局域网流媒体Caching代理服务器的实现

With the widespread use of streaming media application on the Internet, a significant change in Internet workload will be provoked.Caching is one kind of applied technique relatively for enhancing the scalability of streaming system and reducing the workload of server/network. We have utilized RTP/RTSP protocol, and implemented the prototype of streaming proxy caching based on LAN in visual C-t-t-environment with WINSOCK network interface. This system can play a role in decreasing server load, reducing the traffic from streaming server to proxy, and improving the Start-up latency of the client.     

分布式协作模型及应用研究

With the development of the Web technology,the application environment has acquired many new characters such as dynamic, openness,distribution and information uncertainty.The processing mode of application systems is more complicated than ever.For example,it requires application systems to have more community processing ability,interactive ability,distributed processing ability and collaborative ability.Accordingly the research and development of the computer application system transited from client/server information processing system into distributed collaborative processing system based on Web.Especially in the environment where the information and resources are highly distributed,the accomplishment of complicated tasks is dependent more on the resources coordination,information sharing and coordinator collaboration.The collaboration is one aspect of the group behavior and its goal is to provide a optimal method to utilize the resource through the information interaction and to solve the task which couldn't be accomplished by each coordinator alone and get the more total benefits than the sum of each benefit.The collaboration problem is the important one for distributed tasks processing.This paper surveys,the research and application status of distributed collaborative models and several representative architectures of distributed collaborative processing are proposed.However,the existing problems and the future researching direction are presented.     

An assignment method for IPUs in distributed systems

In a distributed system,one of the most important thing is to establish an assignment method for distributing tasks.It is assumed that a distributed system does not have a central administrator,all independent processing units in this system want to cooperate for the best results,but they cannot know the conditions of one another,So in order to undertake the tasks in admirable proportions,they have to adjust their undertaking tasks only by selt-learning.In this paper,the performance of this system is analyzed by Markov chains,and a robust method of self-learning for independent processing units in this kind of systems is presented.This method can lead the tasks of the system to be distributed very well among all the independent processing units,and can also be used to solve the general assignment problem.     

A formal framework of multi-agent systems with requirement/service cooperative style

Adopting three kinds of speech acts:request,promise,and inform,this paper analyses the interaction among agents in a kind of multi-agent systems with requirements/services cooperation style(MASr-s).The paper gives the objective model the theoretic satisfaction conditions of three kinds of speech acts in MASr-s.The formal definition of MASr-s has been presented.To evaluate concrete implementation architecture and mechanism of the variant MASr-s.including client/server computing architecture and mechanism,a spectrum of MASr-s has been proposed,which captures direct request/passive service mechanism,direct request /active service mechanism,indirect request/active service mechanism,and peer to-peer request /service mechanism.The Spectrum shows a thread to improve traditional client/server computing.     

Synthesizing Distributed Protocol Specifications from a UML State Machine Modeled Service Specification

The object-oriented paradigm is widely applied in designing and implementing communication systems.Unified Modeling Language(UML) is a standard language used to model the design of object-oriented systems.A protocol state machine is a UML adopted diagram that is widely used in designing communication protocols.It has two key attractive advantages over traditional finite state machines:modeling concurrency and modeling nested hierarchical states.In a distributed communication system,each entity of the system has its own protocol that defines when and how the entity exchanges messages with other communicating entities in the system.The order of the exchanged messages must conform to the overall service specifications of the system.In object-oriented systems,both the service and the protocol specifications are modeled in UML protocol state machines.Protocol specification synthesis methods have to be applied to automatically derive the protocol specification from the service specification.Otherwise,a time-consuming process of design,analysis,and error detection and correction has to be applied iteratively until the design of the protocol becomes error-free and consistent with the service specification.Several synthesis methods are proposed in the literature for models other than UML protocol state machines,and therefore,because of the unique features of the protocol state machines,these methods are inapplicable to services modeled in UML protocol state machines.In this paper,we propose a synthesis method that automatically synthesizes the protocol specification of distributed protocol entities from the service specification,given that both types of specifications are modeled in UML protocol state machines.Our method is based on the latest UML version(UML2.3),and it is proven to synthesize protocol specifications that are syntactically and semantically correct.As an example application,the synthesis method is used to derive the protocol specification of the H.323 standard used in Internet calls.     

