3,424 research outputs found

    On Tunable Sparse Network Coding in Commercial Devices for Networks and Filesystems

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    Development of a client interface for a methodology independent object-oriented CASE tool : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Computer Science at Massey University

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    The overall aim of the research presented in this thesis is the development of a prototype CASE Tool user interface that supports the use of arbitrary methodology notations for the construction of small-scale diagrams. This research is part of the larger CASE Tool project, MOOT (Massey's Object Oriented Tool). MOOT is a meta-system with a client-server architecture that provides a framework within which the semantics and syntax of methodologies can be described. The CASE Tool user interface is implemented in Java so it is as portable as possible and has a consistent look and feel. It has been designed as a client to the rest of the MOOT system (which acts as a server). A communications protocol has been designed to support the interaction between the CASE Tool client and a MOOT server. The user interface design of MOOT must support all possible graphical notations. No assumptions about the types of notations that a software engineer may use can be made. MOOT therefore provides a specification language called NDL for the definition of a methodology's syntax. Hence, the MOOT CASE Tool client described in this thesis is a shell that is parameterised by NDL specifications. The flexibility provided by such a high level of abstraction presents significant challenges in terms of designing effective human-computer interaction mechanisms for the MOOT user interface. Functional and non-functional requirements of the client user interface have been identified and applied during the construction of the prototype. A notation specification that defines the syntax for Coad and Yourdon OOA/OOD has been written in NDL and used as a test case. The thesis includes the iterative evaluation and extension of NDL resulting from the prototype development. The prototype has shown that the current approach to NDL is efficacious, and that the syntax and semantics of a methodology description can successfully be separated. The developed prototype has shown that it is possible to build a simple, non-intrusive, and efficient, yet flexible, useable, and helpful interface for meta-CASE tools. The development of the CASE Tool client, through its generic, methodology independent design, has provided a pilot with which future ideas may be explored

    Creating a Distributed Programming System Using the DSS: A Case Study of OzDSS

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    This technical report describes the integration of the Distribution Subsystem (DSS) to the programming system Mozart. The result, OzDSS, is described in detail. Essential when coupling a programming system to the DSS is how the internal model of threads and language entities are mapped to the abstract entities of the DSS. The model of threads and language entities of Mozart is described at a detailed level to explain the design choices made when developing the code that couples the DSS to Mozart. To show the challenges associated with different thread implementations, the C++DSS system is introduced. C++DSS is a C++ library which uses the DSS to implement different types of distributed language entities in the form of C++ classes. Mozart emulates threads, thus there is no risk of multiple threads accessing the DSS simultaneously. C++DSS, on the other hand, makes use of POSIX threads, thus simultaneous access to the DSS from multiple POSIX threads can happen. The fundamental differences in how threads are treated in a system that emulates threads (Mozart) to a system that make use of native-threads~(C++DSS) is discussed. The paper is concluded by a performance comparison between the OzDSS system and other distributed programming systems. We see that the OzDSS system outperforms ``industry grade'' Java-RMI and Java-CORBA implementations

    Life of occam-Pi

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    This paper considers some questions prompted by a brief review of the history of computing. Why is programming so hard? Why is concurrency considered an “advanced” subject? What’s the matter with Objects? Where did all the Maths go? In searching for answers, the paper looks at some concerns over fundamental ideas within object orientation (as represented by modern programming languages), before focussing on the concurrency model of communicating processes and its particular expression in the occam family of languages. In that focus, it looks at the history of occam, its underlying philosophy (Ockham’s Razor), its semantic foundation on Hoare’s CSP, its principles of process oriented design and its development over almost three decades into occam-? (which blends in the concurrency dynamics of Milner’s ?-calculus). Also presented will be an urgent need for rationalisation – occam-? is an experiment that has demonstrated significant results, but now needs time to be spent on careful review and implementing the conclusions of that review. Finally, the future is considered. In particular, is there a future

    Data Aggregation Tree Construction: Algorithms and Challenges

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    E-COMMERCE: A NEW BUSINESS MODEL FOR THE FOOD SUPPLY/DEMAND CHAIN

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    The use of electronic commerce for quality control and cost cutting efficiencies by the food and agricultural industries in the United States is the focus of this paper. The food industry engages in e-commerce through 1.) Internet shopping for consumers called business-to-consumer (B2C) e-commerce 2.) Business-to-business (B2B) Internet market discovery exchanges used by food suppliers at any point in the supply chain, and 3.) Business-to-business (B2B) relationships that reduce costs and increase efficiencies in the procurement, storage and delivery of food to retail stores or distribution centers. This third use of e-commerce is the most highly developed and widely adopted. It allows retailers to share information about consumers' purchases and preferences with food manufacturers and farmers and for tracking food products' characteristics, source, and movement from production to consumer. This circle of information allows high quality and consistent products to be consumed at lower prices. This paper is about the development of e-commerce in the food industry, the economic concepts and goals that it meets, and the changes it brings to the industry. E-commerce both fosters and demands vertical coordination. It favors consolidation of firms. It changes the business culture from one of adversarial relationships to one of cooperation and trust. It changes the historical supply chain into a supply/demand loop while it lowers the cost of food. Policy issues arise around monopoly power, privacy, a diminution of variety, and the demise of small, undercapitalized firms.Industrial Organization, Marketing,
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