Derivation of Test Cases for LAP-B from a LOTOS Specification

this paper, we show how this method has been applied to obtain test cases for LAP-B that are comparable, and in fact occasionally better, than those obtained by [KLPU][Kan]. Since TTCN is a common language for the spec- ification of test trees, the test cases obtained are written in TTCN (we should observe, however, that LOTOS itself appears to be adequate for the specification of test trees [Steen]). This technique appears to be valuable for conformance testing, at least until such time as the more formal approaches being developed by other authors become available (see Section 7). It makes it possible to extract test cases directly from (possibly standardized) formal descriptions, eliminating or reducing the importance of the interpretation of the informally specified standard. The formal specification is more complete and precise than the state tables and, unlike the latter, allows full formal treatment of the data part. For example, we shall show that automatic or semiautomatic generation of frame values appear to be possible by using the information contained in selection predicates

Integration of the White Sands Complex into a Wide Area Network

The NASA White Sands Complex (WSC) satellite communications facility consists of two main ground stations, an auxiliary ground station, a technical support facility, and a power plant building located on White Sands Missile Range. When constructed, terrestrial communication access to these facilities was limited to copper telephone circuits. There was no local or wide area communications network capability. This project incorporated a baseband local area network (LAN) topology at WSC and connected it to NASA's wide area network using the Program Support Communications Network-Internet (PSCN-I). A campus-style LAN is configured in conformance with the International Standards Organization (ISO) Open Systems Interconnect (ISO) model. Ethernet provides the physical and data link layers. Transmission Control Protocol and Internet Protocol (TCP/IP) are used for the network and transport layers. The session, presentation, and application layers employ commercial software packages. Copper-based Ethernet collision domains are constructed in each of the primary facilities and these are interconnected by routers over optical fiber links. The network and each of its collision domains are shown to meet IEEE technical configuration guidelines. The optical fiber links are analyzed for the optical power budget and bandwidth allocation and are found to provide sufficient margin for this application. Personal computers and work stations attached to the LAN communicate with and apply a wide variety of local and remote administrative software tools. The Internet connection provides wide area network (WAN) electronic access to other NASA centers and the world wide web (WWW). The WSC network reduces and simplifies the administrative workload while providing enhanced and advanced inter-communications capabilities among White Sands Complex departments and with other NASA centers

Standards as interdependent artifacts : the case of the Internet

Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2008.Includes bibliographical references.This thesis has explored a new idea: viewing standards as interdependent artifacts and studying them with network analysis tools. Using the set of Internet standards as an example, the research of this thesis includes the citation network, the author affiliation network, and the co-author network of the Internet standards over the period of 1989 to 2004. The major network analysis tools used include cohesive subgroup decomposition (the algorithm by Newman and Girvan is used), regular equivalence class decomposition (the REGE algorithm and the method developed in this thesis is used), nodal prestige and acquaintance (both calculated from Kleinberg's technique), and some social network analysis tools. Qualitative analyses of the historical and technical context of the standards as well as statistical analyses of various kinds are also used in this research. A major finding of this thesis is that for the understanding of the Internet, it is beneficial to consider its standards as interdependent artifacts. Because the basic mission of the Internet (i.e. to be an interoperable system that enables various services and applications) is enabled, not by one or a few, but by a great number of standards developed upon each other, to study the standards only as stand-alone specifications cannot really produce meaningful understandings about a workable system. Therefore, the general approaches and methodologies introduced in this thesis which we label a systems approach is a necessary addition to the existing approaches. A key finding of this thesis is that the citation network of the Internet standards can be decomposed into functionally coherent subgroups by using the Newman-Girvan algorithm.(cont.) This result shows that the (normative) citations among the standards can meaningfully be used to help us better manage and monitor the standards system. The results in this thesis indicate that organizing the developing efforts of the Internet standards into (now) 121 Working Groups was done in a manner reasonably consistent with achieving a modular (and thus more evolvable) standards system. A second decomposition of the standards network was achieved by employing the REGE algorithm together with a new method developed in this thesis (see the Appendix) for identifying regular equivalence classes. Five meaningful subgroups of the Internet standards were identified, and each of them occupies a specific position and plays a specific role in the network. The five positions are reflected in the names we have assigned to them: the Foundations, the Established, the Transients, the Newcomers, and the Stand-alones. The life cycle among these positions was uncovered and is one of the insights that the systems approach on this standard system gives relative to the evolution of the overall standards system. Another insight concerning evolution of the standard system is the development of a predictive model for promotion of standards to a new status (i.e. Proposed, Draft and Internet Standards as the three ascending statuses). This model also has practical potential to managers of standards setting organizations and to firms (and individuals) interested in efficiently participating in standards setting processes. The model prediction is based on assessing the implicit social influence of the standards (based upon the social network metric, betweenness centrality, of the standards' authors) and the apparent importance of the standard to the network (based upon calculating the standard's prestige from the citation network).(cont.) A deeper understanding of the factors that go into this model was also developed through the analysis of the factors that can predict increased prestige over time for a standard. The overall systems approach and the tools developed and demonstrated in this thesis for the study of the Internet standards can be applied to other standards systems. Application (and extension) to the World Wide Web, electric power system, mobile communication, and others would we believe lead to important improvements in our practical and scholarly understanding of these systems.by Mo-Han Hsieh.Ph.D

Seattle Pacific University Catalog 1992-1993

https://digitalcommons.spu.edu/archives_catalogs/1074/thumbnail.jp