构件化嵌入式软件的服务质量研究

【作者】 张春梅；

【导师】 李蜀瑜；

【作者基本信息】 陕西师范大学 ， 计算机软件与理论， 2010， 硕士

【摘要】 随着嵌入式技术的飞速发展,嵌入式系统的应用范围变的更加广泛,同时也带动了嵌入式软件需求的日益增加。由于嵌入式系统具有严格的实时性和资源受限等要求,致使传统的以手工编写代码的软件开发技术明显不能满足这种要求。为了提高嵌入式软件的开发效率,降低开发的复杂度、成本和周期,将基于构件的软件开发技术(CBSD)应用于嵌入式系统的开发中是非常合适的。构件技术是当前软件开发的主流形式,具有可复用、可封装和可组装等特点,能显著提高软件质量和开发的专业化程度。具体研究了基于QoS的嵌入式构件的组装和演化两个方面,并且扩展了Lw CCM构件模型和构件容器,提出一个ELw CCM构件模型。结合软构件开发技术的特点,从用户对嵌入式软件的实际需求出发进行研究,研究的主要内容包括以下几个方面：(1)分析了当前Lw CCM构件模型及其应用于嵌入式系统中存在的问题,并对其进行了扩展。首先,根据用户需求,给出一个QoS元模型,并用XML。对部分QoS属性进行描述。其次对Lw CCM构件模型和构件容器进行了扩展,提出一个ELw CCM嵌入式构件模型。增加了QoS反射机制模块,实时QoS策略模块,QoS元模型,QoS评估机制,QoS替换机制,QoS Observer和QoS适应机制模块。最后分析了ELw CCM构件模型的特点。ELw CCM构件模型有效地支持了实时性和资源受限的嵌入式系统,并为基于QoS的构件组装和演化操作奠定了理论基础。(2)对基于QoS嵌入式构件组装进行了研究。分析了目前构件提供者给出的QoS属性值不真实情况,用信任度对QoS值进行修正,并给出用户需求的QoS属性的定义和量化方法。接着分析了蚁群优化算法在组合优化问题中的研究现状和不足,采用多种群并行蚁群优化算法实现构件组装。结合多种群并行搜索的特点,实现种群之间信息的自适应交换,计算出当前搜索到的最短路径的权重,对局部信息素和全局信息素进行更新,同时给出了算法的实现。通过该方法能有效的查找一条组装构件值最优的路径。(3)讨论了QoS驱动的嵌入式构件演化。首先,结合模糊逻辑推理出组装构件的综合服务能力,判断出需要演化的构件。其次,分析了构件演化的原因和运行时构件状态迁移的变化。最后,采用构件替换操作实现了具体的软件演化过程,并给出了一个详细的构件替换策略,分析了替换后状态的一致性保证。(4)以嵌入式音乐点播系统为例,通过通信、编码、分割、合成和解码5类功能不同的构件集验证了基于多种群并行蚁群算法的构件组装,并且对比了单种群算法。以通信功能的新构件选择为例,替换的成功实现,验证了给出的构件替换策略的可行性。更多还原

【Abstract】 As the development of embedded technology, the application of embedded system has become more wider, at the same time which also brings the growth requirement for embedded software increasingly. Embedded system has strict real-time, limited resources, etc., so the traditional software development technology obviously can’t meet these requirements. In order to enhance the development efficiency and reduce the development complexity, cost and time, it is very suitable to employ the component-based software development (CBSD) of embedded technology into embedded system. Now component technology is the fashionable development method, which has the reusable, encapsulation, assemblable, etc., and can significantly improve software quality and development specialization. The paper researches two aspects of component assembly and evolution based QoS for embedded software system, expanses Lw CCM component model and container, and proposed a ELw CCM component modelAccording to the feature for software component development technology, from the user’s actual demands of embedded software, research mainly includes the following aspects:(1) Current light weight CCM(Lw CCM) component model and the problems in embedded system application, as well as expanded Lw CCM. First, a QoS meta-model is given under the user’s requirement and described part of QoS attributes with XML. Then, it expanded Lw CCM component model and container, proposing a ELw CCM embedded component model, including QoS reflective mechanism module, real-time QoS strategies module, QoS mate-model, QoS evaluation mechanism, QoS substitution mechanism, QoS Observer and QoS adaptive mechanism module. Last, it is discussed the ELw CCM component model characteristics, which effectively support the real-time and resource for embedded system, laying a theoretical foundation for component assembly and evolve.(2) The paper has a research on embedded component assembly based QoS. First, we analyze the component provider providing untust QoS value, according to direct and indirect trustiness, compute all the QoS trustiness which are as weights to revise qos value, and give the user requirement definition of QoS attributes and quantitative method. And then the paper analyzed the current research and deficiency of ant colony algorithm in composition optimization problem. We adopt multi parallel ant colony optimization realize component optimization, With multi parallel search feature, use adaptive information exchange between colonies, compute the weight of the current search shortest path, update local and overall pheromone, as well as describe the algorithm implementation. The method can effectively find a value of assembly component route.(3) The paper discuss QoS-driven component evolve in embedded systm. Fist, we evaluate the QoS attributes with fuzzy logic after composited component and find the evolving components. The paper proposes a model of evaluation and evolution. Then, the component state migrations are analyed. Last, component substitution accomplishes evolve process. Paper proposes a detailed component substitution mechanism, which the new component replaces the old one, QoS monitor checks the new composition component and updated embedded software system and guarantee the rationality of the substitution operation.(4) Take embedded audio order system as a example, through communication, coding, segmentation, synthesis and decoding of five different function component sets verify component assembly based multi-ant parallel colony algorithm, compared with the single ant algorithm. It uses the selection of communication functional components, successfully implemented component substitution, which the given replacement policy is feasible更多还原