可组合嵌入式软件建模与验证技术研究综述

可组合嵌入式软件以构件开发技术为基础,研究嵌入式构件的建模、组合性质、构件间组合机制以及组合验证等理论、方法和技术.从组合理论、建模与验证技术这3个方面对可组合嵌入式软件的研究现状进行调研分析.组合理论研究给出构件可组合性的乐观定义和悲观定义,从组合操作、组合规则两个方面定义构件间的组合机制.针对嵌入式构件的特点,着重调研了非功能特性和异构构件的建模与组合技术,分析了非功能特性约束、面向多特性的模型等方法.分析了基于契约的验证、基于不变量的验证、基于模型检查的验证等多种嵌入式软件组合验证技术.最后,探讨了需要进一步研究的问题.     

Preserving architectural pattern composition information through explicit merging operators

Composable software systems have been proved to support the adaptation to new requirements thanks to their flexibility. A typical method of composable software development is to select and combine a number of patterns that address the expected quality requirements. Therefore, pattern composition has become a crucial aspect during software design. One of the shortcomings of existing work about pattern composition is the vaporization of composition information which leads to the problem of traceability and reconstructability of patterns. In this paper we propose to give first-class status to pattern merging operators to facilitate the preservation of composition information. The approach is tool-supported and an empirical study has also been conducted to highlight its effectiveness. By applying the approach on the composition of a set of formalized architectural patterns, including their variants, we have shown that composed patterns have become traceable and reconstructable.     

A dynamic constraint satisfaction approach for configuring structural products under mass customization

Configuring structured products poses new challenges to the solving technologies for product configuration. This paper presents a novel and direct approach to encoding configuration models into the Dynamic Constraint Satisfaction Problems (DCSP). In the presented approach, components are encoded as DCSP variables while structural relationships are represented as DCSP activity constraints. Furthermore, the configuration constraints such as the requisition and exclusion constraints are treated as DCSP compatibility constraints, which allow a low-level component to join in the solving process only after its high-level component is selected in the configuration. The presented method allows a more compact encoding representation, compared to CSP and generative CSP. Experimental study shows that the presented DCSP encoding approach makes a significant improvement in the performance of product configuration.     

Systems Development Strategy: A Component Based Approach, The Architecture

An architecture for building laboratory automation systems was developed using the component-based framework. The requirements to build a flexible and adaptable automation system were exemplified through the architectural design process. Existing tools and technologies facilitated the development of this scalable architecture. Several design patterns were used to model this architecture. The influence of these patterns on systems design and the impact of Unified Modeling Language on component and interface design was explored. Integration of the system components with the peripheral components to build an automated system is discussed with emphasis on run-time configuration and component reuse.     

Composing high-performance schedulers: a case study from real-time simulation

Dynamic, high-performance or real-time applications require scheduling latencies and throughput not typically offered by current kernel or user-level threads schedulers. Moreover, it is widely accepted that it is important to be able to specialize scheduling policies for specific target applications and their execution environments. This paper presents one solution to the construction of such high-performance, application-specific thread schedulers. Specifically, scheduler implementations are composed from modular components, where individual scheduler modules may be specialized to underlying hardware characteristics or implement precisely the mechanisms and policies desired by application programs. The resulting user-level schedulers' implementations can provide resource guarantees by interaction with kernel-level facilities which provide means of resource reservation. This paper demonstrates the concept of composable schedulers by construction of several compositions for highly dynamic target applications, where low scheduling latencies are critical to application performance. Claims about the importance and effectiveness of scheduler composition are validated experimentally on a shared-memory multiprocessor. Scheduler compositions are optimized to take advantage of different low-level hardware attributes and of knowledge about application requirements specific to certain applications, including a Time Warp-based real-time discrete event simulator. Experimental evaluations are based on synthetic workloads, on a real-time simulation blending simulated with implemented control system components, and on a dynamic robot control program. Measurements indicate that schedulers can be composed and specialized to offer performance similar to that of dedicated scheduling co-processors. Copyright © 1999 John Wiley & Sons, Ltd.     

