bluuebunny/crossref_metadata_2025 huggingface dataset:
Group consistency model which separates the intra-group consistency maintenance from the inter-group consistency maintenance in large scale DSM systems
Authors: Li Qun , Ji Hua , Xie Li
Published: October 2004

According to the characteristics of large scale network computing systems, we proposed a group consistency model based on the concept of group to construct a DSM system. The novel model can use different inter-group and intra-group consistencies and lend itself to flexible, easily-managable, and application-suitable DSM in large scale systems. A group consistency model, which applies entry consistency among groups and lazy release consistency in a group, together with its implementation policy is discussed in this paper. It employs write-update and multiple-writer protocols in a group, and thus facilitates the simultaneous read and write in a group. The suitable protocols eliminate the false sharing and reduce the data acquiring time in a group. Furthermore, the inter-group consistency also suits the features of data sharing among groups and transmits the data modifications originated from a group in bulk to reduce the network traffic. In the end, an example using group consistency model is given and the trivial group consistency is discussed.
Load distribution and balancing support in a workstation-based distributed system
Authors: Arredondo D. , Errecalde M. , Piccoli F. , Printista M. , Gallard R. , Flores s.
Published: October 2004

In distributed systems, load distribution and balancing are primary functions addressed to improvements on system performance and additional user comfort. Incoming task allocation and remote process execution are main responsibilities of a well designed system to achieve such performance improvements. Both aspects involve a number of non trivial tasks.As a basement for further automatic system decision in a distributed environment, this paper propose a user-supervised processor allocation scheduler, shows which information should be collected and when and how to collect and disseminate it to support the user decision.The main problems to be considered when implementing remote process execution are discussed and a design for an alternative system attempting to solve these problems is also shown.
The controlled cell transfer capability
Authors: Van Luinen Steven , Budrikis Zigmantas L. , Cantoni Antonio
Published: October 2004

A Controlled Cell Transfer (CCT) capability has been proposed to ITU for definition in Recommendation I.371. The CCT capability, if accepted, will bring the number of ATM transfer layer capabilities to five. The other four capabilities being Deterministic Bit Rate (DBR), Statistical Bit Rate (SBR), ATM Block Transfer (ABT) and Available Bit Rate (ABR). It is believed that this capability will endow the ATM network with LAN like service over the wide area. In this article, we discuss the features and mechanisms of the proposed CCT capability. We also discuss the applications that CCT is targeted at supporting and present results of simulation studies, highlighting the advantages of CCT.
IFIP
Authors: Davis Gordon B.
Published: October 2004

New business functions and new academic disciplines have been proposed in the past, and they have not survived. In the past 50 years, information systems has emerged as a business function with a chief information officer (CIO) and information systems (with various names such as MIS) as an academic field. The business function shows some signs of instability, such as short longevity for CIOs and extensive outsourcing. The academic field often expresses uncertainty in the face of rapid changes in its domain of knowledge and criticism from other disciplines. What is the prognosis for the future?
Through A Glass, Darkly
Authors: Glass Robert L.
Published: October 2004

"Through a glass, darkly" is a biblical description of the imperfect way in which we see the world around us.
Using representation clauses as an operating system interface
Authors: Nyberg Karl A.
Published: October 2004

A set of Ada® packages and programs for performing system accounting under the Ultrix™ operating system on the VAX™ using VADS™ are described. These programs provide for the billing of timesharing customers based on amount of connect time and quantity of CPU usage. Interactions at the operating system level are accomplished through the use of representation specifications. A description of the changes required when the operating system data structures were modified by the operating system manufacturer during an upgrade are also presented.
A new process migration algorithm
Authors: Richmond Michael , Hitchens Michael
Published: October 2004

Process migration has been advocated as a means of improving the load balancing and reliability of distributed systems. This paper reviews the major design issues for process migration algorithms, such as the amount of state information to be transferred and times at which information should be transferred. This examination demonstrates the existence of a process migration algorithm which has not previously been documented. After describing existing algorithms, the new algorithm is given and compared to the other algorithms. The new algorithm promises better load balancing results while avoiding residual dependencies
The novel algorithm for determining the reachability in acyclic Petri nets
Authors: Kostin A. E.
Published: October 2004