Adaptive Resource Allocation for Service-Based Systems

Due to its major advantages, service-oriented architecture (SOA) has been adopted in various distributed systems, such as web services, grid computing systems, utility computing systems and cloud computing systems. These systems are referred as service-based systems (SBS). In order to effectively use these systems in various applications, one major challenge which must be addressed is to manage the quality of services (QoS) to satisfy users’ requirements. In SBS, multiple services are often hosted by the same server and compete for the limited system resources of the server, such as CPU-time, memory and network bandwidth. In addition, service compositions, resource status of servers, workflow priorities and QoS requirements are usually dynamically changing in runtime. Hence, it is necessary to have effective techniques to allocate the system resources to each service provided by a server in order to satisfy the QoS requirements of multiple workflows in SBS. In this paper, a resource allocation approach is presented to adaptively allocating the system resources of servers to their services in runtime in order to satisfy one of the most important QoS requirements, the throughput, of multiple workflows in SBS.     

可伸缩TAGS

In a distributed Web server system where tasks are unpreemptible,the most important issue for improving quality of service(QoS)is how to realize fairness and reduce average slow down.In this paper we present an algorithm named Scalable TAGS by integrating Central Queue algorithm and Task Assignment by Guessing Size(TAGS),together with its performance analysis,system parameter setting algorithm subject to fairness require-ment,and optimal grouping method.     

Synthesizing Service Composition Models on the Basis of Temporal Business Rules

Transformational approaches to generating design and implementation models from requirements can bring effectiveness and quality to software development. In this paper we present a framework and associated techniques to generate the process model of a service composition from a set of temporal business rules. Dedicated techniques including path-finding,branching structure identification and parallel structure identification are used for semi-automatically synthesizing the process model from the semantics-equivalent Finite State Automata of the rules. These process models naturally satisfy the prescribed behavioral constraints of the rules. With the domain knowledge encoded in the temporal business rules,an executable service composition program,e.g.,a BPEL program,can be further generated from the process models. A running example in the e-business domain is used for illustrating our approach throughout this paper.     

Analysis and case study on multi-dimensional scalability of the Internet architecture

This paper presents the definition of multi-dimensional scalability of the Internet architecture, and puts forward a mathematical method to evaluate Internet scalability based on a variety of constraints. Then, the method is employed to study the Internet scalability problem in performance, scale and service scalability. Based on the examples, theoretical analysis and experimental simulation are conducted to address the scalability issue. The results show that the proposed definition and evaluation method of multi-dimensional Internet scalability can effectively evaluate the scalability of the Internet in every aspect, thus providing rational suggestions and methods for evaluation of the next generation Internet architecture.     

Software-as-a-service （SaaS）： perspectives and challenges

Software-as-a-service （SaaS） has received significant attention recently as one of three principal components of cloud computing, and it often deals with applications that run on top of a platform-as-a-service （PaaS） that in turn runs on top of infrastructure-as-a-service （IaaS）. This paper provides an overview of SaaS including its architecture and major technical issues such as customization, multi-tenancy architecture, redun- dancy and recovery mechanisms, and scalability. Specifically, a SaaS system can have architecture relating to a database-oriented approach, middleware-oriented approach, service-oriented approach, or PaaS-oriented ap- proach. Various SaaS customization strategies can be used from light customization with manual coding to heavy customization where the SaaS system and its underlying PaaS systems are customized together. Multi-tenancy architecture is an important feature of a SaaS and various trade-offs including security isolation, performance, and engineering effort need to be considered. It is important for a SaaS system to have multi-level redundancy and recovery mechanisms, and the SaaS system needs to coordinate these with the underlying PaaS system. Finally, SaaS scalability mechanisms include a multi-level architecture with load balancers, automated data migration, and software design strategies.     