Integrated cost/weight optimization of aircraft structures

A methodology for a combined cost/weight optimization of aircraft components is proposed. The objective function is formed by a simplified form of direct operating cost, i.e. by a weighted sum of the manufacturing cost and the component weight. Hence, the structural engineer can perform the evaluation of a design solution based on economical values rather than pure cost or weight targets. The parameter that governs the balance between manufacturing cost and weight is called weight penalty and incorporates the effect of fuel burn, environmental impact or contractual penalties due to overweight. Unlike previous work, the analytical cost model and structural models are replaced by commercially available software packages that allow a more realistic model of the manufacturing costs; further, arbitrary constraints for the structural analysis can be implemented. By means of parametric studies it is shown that the design solution strongly depends on the magnitude of the weight penalty.     

一种CCDL的FPGA设计与实现

多余度技术能够满足飞机管理系统中高安全性、确定性和可靠性的需求,而交叉通道数据链路（ CCDL）是余度计算机之间进行数据和信息交换的重要途径,是保证余度飞机管理计算机正常运转的关键部件。文中基于三余度飞机管理计算机系统需求,给出CCDL硬件逻辑设计的体系架构,对CCDL的关键点进行分析,设计了一种在1394总线上进行点对点可靠传输、防止故障蔓延的交叉通道数据链路,并进行了FPGA实现和验证。实验结果表明,该设计能够高效可靠地满足系统的应用要求。     

A formal model of composing components: the TLA+ approach

In this paper, a method for writing composable TLA⁺ specifications that conform to the formal model called Masaccio is introduced. Specifications are organized in TLA⁺ modules that correspond to Masaccio components by means of a trace-based semantics. Hierarchical TLA⁺ specifications are built from atomic component specifications by parallel and serial composition that can be arbitrary nested. While the rule of parallel composition is a variation of the classical joint-action composition, the authors do not know about a reuse method for the TLA⁺ that systematically employs the presented kind of a serial composition. By combining these two composition rules and assuming only the noninterleaving synchronous mode of an execution, the concurrent, sequential, and timed compositionality is achieved.     

Distributed feature composition: a virtual architecture fortelecommunications services

Distributed Feature Composition (DFC) is a new technology for feature specification and composition, based on a virtual architecture offering benefits analogous to those of a pipe-and-filter architecture. In the DFC architecture, customer calls are processed by dynamically assembled configurations of filter-like components: each component implements an applicable feature, and communicates with its neighbors by featureless internal calls that are connected by the underlying architectural substrate     

动态Web Services的约束满足优化技术研究

Web Services合成是Web Services技术的重要方面,能够按要求提供选择新的服务。本文首先提出了Web Services服务约束的分类描述,进而分析了Web Services服务合成中如何按照服务约束指导服务选择,进而选择合适的服务集来满足客户的要求。该方法把动态Web Services合成转化为约束满足问题。     

A type-centric framework for specifying heterogeneous, large-scale, component-oriented, architectures

Maintaining integrity and consistency, and effecting conformance in architectures of large-scale systems require specification and enforcement of many different forms of structural constraints. While type systems have proved effective for enforcing structural constraints in programs and data structures, most architectural modeling frameworks include only weak notions of typing or rely on first order logic constraint languages that have steep learning curves associated with them and that become unwieldy when scaling to large systems.We present the Cadena Architecture Language with Meta-modeling (CALM) — that uses multi-level type systems to specify and enforce a variety of architectural constraints relevant to the development of large-scale component-based systems. Cadena is a robust and extensible tool that has been used to specify a number of industrial strength component models and applied in multiple industrial research projects on model-driven development and software product lines.     

Energy and spectral dynamics in forced compressible turbulence

Numerical simulations are used to study compressible turbulence with microscale Reynolds numbers up to 40 and rms Mach numbersM up to 0.9. The flows are randomly forced, with energy supplied to either the rotational or compressive components of kinetic energy, which is then transferred to internal energy through the pressure-dilatation interaction and viscous dissipation terms. Coupling between the two components of kinetic energy by the advection term is relatively weak, and most energy introduced to either component by the external force is transferred, without passing through the other component, to internal nergy. A statistically quasiequilibrium of kinetic energy is realized while internal energy increases steadily. The spectral form of the rotational component of velocity, which hardly depends onM, is very close to that for incompressible flow. On the other hand, the compressive component depends strongly onM, especially at large wave numbers.