A novel algorithm for determining the reachability of a marking in acyclic Petri nets is proposed. For this algorithm, a Petri net is represented in the matrix form, with a given pair of initial and target markings. The algorithm is based on the creation of a temporal ordering relation for transition firings and on using this relation for determining the shortest sequence of transition firings transforming the initial marking into the target one. By solving the fundamental equation of the Petri net, the algorithm determines initially whether the target marking is reachable from the given initial marking, and, in case it is, produces the shortest sequence of transition firings which transforms the initial marking into the target one.
The impact of Ada and object-oriented design in NASA Goddard's Flight Dynamics Division
Authors: Waligora Sharon , Bailey John , Stark Mike
Published: October 2004

This paper presents the highlights and key findings of 10 years of use and study of Ada and object-oriented design in NASA Goddard's Flight Dynamics Division (FDD). In 1985, the Software Engineering Laboratory (SEL) began investigating how the Ada language might apply to FDD software development projects. Although they began cautiously using Ada on only a few pilot projects, they expected that, if the Ada pilots showed promising results, the FDD would fully transition its entire development organization from FORTRAN to Ada within 10 years. However, 10 years later, the FDD still produced 80 percent of its software in FORTRAN and had begun using C and C++, despite positive results on Ada projects. This paper presents the final results of a SEL study to quantify the impact of Ada in the FDD, to determine why Ada has not flourished, and to recommend future directions regarding Ada. Project trends in both languages are examined as are external factors and cultural issues that affected the infusion of this technology. The detailed results of this study were published in a formal study report [1] in March of 1995. This paper supersedes the preliminary results of this study that were presented at the Eighteenth Annual Software Engineering Workshop in 1993 [2].
Emerging opportunities for theoretical computer science
Authors: Aho Alfred V. , Johnson David S. , Karp Richard M. , Kosaraju S. Rao , McGeoch Catherine C. , Papadimitriou Christos H. , Pevzner Pavel
Published: October 2004

The principles underlying this report can be summarized as follows:1. A strong theoretical foundation is vital to computer science.2. Theory can be enriched by practice.3. Practice can be enriched by theory.4. If we are guided by (2) and (3), the value, impact, and funding of theory will be enhanced.In order to achieve a greater synergy between theory and application, and to sustain and expand on the remarkable successes of Theory of Computing (TOC), we consider it essential to increase the impact of theory on key application areas. This requires additional financial resources in support of theory, and closer interaction between theoreticians and researchers in other areas of computer science and in other disciplines.The report does not make a detailed assessment of the overall state of theoretical computer science or fully chronicle the achievements of this field. Instead, it has the specific objective of recommending ways to harness these remarkable achievements for the solution of challenging problems emerging from new developments such as the information superhighway.Section 1 describes the events leading up to this report and delineates the report's objectives. Section 2 establishes the context for the report. It traces the history of TOC, describes the impact that TOC has achieved in the areas of core theory and fundamental algorithms, points out the differences between these areas and application-oriented theory, and calls for an intensified effort to bring the methods of TOC to bear on applications. It then goes on to define the four main categories into which our recommen- dations fall: building bridges between theory and applications, algorithm engineering, communication, and education. Section 3 discusses some specific opportunities for stimulating interactions between TOC and applied areas. Section 4 proposes an applied research initiative,
Information Access in a Globally Distributed Environment
, which identifies an exciting current technological area that we believe presents challenging opportunities for excellent theoretical work. Section 5 proposes a second applied research initiative,
The Algorithmic Stockroom
, that would exploit and extend the body of theoretical knowledge in the field of algorithms. Section 6 proposes a broadening in graduate education with two purposes in mind: to better prepare theoreticians to interact creatively with practitioners, and to provide future practitioners with the background they will need to benefit from this exchange.
Strategic directions in research in theory of computing
Authors: Condon Anne , Fich Faith , Frederickson Greg N. , Goldberg Andrew V. , Johnson David S. , Loui Michael C. , Mahaney Steven , Raghavan Prabhakar , Savage John E. , Selman Alan L. , Shmoys David B.
Published: October 2004