Design of multimedia conference control system based on SIP

As various multimedia communication services are increasingly required by Intemet users, several signaling protocols have been proposed for the efficient control of multimedia communication services. However, the model and architecture of multimedia conferencing are several. This paper first introduces some SIP multimedia conferencing architectures, and their advantages, disadvantages and performance. According to a centralized multimedia conferencing model, feasible system architecture is constructed, which can support middle scale multimedia conference. Then it analyzes the key technologies in centralized SIP multimedia conference, such as media server design and audio mixing, Then, a multimedia conference system is designed based on SIP. The SIP-based control mechanism for achieving the scalability has been designed in details. Finally, the system＇s performance is evaluated and discussed.     

Massive Storage Systems

To accommodate the explosively increasing amount of data in many areas such as scientific computing and e-Business, physical storage devices and control components have been separated from traditional computing systems to become a scalable, intelligent storage subsystem that, when appropriately designed, should provide transparent storage interface, effective data allocation, flexible and efficient storage management, and other impressive features. The design goals and desirable features of such a storage subsystem include high performance, high scalability, high availability, high reliability and high security. Extensive research has been conducted in this field by researchers all over the world, yet many issues still remain open and challenging. This paper studies five different online massive storage systems and one offline storage system that we have developed with the research grant support from China. The storage pool with multiple network-attached RAIDs avoids expensive store-and-forward data copying between the server and storage system, improving data transfer rate by a factor of 2-3 over a traditional disk array. Two types of high performance distributed storage systems for local-area network storage are introduced in the paper. One of them is the Virtual Interface Storage Architecture (VISA) where VI as a communication protocol replaces the TCP/IP protocol in the system. VISA's performance is shown to achieve better than that of IP SAN by designing and implementing the vSCSI (Vl-attached SCSI) protocol to support SCSI commands in the VI network. The other is a fault-tolerant parallel virtual file system that is designed and implemented to provide high I/O performance and high reliability. A global distributed storage system for wide-area network storage is discussed in detail in the paper, where a Storage Service Provider is added to provide storage service and plays the role of user agent for the storage system. Object based Storage Systems not only store data but also adopt the attributes and methods of objects that encapsulate the data. The adaptive policy triggering mechanism (APTM), which borrows proven machine learning techniques to improve the scalability of object storage systems, is the embodiment of the idea about smart storage device and facilitates the self-management of massive storage systems. A typical offline massive storage system is used to backup data or store documents, for which the tape virtualization technology is discussed. Finally, a domain-based storage management framework for different types of storage systems is presented in the paper.     

WWW Business Applications Based on the Cellular Model

A cellular model based on the Incrementally Modular Abstraction Hierarchy(IMAH)is a novel model that can represent the architecture of and changes in cyberworlds,preserving invariants from a general level to a specific one.We have developed a data processing system called the Cellular Data System(CDS).In the development of business applications,you can prevent combinatorial explosion in the process of business design and testing by using CDS.In this paper,we have first designed and implemented wide-use algebra on the presentation level.Next,we have developed and verified the effectiveness of two general business applications using CDS:1)a customer information management system,and 2)an estimate system.     

A concept of dynamically reconfigurable real-time vision system for autonomous mobile robotics

This paper describes specific constraints of vision systems that are dedicated to be embedded in mobile robots. If PC-based hardware architecture is convenient in this field because of its versatility, flexibility, performance, and cost, current real-time operating systems are not completely adapted to long processing with varying duration, and it is often necessary to oversize the system to guarantee fail-safe functioning. Also, interactions with other robotic tasks having more priority are difficult to handle. To answer this problem, we have developed a dynamically reconfigurable vision processing system, based on the innovative features of Cleopatre real-time applicative layer concerning scheduling and fault tolerance. This framework allows to define emergency and optional tasks to ensure a minimal quality of service for the other subsystems of the robot, while allowing to adapt dynamically vision processing chain to an exceptional overlasting vision process or processor overload. Thus, it allows a better cohabitation of several subsystems in a single hardware, and to develop less expensive but safe systems, as they will be designed for the regular case and not rare exceptional ones. Finally, it brings a new way to think and develop vision systems, with pairs of complementary operators.     

