Design and evaluation of a generic software architecture foron-demand video servers

Introduces the design, implementation and evaluation of a generic software architecture for on-demand video servers. We describe different key components for controlling the storage and network devices within the server. The interactive collaborations between these software components are also illustrated. The experimental results indicate a very promising direction in exploring the right combinations of these software components. The server is thus able to increase the number of concurrent video accesses with the same hardware configuration. For instance, with the right combinations, the system achieved about 80% of the storage system bandwidth of four disks, about 70% of the storage system bandwidth of six disks, and generally reached the maximal achieved SCSI bandwidth when eight disks are used over two SCSI buses. Our research and experimental results are based on video servers currently under construction across a variety of hardware platforms, including SMP, DMP and clusters of PCs or workstations. The most advanced prototype server is based on an SGI shared-memory multiprocessor with a mass storage system consisting of RAID-3 disk arrays. With all the enabling/management schemes, we were able to further investigate interesting research issues by considering the user's access profiles for taking advantage of popular video titles. The results were significant, with a range of 60% improvement given a 512 kByte block size. In addition to the experimental results, theoretical performance models were also developed that closely match to our collected experimental results     

Applying empirical software engineering to software architecture: challenges and lessons learned

In the last 15 years, software architecture has emerged as an important software engineering field for managing the development and maintenance of large, software-intensive systems. Software architecture community has developed numerous methods, techniques, and tools to support the architecture process (analysis, design, and review). Historically, most advances in software architecture have been driven by talented people and industrial experience, but there is now a growing need to systematically gather empirical evidence about the advantages or otherwise of tools and methods rather than just rely on promotional anecdotes or rhetoric. The aim of this paper is to promote and facilitate the application of the empirical paradigm to software architecture. To this end, we describe the challenges and lessons learned when assessing software architecture research that used controlled experiments, replications, expert opinion, systematic literature reviews, observational studies, and surveys. Our research will support the emergence of a body of knowledge consisting of the more widely-accepted and well-formed software architecture theories.     

安全数据采集系统层次化通用软件体系结构研究

根据模型驱动体系结构方法学的思想,提出了一种安全数据采集系统(SC-DAS)的层次化通用软件体系结构.该体系结构分为数据采集通讯层、可信网络接入层以及安全网络传输层等三层,以及客户端、客户端可信代理、信息流策略执行点,策略决策点以及数据服务器5个子系统.详细的介绍了各层包含的主要协议、相关交互模型以及各个子系统的功能.该体系结构可以有效地确保安全数据采集系统的安全性,并为系统的软件复用和快速开发提供了体系层面上的支持.     

A software architecture centric engineering approach for Internetware

As a new software paradigm evolved by the Internet, Internetware brings many challenges for the traditional software development methods and techniques. Though architecture-based component composition (ABC) approach is originated in the traditional software paradigm, it supports the engineering of Internetware effectively due to its philosophy, rationales and mechanisms. ABC has three major contributions to the en- gineering of Internetware in detail. First, the feature oriented domain modeling method can structure the “disordered”“software entities” to “ordered Internetware” bottom-up in the problem space. Second, the architecture centric design and analysis method can support the development of self-adaptive Internetware. Third, the component operating platform is a reflective and self-adaptive middleware that not only provides Internetware with a pow- erful and flexible runtime infrastructure but also enables the self-adaptation of the structure and individual entities of Internetware.     

基于产品线体系结构的软件工程过程模型研究

在借鉴现代工业的组织体系、管理规范、生产流程的基础上,针对基于软件产品线体系结构的软件工程方法和开发过程进行了系统研究,提出了基于产品线体系结构而实现软件工程化生产的N-生命周期模型.该模型的建立,对研究基于软件产品线体系结构的集成化软件工程环境,进而实现软件产品的工业化生产是非常有益且重要的.     

MASSC: a generic architecture for multiapplication smart cards

Optimized smart cards must be derived from a generic platform and come with tools to help design and manage services. Also of paramount importance is payback and cost- and performance-optimized solutions to manage end-to-end security     

GUARDS: a generic upgradable architecture for real-time dependablesystems

The development and validation of fault-tolerant computers for critical real-time applications are currently both costly and time consuming. Often, the underlying technology is out-of-date by the time the computers are ready for deployment. Obsolescence can become a chronic problem when the systems in which they are embedded have lifetimes of several decades. This paper gives an overview of the work carried out in a project that is tackling the issues of cost and rapid obsolescence by defining a generic fault-tolerant computer architecture based essentially on commercial off-the-shelf (COTS) components (both processor hardware boards and real-time operating systems). The architecture uses a limited number of specific, but generic, hardware and software components to implement an architecture that can be configured along three dimensions: redundant channels, redundant lanes, and integrity levels. The two dimensions of physical redundancy allow the definition of a wide variety of instances with different fault tolerance strategies. The integrity level dimension allows application components of different levels of criticality to coexist in the same instance. The paper describes the main concepts of the architecture, the supporting environments for development and validation, and the prototypes currently being implemented     