This report focuses oll two core areas of theory of computing: discrete algorithms and computational complexity theory. The report reviews the purposes and goals of theoretical research, summarizes selected past and recent achievements, explains the importance of sustaining core research, and identifies promising opportunities for filture research. Some research opportunities build bridges between theory of computing and other areas of computer science, and other science and engineering disciplines.
Fast restoration of real-time communication service from component failures in multi-hop networks
Authors: Han Seungjae , Shin Kang G.
Published: October 2004

For many applications it is important to provide communication services with guaranteed timeliness and fault-tolerance at an acceptable level of overhead. In this paper, we present a scheme for restoring real-time channels, each with guaranteed timeliness, from component failures in multi-hop networks. To ensure fast/guaranteed recovery,
backup channels
are set up a
priori
in addition to each
primary channel
. That is, a
dependable real-time connection
consists of a primary channel and one or more backup channels. If a primary channel fails, one of its backup channels is activated to become a new primary channel. We describe a protocol which provides an integrated solution to the failure-recovery problem (i.e., channel switching, resource re-allocation, ...). We also present a resource sharing method that significantly reduces the overhead of backup channels. The simulation results show that good coverage (in recovering from failures) can be achieved with about 30% degradation in network utilization under a reasonable failure condition. Moreover, the fault-tolerance level of
each
dependable connection can be controlled, independently of other connections, to reflect its criticality.
Active bridging
Authors: Alexander D. Scott , Shaw Marianne , Nettles Scott M. , Smith Jonathan M.
Published: October 2004

Active networks accelerate network evolution by permitting the network infrastructure to be programmable, on a per-user, per-packet, or other basis. This programmability must be balanced against the safety and security needs inherent in shared resources.This paper describes the design, implementation, and performance of a new type of network element, an Active Bridge. The active bridge can be reprogrammed "on the fly", with loadable modules called switchlets. To demonstrate the use of the active property, we incrementally extend what is initially a programmable buffered repeater with switchlets into a self-learning bridge, and then a bridge supporting spanning tree algorithms. To demonstrate the agility that active networking gives, we show how it is possible to upgrade a network from an "old" protocol to a "new" protocol on-the-fly. Moreover, we are able to take advantage of information unavailable to the implementors of either protocol to validate the new protocol and fall back to the old protocol if an error is detected. This shows that the Active Bridge can protect itself from some algorithmic failures in loadable modules.Our approach to safety and security favors static checking and prevention over dynamic checks when possible. We rely on strong type checking in the Caml language for the loadable module infrastructure, and achieve respectable performance. The prototype implementation on a Pentium-based HP Netserver LS running Linux with 100 Mbps Ethernet LANS achieves ttcp throughput of 16 Mbps between two PCs running Linux, compared with 76 Mbps unbridged. Measured frame rates are in the neighborhood of 1800 frames per second.
End-to-end Internet packet dynamics
Authors: Paxson Vern
Published: October 2004

We discuss findings from a large-scale study of Internet packet dynamics conducted by tracing 20,000 TCP bulk transfers between 35 Internet sites. Because we traced each 100 Kbyte transfer at both the sender and the receiver, the measurements allow us to distinguish between the end-to-end behaviors due to the different directions of the Internet paths, which often exhibit asymmetries. We characterize the prevalence of unusual network events such as out-of-order delivery and packet corruption; discuss a robust receiver-based algorithm for estimating "bottleneck bandwidth" that addresses deficiencies discovered in techniques based on "packet pair"; investigate patterns of packet loss, finding that loss events are not well-modeled as independent and, furthermore, that the distribution of the duration of loss events exhibits infinite variance; and analyze variations in packet transit delays as indicators of congestion periods, finding that congestion periods also span a wide range of time scales.
Network performance effects of HTTP/1.1, CSS1, and PNG
Authors: Nielsen Henrik Frystyk , Gettys James , Baird-Smith Anselm , Prud'hommeaux Eric , Lie Håkon Wium , Lilley Chris
Published: October 2004