NONH:A New Cache-Based Coherence Protocol for Linked List Structure DSM System and Its Performance Evaluation

The management of memory coherence is an important problem in distributed shared memory(DSM)system.In a cache-based coherence DSM system using linked list structure,the key to maintaining the coherence and improving system performance is how to manage the owner in the linked list.This paper presents the design of a new management protocol-NONH(New-Owner New-Head)and its performance evaluation.The analysis results show that this protocol can improve the scalability and performence of a coherent DSM system using linked list.It is also suitable for managing the cache coherency in tree-like hierarchical architecture.     

A mobile-agent-based approach to software coordination in the HOOPE system

Software coordination is central to the construction of large-scale high-performance distributed applications with software services scattered over the decentralized Internet. In this paper, a new mobile-agent-based architecture is proposed for the utilization and coordination of geographically distributed computing resources. Under this architecture, a user application is built with a set of software agents that can travel across the network autonomously. These agents utilize the distributed resources and coordinate with each other to complete their task. This approach' s advantages include the natural expression and flexible deployment of the coordination logic, the dynamic adaptation to the network environment and the potential of better application performance. This coordination architecture, together with an object-oriented hierarchical parallel application framework and a graphical application construction tool, is implemented in the HOOPE environment, which provides a systematic support for the de     

Development of Wafer Warehouse Management System for Semiconductor Manufacturing Foundry Supply Chain

Efficiency of supply chains management mostly depends on the process coordination and information integration between the supply chain companies.The well-known integrated circuit design houses,the wafer fabrication industries, and the integrated circuit packaging/testing business has together formed a contiguous supply chain from materials to system in Taiwan during the past decades.Logistic management of the wafer hence becomes the key linkage in the semiconductor foundry supply chain.The objective of this paper is to develop the wafer warehouse management system for global wafer logistics.Current operations for wafer logistics management are firstly reviewed. The system requirements are analyzed by the model-driven business transformation approach.The business operation model and the platform-independent solution architecture for the wafer logistics management are constructed.A prototype information system is also developed for validation.Results of this research can improve the effectiveness and efficiency in wafer logistics management for the semiconductor foundry supply chain.     

A component mining approach to incubate Grid services in object-oriented legacy systems

This paper describes an approach for Grid service component mining in object-oriented legacy systems, applying Software clustering, architecture recovery, program slicing and wrapping techniques to decompose a legacy system, analyse the concerned components and integrate them into a Grid environment. The resulting components with core legacy code function in a Grid service framework.     

System of Grid Resource Monitoring Service

Resource monitoring is a key component in grid system. It can help understanding the performance limits and forecasting the failure of the system, advice in the scheduling and configuration of grid application and so on. This paper puts forward a system of grid resource monitoring service which is based on MDS （Monitoring and Discovery Service）, which achieves real-time monitoring and the visualization of historical monitoring data for computing nodes in grid by Globus Toolkits. It introduces the design ideas of this service system, presents its architecture, and discusses its supports for low delay, low performance affection, scalability and manageability.     

Editorial: Internetware in Motion

The Internet provides a global open infrastructure for exchanging and sharing of various resource all over the world. The rapid development and wide application of the Internet makes it a new mainstream platform to use, develop, deploy and execute software systems and applications. With the vision of "Internet as a computer", many technical initiatives such as pervasive computing, grid computing, service computing and cloud computing emerges on this open and dynamic environment. In order to support the various new application styles and accommodate the fundamental change of the underlying infrastructure, many specific software technologies such as service-oriented architecture are proposed for current practices. While these technologies are useful and widely accepted, they have not formed a systematic solution as matured as the object-oriented technology, as a uniformed software methodology and technology system is yet to be developed.