Coordinating complex decision support activities across distributed applications

Knowledge-based technologies have been applied successfully to automate planning and scheduling in many problem domains. Automation of decision support can be increased further by integrating task-specific applications with supporting database systems, and by coordinating interactions between such tools to facilitate collaborative activities. Unfortunately, the technical obstacles that must be overcome to achieve this vision of transparent, cooperative problem-solving are daunting. Intelligent decision support tools are typically developed for standalone use, rely on incompatible, task-specific representational models and application programming interfaces (API's), and run on heterogeneous computing platforms. Getting such applications to interact freely calls for platform independent capabilities for distributed communication, as well as tools for mapping information across disparate representations. Symbiotics is developing a layered set of software tools (called NetWorks! for integrating and coordinating heterogeneous distributed applications. he top layer of tools consists of an extensible set of generic, programmable coordination services. Developers access these services via high-level API's to implement the desired interactions between distributed applications

CLICKLESS MOUSE INTERACTIVITY FOR TOURISM WEBSITE

Clickless Mouse Interactivityfor Tourism Website is a study of mouse interactivity which does not involve any mouse clicking to navigate, highlight, select or getting the properties of a link. Alternative mouse interactivity will be proposed to replace double-click, single-click, right-click, dragging to highlighting and drag and drop. A prototype based on a tourism website is developed to support both clicking and clickless interactivities. Experiment will be carried out on end-users to study the effect of clickless on usability of the website. The hypothesis that clickless mouse interactivity enhances the usabilityof a tourist website is tested

U/PC: un patrón arquitectónico para aplicaciones colaborativas

Los sistemas colaborativos pertenecen al área de investigación llamada CSCW (“Computer-Supported Cooperative Work”). Estos sistemas apoyan a grupos de personas trabajando en equipo, con el fin de alcanzar metas comunes. Un aspecto fundamental en todo proceso de colaboración es la comunicación, y aunque todos los sistemas siguen el mismo patrón arquitectónico, la falta de una definición explícita del patrón hace que sea imposible el reuso de soluciones en este ámbito. Es por eso que en el presente artículo se presenta el patrón arquitectónico U/PC (Users/Processes Communication) que modela los mecanismos de comunicación en los sistemas colaborativos, brindando una solución al problema antes mencionado.Eje: Ingeniería de softwareRed de Universidades con Carreras en Informática (RedUNCI

U/PC: un patrón arquitectónico para aplicaciones colaborativas

Los sistemas colaborativos pertenecen al área de investigación llamada CSCW (“Computer-Supported Cooperative Work”). Estos sistemas apoyan a grupos de personas trabajando en equipo, con el fin de alcanzar metas comunes. Un aspecto fundamental en todo proceso de colaboración es la comunicación, y aunque todos los sistemas siguen el mismo patrón arquitectónico, la falta de una definición explícita del patrón hace que sea imposible el reuso de soluciones en este ámbito. Es por eso que en el presente artículo se presenta el patrón arquitectónico U/PC (Users/Processes Communication) que modela los mecanismos de comunicación en los sistemas colaborativos, brindando una solución al problema antes mencionado.Eje: Ingeniería de softwareRed de Universidades con Carreras en Informática (RedUNCI

Un modelo de coordinación cliente-servidor, de apoyo a la construcción de aplicaciones colaborativas portables

En la actualidad existe una gran variedad de plataformas de apoyo al desarrollo de aplicaciones colaborativas, que trabajan bajo una arquitectura cliente-servidor [Chabert 98, Guerrero 98, Licea 98, Trevor 97]. Estas poseen un alto grado de incompatibilidad entre ellas, lo cual produce una fuerte dependencia de la aplicación cliente, hacia el servidor usado. Debido a esto, las capacidades de las aplicaciones están sometidas a la funcionalidad permitida por el servidor. Esto entorpece el avance de las investigaciones y de los desarrollos, ya que para resolver un problema, antes hay que resolver un conjunto de problemas asociados (sistemas de percepción, manejadores de eventos, etc.). La solución obvia a estos problemas pasa por la portabilidad, por eso que en este trabajo se presenta un modelo de coordinación, como referencia para la construcción de aplicaciones colaborativas portables.Eje: Ingeniería de softwareRed de Universidades con Carreras en Informática (RedUNCI