We describe our investigation of the effect of persistent connections, pipelining and link level document compression on our client and server HTTP implementations. A simple test setup is used to verify HTTP/1.1's design and understand HTTP/1.1 implementation strategies. We present TCP and real time performance data between the libwww robot [27] and both the W3C's Jigsaw [28] and Apache [29] HTTP servers using HTTP/1.0, HTTP/1.1 with persistent connections, HTTP/1.1 with pipelined requests, and HTTP/1.1 with pipelined requests and deflate data compression [22]. We also investigate whether the TCP Nagle algorithm has an effect on HTTP/1.1 performance. While somewhat artificial and possibly overstating the benefits of HTTP/1.1, we believe the tests and results approximate some common behavior seen in browsers. The results confirm that HTTP/1.1 is meeting its major design goals. Our experience has been that implementation details are very important to achieve all of the benefits of HTTP/1.1.For all our tests, a pipelined HTTP/1.1 implementation outperformed HTTP/1.0, even when the HTTP/1.0 implementation used multiple connections in parallel, under all network environments tested. The savings were at least a factor of two, and sometimes as much as a factor of ten, in terms of packets transmitted. Elapsed time improvement is less dramatic, and strongly depends on your network connection.Some data is presented showing further savings possible by changes in Web content, specifically by the use of CSS style sheets [10], and the more compact PNG [20] image representation, both recent recommendations of W3C. Time did not allow full end to end data collection on these cases. The results show that HTTP/1.1 and changes in Web content will have dramatic results in Internet and Web performance as HTTP/1.1 and related technologies deploy over the near future. Universal use of style sheets, even without deployment of HTTP/1.1, would cause a very significant reduction in network traffic.This paper does not investigate further performance and network savings enabled by the improved caching facilities provided by the HTTP/1.1 protocol, or by sophisticated use of range requests.
Consistent overhead byte stuffing
Authors: Cheshire Stuart , Baker Mary
Published: October 2004

Byte stuffing is a process that transforms a sequence of data bytes that may contain 'illegal' or 'reserved' values into a potentially longer sequence that contains no occurrences of those values. The extra length is referred to in this paper as the overhead of the algorithm.To date, byte stuffing algorithms, such as those used by SLIP [RFC1055], PPP [RFC1662] and AX.25 [ARRL84], have been designed to incur low average overhead but have made little effort to minimize worst case overhead.Some increasingly popular network devices, however, care more about the worst case. For example, the transmission time for ISM-band packet radio transmitters is strictly limited by FCC regulation. To adhere to this regulation, the practice is to set the maximum packet size artificially low so that no packet, even after worst case overhead, can exceed the transmission time limit.This paper presents a new byte stuffing algorithm, called Consistent Overhead Byte Stuffing (COBS), that tightly bounds the worst case overhead. It guarantees in the worst case to add no more than one byte in 254 to any packet. Furthermore, the algorithm is computationally cheap, and its average overhead is very competitive with that of existing algorithms.
A framework for robust measurement-based admission control
Authors: Grossglauser Matthias , Tse David
Published: October 2004

Measurement-based Admission Control (MBAC) is an attractive mechanism to concurrently offer Quality of Service (QoS) to users, without requiring a-priori traffic specification and on-line policing. However, several aspects of such a system need to be clearly understood in order to devise robust MBAC schemes. Through a sequence of increasingly sophisticated stochastic models, we study the impact of parameter estimation errors, of flow arrival and departure dynamics, and of estimation memory on the performance of an MBAC system.We show that a
certainty equivalence
assumption, i.e., assuming that the measured parameters are the real ones, can grossly compromise the target performance of the system. We quantify the improvement in performance as a function of the memory size of the estimator and a more conservative choice of the certainty-equivalent parameters. Our results yield valuable new insight into the performance of MBAC schemes, and represent quantitative guidelines for the design of robust schemes.
Effective bandwidths for a class of non Markovian fluid sources
Authors: Kontovasilis Kimon , Mitrou Nikolas
Published: October 2004

