non-functional properties can be specified in DSVLs using observers, and how the performance of systems specified in this way can be evaluated in a flexible and effective way.     

Model-driven development using UML 2.0: promises and pitfalls

Experience indicates that effective complexity management mechanisms automate mundane development tasks and provide strong support for separation of concerns. For example, current high-level programming languages and integrated development environments provide abstractions that shield developers from intricate lower-level details and offer automated support for transforming abstract representations of source code into faithful machine-executable forms. The Object Management Group initiated the Unified Modeling Language 2.0 effort to address significant problems in earlier versions. While UML 2.0 improves over earlier versions in some aspects, its size and complexity can present a problem to users, tool developers, and OMG working groups charged with evolving the standard.     

模型驱动下的形状分布算法

三维模型的特征提取方法中,形状分布算法简单,具有强的不变性和鲁棒性,但其抽样点不具有代表性,影响了系统的检索精度.为增强抽样点的有效性,我们改进抽样策略,首先引入模型复杂度描述参数,扩大抽样点集;然后利用可分离离散小波变换,逐层分解样点集,增强其有效性,并使最终样点数相同;最后使用形状分布算法进行三维模型的特征提取,并应用在三维模型检索上,对比实验结果表明,改进后的算法提高了系统的检索精度.     

Model-driven reverse engineering

Reverse engineering is the process of comprehending software and producing a model of it at a high abstraction level, suitable for documentation, maintenance, or reengineering. But from a manager's viewpoint, there are two painful problems: 1) It's difficult or impossible to predict how much time reverse engineering will require. 2) There are no standards to evaluate the quality of the reverse engineering that the maintenance staff performs. Model-driven reverse engineering can overcome these difficulties. A model is a high-level representation of some aspect of a software system. MDRE uses the features of modeling technology but applies them differently to address the maintenance manager's problems. Our approach to MDRE uses formal specification and automatic code generation to reverse the reverse-engineering process. Models written in a formal specification language called SLANG describe both the application domain and the program being reverse engineered, and interpretations annotate the connections between the two. The ability to generate a similar version of a program gives managers a fixed target for reverse engineering. This, in turn, enables better effort prediction and quality evaluation, reducing development risk.     

Model-driven disaster management

Disaster management (DM) is a challenging domain to model because of the variety of dynamic characteristics attached to the domain. Metamodeling is a model-driven approach that describes how semantic domain models can be built into an artifact called a Metamodel. By collecting all the domain concepts and partitioning the domain problems into sub-domain-problems, a metamodel can produce a domain-specific language. This paper presents a Disaster Management Metamodel that can serve as a representational layer of DM expertise. This metamodel leads to better knowledge sharing and facilitates combining and matching different DM activities to best manage the disaster on hand.     

Numerical integration in the reconstruction of cardiac action potentials using Hodgkin-Huxley-type models

A comparison between traditional numerical integration methods and a new hybrid integration method for the reconstruction of action potential activity is presented, using a mathematical model of the cardiac Purkinje fiber (MNT model). It is shown that the hybrid integration method reduces importantly the overall computation time required for solving the Hodgkin-Huxley differential equations describing membrane electrical events. To accomplish this, the particular form of the gating variable equations is exploited to reformulate the step-by-step computation. In this way, the time increment can be made much larger compared with traditional methods when the membrane potential changes slowly. A mathematical analysis of the hybrid integration method is presented also, together with a numerical verification of its performance both for the propagated and nonpropagated membrane action potential. It is shown that the local error, that is the error arising at each integration step, and the cumulative integration error are strictly controlled by the membrane potential offset. Using the MNT model, the nonpropagated cardiac Purkinje action potential can be reconstructed in real time with an accuracy of 1% for the potential and 5% for the time of occurrence of its main features. In reconstructing propagated events, the hybrid integration method allows computation time savings by a factor of 10 or more compared to accurate Runge-Kutta schemes.     

Estimating and quantifying the impact of using models for integration and testing

Industrial trends show that the lead time and costs of integrating and testing high-tech multi-disciplinary systems are becoming critical factors for commercial success. In our research, we developed a method for early, model-based integration and testing to reduce this criticality.Although its benefits have been demonstrated in industrial practice, the method requires certain investments to achieve these benefits, e.g. time needed for creating models. Making the necessary trade-off between investments and potential benefits to decide when modeling is profitable is a difficult task that is often based on personal intuition and experience. In this paper, we describe a method based on integration and test sequencing techniques that can be used to make quantitative impact estimations of using models for integration and testing.An industrial case study application of this method shows that it is feasible to quantify the costs and benefits of using models in terms of risk, time, and costs, such that the profitability can be determined.     