Un modelo de coordinación cliente-servidor, de apoyo a la construcción de aplicaciones colaborativas portables

En la actualidad existe una gran variedad de plataformas de apoyo al desarrollo de aplicaciones colaborativas, que trabajan bajo una arquitectura cliente-servidor [Chabert 98, Guerrero 98, Licea 98, Trevor 97]. Estas poseen un alto grado de incompatibilidad entre ellas, lo cual produce una fuerte dependencia de la aplicación cliente, hacia el servidor usado. Debido a esto, las capacidades de las aplicaciones están sometidas a la funcionalidad permitida por el servidor. Esto entorpece el avance de las investigaciones y de los desarrollos, ya que para resolver un problema, antes hay que resolver un conjunto de problemas asociados (sistemas de percepción, manejadores de eventos, etc.). La solución obvia a estos problemas pasa por la portabilidad, por eso que en este trabajo se presenta un modelo de coordinación, como referencia para la construcción de aplicaciones colaborativas portables.Eje: Ingeniería de softwareRed de Universidades con Carreras en Informática (RedUNCI

Domain Computing: The Next Generation of Computing

Computers are indispensable in our daily lives. The first generation of computing started the era of human automation computing. These machine’s computational resources, however, were completely centralized in local machines. With the appearance of networks, the second generation of computing significantly improved data availability and portability so that computing resources could be efficiently shared among the networks. The service-oriented third generation of computing provided functionality by breaking down applications into services, on-demand computing through utility and cloud infrastructures, as well as ubiquitous accesses from wide-spread geographical networks. Services as primary computing resources are far spread from lo- cal to worldwide. These services loosely couple applications and servers, which allows services to scale up easily with higher availability. The complexity of locating, utilizing and optimizing computational resources becomes even more challenging as these resources become more available, fault-tolerant, scalable, better per- forming, and spatially distributed. The critical question becomes how do applications dynamically utilize and optimize unique/duplicate/competitive resources at runtime in the most efficient and effective way without code changes, as well as providing high available, scalable, secured and easy development services. Domain computing proposes a new way to manage computational resources and applications. Domain computing dy- namically manages resources within logic entities, domains, and without being bound to physical machines so that application functionality can be extended at runtime. Moreover, domain computing introduces domains as a replacement of a traditional computer in order to run applications and link different computational resources that are distributed over networks into domains so that a user can greatly improve and optimize the resource utilization at a global level. By negotiating with different layers, domain computing dynamically links different resources, shares resources and cooperates with domains at runtime so applications can more quickly adapt to dynamically changing environments and gain better performance. Also, domain computing presents a new way to develop applications which are resource stateless based. In this work, a prototype sys- tem was built and the performance of its various aspects has been examined, including network throughput, response time, variance, resource publishing and subscription, and secured communications