This paper proves the existence of and explicitly determines effective bandwidths for a class of non Markovian fluid source models, featuring multiple data-transmission rates and arbitrary distributions for the times these rates are sustained. The investigated models cover considerably more traffic profiles than the usual Markovian counterparts and have reduced state-space requirements. The effective bandwidth, as a function of the asymptotic loss probability decay rate, is implicitly derivable by the requirement that the spectral radius of an appropriate nonnegative matrix be equal to unity. The effective bandwidth function is shown to be, either strictly increasing, or constant and equal to the mean rate. Sources of the second kind, which are characterized, generalize the notion of 'CBR' traffic. Furthermore, a study for the limiting effective bandwidth, towards a loss-less environment, is undertaken; it is shown that the limiting value may, under some fully identified restrictions on the source behavior, be less than the source's peak rate. Under those restrictions, a source may have reduced bandwidth requirements, even if it features a large peak rate.
An Interview with Phillip D. Farr
Authors: Kappelman Leon
Published: October 2004

As Director of Management Information Services, Phillip D. Farr is responsible for the information technology (IT) function at American Petrofina, Inc. (FINA). His responsibilities include long-term planning, as well as day-to-day operations. FINA (AMEX: FI) is a Dallas-based company engaged in crude oil and natural gas exploration and production; petroleum products refining, marketing, and transportation; as well as the manufacturing and marketing of petrochemicals and plastics. Organized in 1956, FINA is part of an international group of companies affiliated with Petrofina S.A. headquartered in Brussels, Belgium. In 1995 FINA had revenues over $3.6 billion, employed nearly 2700 people, and had over 2700 company-branded service stations.Mr. Farr has more than 25 years experience in the information systems (IS) field and 9 years in his present position. He has a degree in mathematics and physics from East Texas State University and has done graduate work at Harvard Business School and the University of Virginia. He is a member of the Society for Information Management (SIM), the Data Processing Management Association (DPMA), and the Greater Dallas Chamber of Commerce. He is a past chair of the Information Systems Committee of the American Petroleum Institute and of the Advisory Board of the Business Computer Information Systems Department at the University of North Texas.
Personal computer adventure games
Authors: Ju Edward , Wagner Christian
Published: October 2004

Personal computer adventure games, in which the player assumes the role of a fantasy character to pursue an adventure, have enjoyed enormous popularity and commercial success. Beyond their entertainment value, these games also have an educational value, training users to become better problem solvers in the game domain and probably beyond.In order to understand better this type of game and determine its potential use for managerial training, we analyzed adventure games with respect to three issues. First, what makes a computer simulation an adventure game; second, what makes such a game enjoyable and challenging; and finally, how well does such a game facilitate learning? In search of answers, we analyzed a number of adventure games to determine game structures, and completed a small empirical study in which subjects played a game and had to answer both content and preference related questions.Overall, our analysis reconfirmed people's liking of adventure games. Players seem to enjoy the games' story and interface, and are challenged by the game tasks. Players also learn from gaming; yet levels of learning vary widely, based on the type of knowledge to be conveyed. Fact learning proved to be easiest; plan learning and learning of negative knowledge, the hardest.
PRISM
Authors: Welch Lonnie R.
Published: October 2004

This paper presents a process for the reengineering of computer-based control systems, and describes tools that automate portions of the process. The intermediate representation (IR) for capturing features of computer-based systems during reverse engineering is presented. A novel feature of the IR is that it incorporates the control system software architecture, a view that enables information to be captured at five levels of granularity: the program level, the task level, the package level, the subprogram level, and the statement level. A reverse engineering toolset that constructs the IR from Ada programs, displays the IR, and computes metrics for concurrency, communication and object-orientedness is also presented.
Protecting internal state variables from subclasses
Authors: Dorchak Susan Fife , Guild S. Rollins
Published: October 2004

The use of child packages to encapsulate derived tagged types and their operations should protect the state variables of the parent type that are to be manipulated by the parent operations alone. This protection can be achieved through the declaration of a data component of a limited record type, previously declared with no attributes and an access type discriminant that visibly points to an incomplete definition. The details of the data component (either scalar or composite, depending on application), whose full type declaration is in the parent package body, is accessible only through the discriminant from within the package body. This mechanism provides full information hiding of the details and maximum protection of the contents of those instance variables.
Fast, approximate synthesis of fractional Gaussian noise for generating self-similar network traffic
Authors: Paxson Vern
Published: October 2004