Model-driven estimation approach for system reliability using integrated tasks and resources

The increasing complexity of software systems in embedded systems or industrial business domains has led to the importance of reliability analysis for current systems. Reliability analysis has become a crucial part of the system development life cycle, and a new approach is needed to enable an early analysis for reliability estimation, especially for the system under design. However, the existing approach neglects the correlation between system resource and system task for estimating system reliability. This subsequently restricts accuracy of the estimation as well as causing difficulties in identifying critical resources and tasks during the design phase. This paper proposes a model-driven system reliability estimation using a scenario-based approach to estimate system reliability and identify its critical resources and system tasks during the design phase. This model is based on the PerFAM model, which can specifically view timing failures through a system scenario. The proposed approach is validated by the application of a sensitivity analysis into one case study. The case study demonstrates an essential relationship between system reliability, as well as both resources and tasks, which ultimately becomes the integral part for a system reliability estimation assessment.     

Numerical integration in logistic-normal models

Marginal maximum likelihood estimation is commonly used to estimate logistic-normal models. In this approach, the contribution of random effects to the likelihood is represented as an intractable integral over their distribution. Thus, numerical methods such as Gauss-Hermite quadrature (GH) are needed. However, as the dimensionality increases, the number of quadrature points becomes rapidly too high. A possible solution can be found among the Quasi-Monte Carlo (QMC) methods, because these techniques yield quite good approximations for high-dimensional integrals with a much lower number of points, chosen for their optimal location. A comparison between three integration methods for logistic-normal models: GH, QMC, and full Monte Carlo integration (MC) is presented. It turns out that, under certain conditions, the QMC and MC method perform better than the GH in terms of accuracy and computing time.     

信息集成数据模型研究

信息集成是指将多个信息源进行整合,为用户提供一个统一访问这些信息的接口或数据视图。公共数据模型是设计信息集成系统的基本出发点,从分类的角度对信息集成公共数据模型进行研究。对各种数据模型的特点、描述能力、应用领域以及发展现状作了分析和比较。     

Model-driven active visual tracking

We have previously demonstrated that the performance of tracking algorithms can be improved by integrating information from multiple cues in a model-driven Bayesian reasoning framework. Here we extend our work to active vision tracking, with variable camera geometry. Many existent active tracking algorithms avoid the problem of variable camera geometry by tracking view independent features, such as corners and lines. However, the performance of algorithms based on those single features will greatly deteriorate in the presence of specularities and dense clutter. We show, by integrating multiple cues and updating the camera geometry on-line, that it is possible to track a complicated object moving arbitrarily in three-dimensional (3D) space.We use a four degree-of-freedom (4-DoF) binocular camera rig to track three focus features of an industrial object, whose complete model is known. The camera geometry is updated by using the rig control commands and kinematic model of the stereo head. The extrinsic parameters are further refined by interpolation from a previously sampled calibration of the head work space.The 2D target position estimates are obtained by a combination of blob detection, edge searching and gray-level matching, with the aid of model geometrical structure projection using current estimates of camera geometry. The information is represented in the form of a probability density distribution, and propagated in a Bayes Net. The Bayesian reasoning that is performed in the 2D image is coupled by the rigid model geometry constraint in 3D space.An αβ filter is used to smooth the tracking pursuit and to predict the position of the object in the next iteration of data acquisition. The solution of the inverse kinematic problem at the predicted position is used to control the position of the stereo head.Finally, experiments show that the target undertaking arbitrarily 3D motion can be successfully tracked in the presence of specularities and dense clutter.     

模型驱动的Web应用测试

为了保证Web应用软件的质量,需要系统化的方法支持其测试。模型驱动的Web应用测试方法以模型为中心,通过建立Web应用模型描述被测系统,基于该模型产生测试用例,并且使用模型驱动的测试执行工具自动化执行测试,将测试结果返回到各个模型上。该文通过总结比较该领域的研究现状,讨论了实现模型驱动的Web应用测试的关键技术,并提出了目前研究的不足之处及潜在的研究方向和重点。     

模型驱动的Web服务合成

随着已有Web服务数量的不断增加,如何利用现有的Web服务创建新的更复杂的Web服务成为一项新的研究课题。该文提出了MDA模型转换驱动的合成Web服务开发方法,针对Web合成的静态建模部分,提出了建立Web服务静态结构平台无关和平台相关模型的方法,给出了二者之间的转换规则。     

Model-driven vision for in-door navigation

For navigation in a partially known environment it is possible to provide a model that may be used for guidance in the navigation and as a basis for selective sensing. In this paper a navigation system for an autonomous mobile robot is presented. Both navigation and sensing is built around a graphics model, which enables prediction of the expected scene content. The model is used directly for prediction of line segments which, through matching, allow estimation of position and orientation. In addition, the model is used as a basis for a hierarchical stereo matching that enables dynamic updating of the model with unmodelled objects in the environment. For short-term path planning a set of reactive behaviours is used. The reactive behaviours include use of inverse perspective mapping for generation of occupancy grids, a sonar system and simple gaze holding for monitoring of dynamic obstacles. The full system and its component processes are described and initial experiments with the system are briefly outlined.     