ATOM : a distributed system for video retrieval via ATM networks

The convergence of high speed networks, powerful personal computer processors and improved storage technology has led to the development of video-on-demand services to the desktop that provide interactive controls and deliver Client-selected video information on a Client-specified schedule. This dissertation presents the design of a video-on-demand system for Asynchronous Transfer Mode (ATM) networks, incorporating an optimised topology for the nodes in the system and an architecture for Quality of Service (QoS). The system is called ATOM which stands for Asynchronous Transfer Mode Objects. Real-time video playback over a network consumes large bandwidth and requires strict bounds on delay and error in order to satisfy the visual and auditory needs of the user. Streamed video is a fundamentally different type of traffic to conventional IP (Internet Protocol) data since files are viewed in real-time, not downloaded and then viewed. This streaming data must arrive at the Client decoder when needed or it loses its interactive value. Characteristics of multimedia data are investigated including the use of compression to reduce the excessive bit rates and storage requirements of digital video. The suitability of MPEG-1 for video-on-demand is presented. Having considered the bandwidth, delay and error requirements of real-time video, the next step in designing the system is to evaluate current models of video-on-demand. The distributed nature of four such models is considered, focusing on how Clients discover Servers and locate videos. This evaluation eliminates a centralized approach in which Servers have no logical or physical connection to any other Servers in the network and also introduces the concept of a selection strategy to find alternative Servers when Servers are fully loaded. During this investigation, it becomes clear that another entity (called a Broker) could provide a central repository for Server information. Clients have logical access to all videos on every Server simply by connecting to a Broker. The ATOM Model for distributed video-on-demand is then presented by way of a diagram of the topology showing the interconnection of Servers, Brokers and Clients; a description of each node in the system; a list of the connectivity rules; a description of the protocol; a description of the Server selection strategy and the protocol if a Broker fails. A sample network is provided with an example of video selection and design issues are raised and solved including how nodes discover each other, a justification for using a mesh topology for the Broker connections, how Connection Admission Control (CAC) is achieved, how customer billing is achieved and how information security is maintained. A calculation of the number of Servers and Brokers required to service a particular number of Clients is presented. The advantages of ATOM are described. The underlying distributed connectivity is abstracted away from the Client. Redundant Server/Broker connections are eliminated and the total number of connections in the system are minimized by the rule stating that Clients and Servers may only connect to one Broker at a time. This reduces the total number of Switched Virtual Circuits (SVCs) which are a performance hindrance in ATM. ATOM can be easily scaled by adding more Servers which increases the total system capacity in terms of storage and bandwidth. In order to transport video satisfactorily, a guaranteed end-to-end Quality of Service architecture must be in place. The design methodology for such an architecture is investigated starting with a review of current QoS architectures in the literature which highlights important definitions including a flow, a service contract and flow management. A flow is a single media source which traverses resource modules between Server and Client. The concept of a flow is important because it enables the identification of the areas requiring consideration when designing a QoS architecture. It is shown that ATOM adheres to the principles motivating the design of a QoS architecture, namely the Integration, Separation and Transparency principles. The issue of mapping human requirements to network QoS parameters is investigated and the action of a QoS framework is introduced, including several possible causes of QoS degradation. The design of the ATOM Quality of Service Architecture (AQOSA) is then presented. AQOSA consists of 11 modules which interact to provide end-to-end QoS guarantees for each stream. Several important results arise from the design. It is shown that intelligent choice of stored videos in respect of peak bandwidth can improve overall system capacity. The concept of disk striping over a disk array is introduced and a Data Placement Strategy is designed which eliminates disk hot spots (i.e. Overuse of some disks whilst others lie idle.) A novel parameter (the B-P Ratio) is presented which can be used by the Server to predict future bursts from each video stream. The use of Traffic Shaping to decrease the load on the network from each stream is presented. Having investigated four algorithms for rewind and fast-forward in the literature, a rewind and fast-forward algorithm is presented. The method produces a significant decrease in bandwidth, and the resultant stream is very constant, reducing the chance that the stream will add to network congestion. The C++ classes of the Server, Broker and Client are described emphasizing the interaction between classes. The use of ATOM in the Virtual Private Network and the multimedia teaching laboratory is considered. Conclusions and recommendations for future work are presented. It is concluded that digital video applications require high bandwidth, low error, low delay networks; a video-on-demand system to support large Client volumes must be distributed, not centralized; control and operation (transport) must be separated; the number of ATM Switched Virtual Circuits (SVCs) must be minimized; the increased connections caused by the Broker mesh is justified by the distributed information gain; a Quality of Service solution must address end-to-end issues. It is recommended that a web front-end for Brokers be developed; the system be tested in a wide area A TM network; the Broker protocol be tested by forcing failure of a Broker and that a proprietary file format for disk striping be implemented

Engineering Automation for Reliable Software Interim Progress Report (10/01/2000 - 09/30/2001)

Prepared for: U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211The objective of our effort is to develop a scientific basis for producing reliable software that is also flexible and cost effective for the DoD distributed software domain. This objective addresses the long term goals of increasing the quality of service provided by complex systems while reducing development risks, costs, and time. Our work focuses on "wrap and glue" technology based on a domain specific distributed prototype model. The key to making the proposed approach reliable, flexible, and cost-effective is the automatic generation of glue and wrappers based on a designer's specification. The "wrap and glue" approach allows system designers to concentrate on the difficult interoperability problems and defines solutions in terms of deeper and more difficult interoperability issues, while freeing designers from implementation details. Specific research areas for the proposed effort include technology enabling rapid prototyping, inference for design checking, automatic program generation, distributed real-time scheduling, wrapper and glue technology, and reliability assessment and improvement. The proposed technology will be integrated with past research results to enable a quantum leap forward in the state of the art for rapid prototyping.U. S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-22110473-MA-SPApproved for public release; distribution is unlimited