An exploratory study on ontology engineering for software architecture documentation

The usefulness of Software Architecture (SA) documentation depends on how well its Architectural Knowledge (AK) can be retrieved by the stakeholders in a software project. Recent findings show that the use of ontology-based SA documentation is promising. However, different roles in software development have different needs for AK, and building an ontology to suit these needs is challenging. In this paper we describe an approach to build an ontology for SA documentation. This approach involves the use of typical questions for eliciting and constructing an ontology. We outline eight contextual factors, which influence the successful construction of an ontology, especially in complex software projects with diverse AK users. We tested our ‘typical question’ approach in a case study and report how it can be used for acquiring and modeling AK needs.     

An architecture process maturity model of software product line engineering

Software architecture has been a key research area in the software engineering community due to its significant role in creating high-quality software. The trend of developing product lines rather than single products has made the software product line a viable option in the industry. Software product line architecture (SPLA) is regarded as one of the crucial components in the product lines, since all of the resulting products share this common architecture. The increased popularity of software product lines demands a process maturity evaluation methodology. Consequently, this paper presents an architecture process maturity model for software product line engineering to evaluate the current maturity of the product line architecture development process in an organization. Assessment questionnaires and a rating methodology comprise the framework of this model. The objective of the questionnaires is to collect information about the SPLA development process. Thus, in general this work contributes towards the establishment of a comprehensive and unified strategy for the process maturity evaluation of software product line engineering. Furthermore, we conducted two case studies and reported the assessment results, which show the maturity of the architecture development process in two organizations.     

Pipelines: Modelling a software architecture through relations

A pipeline is a popular architecture which connects computational components (filters) through connectors (pipes) so that computations are performed in a stream like fashion. The data are transported through the pipes between filters, gradually transforming inputs to outputs. This kind of stream processing has been made popular through UNIX pipes that serially connect independent components for performing a sequence of tasks. We show in this paper how to formalize this architecture in terms of monads, hereby including relational specifications as special cases. The system is given through a directed acyclic graph the nodes of which carry the computational structure by being labelled with morphisms from the monad, and the edges provide the data for these operations. It is shown how fundamental compositional operations like combining pipes and filters, and refining a system by replacing simple parts through more elaborate ones, are supported through this construction.Received: 23 September 2002 / 4 May 2003     

A model-driven software engineering workflow and tool architecture for servitised manufacturing

Modern manufacturing businesses increasingly engage in servitisation, by offering advanced services along with physical products, and creating “product–service systems”. Information Technology infrastructures, and especially software, are a critical part of modern service provision. However, software development in this context has not been investigated and there are no development methods or tools specifically adapted to the task of creating software for servitised businesses in general, or manufacturing in particular. In this paper, we define the requirements for software engineering in servitised manufacturing. Based on these, we describe a model-driven software engineering workflow for servitised manufacturing, supporting both structural and behavioural modelling of the service system. Furthermore, we elaborate on the architecture of an appropriate model-driven Integrated Development Environment (IDE). The proposed workflow and a prototype implementation of the IDE were evaluated in a set of industrial pilots, demonstrating improved communication and collaboration between participants in the software engineering process.     

Value-based software engineering: a case study

The information technology field's accelerating rate of change makes feedback control essential for organizations to sense, evaluate, and adapt to changing value propositions in their competitive marketplace. Although traditional project feedback control mechanisms can manage the development efficiency of stable projects in well-established value situations, they do little to address the project's actual value, and can lead to wasteful misuse of an organization's scarce resources. The value-based approach to software development integrates value considerations into current and emerging software engineering principles and practices, while developing an overall framework in which these techniques compatibly reinforce each other.     

An architecture for generic extensions

We examine what is necessary to allow generic libraries to be used naturally in a multi-language, potentially distributed environment. Language-neutral library interfaces usually do not support the full range of programming idioms that are available when a library is used natively. We investigate how to structure the language bindings of the neutral interface to achieve a better expressibility and code re-use. We furthermore address how language-neutral interfaces can be extended with import bindings to recover the desired programming idioms. We also address the question of how these extensions can be organized to minimize the performance overhead that arises from using objects in manners not anticipated by the original library designers. Our approach is to treat a library as a software component and to view the problem as one of component extension. We use C++ as an example of a mature language, with libraries using a variety of patterns, and use the Standard Template Library as an example of a complex library for which efficiency is important. By viewing the library extension problem as one of component organization, we enhance software composibility, hierarchy maintenance and architecture independence.     