一种支持多目标框架的模型驱动开发方法

平台无关模型到平台相关模型的转换是OMG提出的模型驱动架构(MDA)中的关键技术。目前多数开发工具将平台相关模型定义为具体的目标运行框架,这严重降低了软件演化过程中设计模型的可重用性。为此,引入抽象平台相关模型和具体平台相关模型的概念,使基于某种平台的业务逻辑设计与目标运行框架相分离,提出一种支持多目标框架代码生成的扩展MDA开发模型。实验证明,该方法提升了模型描述的灵活性和可重用性,能够对模型驱动的软件开发提供有力的支持。     

The integration of energy policy models

In this paper we present an integrated model for the assessment of alternative U.S. energy policies, based on the Inter-Industry Model constructed by Hudson and Jorgenson and the Natural Gas Model constructed by MacAvoy and Pindyck. We first present the Inter-Industry Model and an outline of the computational techniques employed in implementing the model. We then describe the Natural Gas Model and the details of its implementation.We next present a methodology for integrating energy policy models. The methodology imposes certain consistency requirements on alternative models of the same phenomena. We apply this methodology to the incorporation of exploration and development and wellhead price regulation of natural gas into the integrated energy policy model.Finally, we present four policy simulations with the integrated model. These simulations are the four possible combinations of quotas on oil imports versus no quotas and phased deregulation of the price of natural gas versus no deregulation. Our simulation results support a policy of phased deregulation with no restrictions on oil imports.     

Consistent integration of models based on views of meta models

The complexity of large system models in software engineering nowadays is mastered by using different views. View-based modelling aims at creating small, partial models, each one of them describing some aspect of the system. Existing formal techniques supporting view-based visual modelling are based on typed attributed graphs, where views are related by typed attributed graph morphisms. Such morphisms up to now require a meta model given by a fixed type graph, as well as a fixed data signature and domain. This is in general not adequate for view-oriented modeling where only parts of the complete meta model are known and necessary when modelling a partial view of the system. The aim of this paper is to extend the framework of typed attributed graph morphisms to generalized typed attributed graph morphisms, short GAG-morphisms, which involve changes of the type graph, data signature, and domain. This allows the modeller to formulate type hierarchies and views of visual languages defined by GAG-morphisms between type graphs, short GATG-morphisms. In this paper, we study the interaction and integration of views, and the restriction of views along type hierarchies. In the main result, we present suitable conditions for the integration and decomposition of consistent view models (Theorem 4.1) and extend these conditions to view models defined over meta models with constraints (Theorem 5.1). As a running example, we use a visual domain-specific modelling language to model coarse-grained IT components and their connectors in decentralized IT infrastructures. Using constraints, we formulate connection properties as invariants.     

Model-driven development for early aspects

Currently, non-functional requirements (NFRs) consume a considerable part of the software development effort. The good news is that most of them appear time and again during system development and, luckily, their solutions can be often described as a pattern independently from any specific application or domain. A proof of this are the current application servers and middleware platforms that can provide configurable prebuilt services for managing some of these crosscutting concerns, or aspects. Nevertheless, these reusable pattern solutions presents two shortcomings, among others: (1) they need to be applied manually; and (2) most of these pattern solutions do not use aspect-orientation, and, since NFRs are often crosscutting concerns, this leads to scattered and tangled representations of these concerns. Our approach aims to overcome these limitations by: (1) using model-driven techniques to reduce the development effort associated to systematically apply reusable solutions for satisfying NFRs; and (2) using aspect-orientation to improve the modularization of these crosscutting concerns. Regarding the first contribution, since the portion of a system related to NFRs is usually significant, the reduction on the development effort associated to these NFRs is also significant. Regarding the second contribution, the use aspect-orientation improves maintenance and evolution of the non-functional requirements that are managed as aspects. An additional contribution of our work is to define a mapping and transition from aspectual requirements to aspect-oriented software architectures, which, in turn, contributes to improve the general issue of systematically relating requirements to architecture. Our approach is illustrated by applying it to a Toll Gate case study.     

模型驱动的软件测试研究

MDA(Model-DrivenArchitecture)旨在基于平台无关的模型(PIM)和平台相关的模型(PSM)之间的分离和相互转换来复用平台无关的设计,实现异构中间件平台之间的集成和互操作,从而把软件开发的重点提前到PIM的设计上,也使得在模型级解决测试生成问题成为研究热点。本文从过程、方法与工具三个方面研究了模型驱动的测试,首先提出与软件开发过程集成的模型驱动的软件测试过程;其次讨论了与过程对应的模型驱动的测试方法,基于PIM生成平台无关的测试(PIT),定义并实现了从PIT到平台相关的测试(PST)的映射算法,使得PST能够直接在相应平台上执行以发现软件实现是否与规约一致;最后,对上述过程中的方法提供工具支持。本文过程和方法在一个基于三层Web应用的在线银行系统上得到了实现。