Simulating a software engineering apprenticeship

We examine the prevailing software engineering (SE) body of knowledge and perspectives on SE education to construct a model comprising knowledge areas for SE professional development. We use this model and Benjamin Bloom's taxonomy to delineate knowledge areas that an apprenticeship could best handle. We then establish a framework for SE apprenticeship, which we use to examine practices for apprenticeship simulations in three academic institutions that offer computer science (CS), applied CS, or computing systems curricula.     

Standards: defining software engineering as a profession

The need for standards of personal accountability for professionals working in the field of software engineering is examined. The field is defined, and the technical expertise and entry-level requirements that it requires are identified. Ways to initiate the process of obtaining a broad professional consensus on the norms of the software engineering field are proposed     

Function-class decomposition: a hybrid software engineering method

In addition to offering a simple yet powerful method for decomposing a system, function-class decomposition (FCD) produces an architecture that is more supportive than traditional object-oriented decomposition for several software engineering tasks. A hybrid method that integrates structured analysis with an OO approach, FCD identifies classes in parallel with decomposing the system into a hierarchy of functional modules. Recently, developers extended FCD to integrate UML concepts. Useful for partitioning a system for distribution, the FCD hierarchy provides a framework for controlling development in a distributed software engineering environment. It also helps identify and integrate components in component-based development and supports the system life-cycle maintenance phase. Further, FCD addresses many of the initial analysis and design problems inherent in large and complex OO systems. The authors' experience with testing FCD on several applications validates its compatibility with OO methodologies and modeling techniques     

TAP: a software architecture for an inquiry dialogue-based tutoringsystem

In the tutoring agenda planner (TAP) project, we study the feasibility of implementing the inquiry teaching method of Collins and Stevens (1991) as tutoring software. This paper describes the software architecture for TAP-1-a simple inquiry tutoring shell based on the theory of inquiry teaching. The inquiry teaching style has the objective of teaching scientific reasoning skills through a “localized” sequence of well-planned inquiry dialogue. To complement the “localized” dialogue planning framework inherent in the theory of inquiry teaching, the TAP-1 architecture has adopted the “global” curriculum planning technique. TAP-1 has successfully demonstrated the inquiry teaching style through an inquiry planner within an intelligent tutoring system shell. In addition, PADI-a geography tutor that delivers inquiry teaching style-has been implemented using TAP-1. A group of students performed well in an evaluation activity of the tutor. They also foresaw the potential of TAP for achieving the aim of cultivating scientific thoughts     

Traditional Japanese architecture blends beauty and rationale[lessons for software engineering]

It's hard to find a good instance of harmonization of beauty and rationale in the field of software engineering. We can, however, find it in ancient Japanese architecture which is where we might find the clues we need to achieve our goal. Unfortunately, the software community is relatively young, so there are few such secrets or literatures to use as a basis for our communications. Moreover, because the structure of software is not obvious yet architectural structures are clearly visible-the difficulty we face might be larger and deeper than that of other disciplinary fields. However, by carefully examining ancient architectural methods, we believe that we are stepping in the right direction in our pursuit of the patterns that will realize the harmony of beauty and rationale     

Coordination implications of software architecture in a global software development project

In this paper, we report on our experience of using design structure matrices (DSMs), derived from architecture models developed at early stages of the project, to reveal the coordination needs among globally distributed development teams. Our approach is to automatically transform the box-and-line style software architecture model into an augmented constraint network (ACN), from which a DSM can be automatically generated. After that, we represent the coordination structure among the team members as communication matrices (COMs). We then assess the consistency between the DSM and COMs. Analysis of data gathered during the Global Studio Project Version 3.0 revealed that the architectural DSM model, representing the software modular structure, is highly consistent with the COMs that represent the actual coordination structure, showing that an architectural DSM has the potential to help guide the task assignments in global software development projects.     

A generic model for software architectures

In other industries, the idea of build corporate culture by establishing a common level of “best practice” is widely known and used. The architecture concept directly supports this goal for our industry and can help us improve problem areas dominated by organizational and social issues, such as health care organizations, educational systems, and so on. Our proposed reference model for architecture specification and development is organized around a set of aspects that structure concepts and rules; these, in turn, specify a conceptual architecture. We have added principles and guidelines to the concepts and rules to give a more complete picture of the architecture and to provide a place to store and communicate successfully applied design patterns and other knowledge related to the architecture. Adding architectural elements is a step toward a more constructive type of architecture representation. Our current research is focused on further refining these concepts and developing a formal specification of the architecture reference model. We are continuing to test our ideas in case studies, such as applying our model to the OSCA architecture and the application machine concept. We are also developing a prototype architecture editor, and we are testing different tools to learn more about integrating them into a real infrastructure and to learn what typical services an infrastructure must provide