Recent network traffic studies argue that network arrival processes are much more faithfully modeled using statisticallyself-similarprocesses instead of traditional Poisson processes [LTWW94, PF95]. One difficulty in dealing with self-similar models is how to efficiently synthesize traces (sample paths) corresponding to self-similar traffic. We present a fast Fourier transform method for synthesizing approximate self-similar sample paths for one type of self-similar process, Fractional Gaussian Noise, and assess its performance and validity. We find that the method is as fast or faster than existing methods and appears to generate close approximations to true self-similar sample paths. We also discuss issues in using such synthesized sample paths for simulating network traffic, and how an approximation used by our method can dramatically speed up evaluation of Whittle's estimator forH, the Hurst parameter giving the strength of long-range dependence present in a self-similar time series.
Authentication using minimally trusted servers
Authors: Chen Liqun , Gollmann Dieter , Mitchell Chris J.
Published: October 2004

A number of key distribution protocols using multiple authentication servers, where a minority of them may be untrustworthy, have recently been proposed. This paper analyses the problem of key distribution using minimally trusted multiple servers, and presents a new protocol. In this protocol, as long as all servers do not collude to defraud the clients, either a session key (not known to any server) is successfully established, or the protocol fails in such a way that the clients are aware that it has failed, i.e. the protocol works in a situation where the servers are 'minimally trusted'.
Review of: Metamathematics, Machines, and Gödels Proof by N. Shankar
Authors: Puxang K.
Published: October 2004

This book, first published in 1994, is derived from the author's 1986 Ph.D dissertation, one of the main goals of which was to gauge the usefulness of automatic theorem proving technology in constructing and verifying proofs. The proofs chosen for this task were Gödel's first incompleteness theorem and the Church-Rosser theorem of the lambda calculus. The theorem prover used was the Boyer-Moore theorem prover which can be obtained by ftp [1]. A manual for the prover has been published as [2]. The author gives a detailed account of the more important steps leading to the mechanized verification of proofs of these theorems. The theorem prover did not discover the proofs but checked definitions and lemmas (about 2000 for the incompleteness theorem and supplied by the author) that lead to the theorems.
Visualizing working sets
Authors: Markatos Evangelos P.
Published: October 2004

It is widely known that most applications exhibit locality of reference. That is, applications access only a subset of their pages during any phase of their execution. This subset of pages is usually called the
working set
of the application. In this note we present the working set of applications in pictorial form so that it can be easily viewed and understood. Based on these working set "pictures' we make observations about the size, the duration, and the regularity of the working sets of various applications. Our applications cover several domains, ranging from numerical applications, program development tools, CAD simulations, and database applications. Our results suggest that most numerical and some database applications have regular access patterns and good locality of reference. Although most database and program development applications seem to have little locality of reference, careful observations at the appropriate granularity reveal regular and sometimes periodic access patterns.
Semantics subsystem in distributed OS formalization generating system
Authors: He Yanxiang , Zhang Jianping , Cooley Donald H. , Chen Li
Published: October 2004

The Distributed OS Formalization Generating System (DOSFGS) described in this paper consists of a grammar subsystem DOSGS and a semantics subsystem DOSSS. DOSGS is a form of Context Free Grammar. DOSSS is a semantics system with an operating set. DOSGS uses the semantics subsystem DOSSS to automatically generate a simulation version of a distributed OS in three steps:
abstraction, description,
and
refinement.
DOSSS is the central component of DOSFGS. This paper discusses the data structures, operating set and functions, and working principles defining DOSSS.
Distributed and fault tolerant systems (session summary)
Authors: Gargaro Anthony , Locke Douglass , Volz Richard
Published: October 2004

The workshop's objectives for the sessions were:1. Discuss experiences and issues implementing Annex E and providing tool support for developing distributed programs.2. Examine issues implied by allowing the distributed replication of programs.
Developing reusable multi-tasking components using object-oriented techniques in Ada 95
Authors: de Bondeli Patrick
Published: October 2004

Since 1985, we have undertaken extensive works on concurrent system development methodology and their systematic implementation in Ada. In 1990-1991, this resulted in the presentation of the CODE-TOP (COncurrent system DEvelopment using Transformations Of Predicate-transition nets) methodology [1][2]. Starting from this basis, we later developed a framework of components, using OO techniques, which are reusable to implement in Ada 95 any type exporting synchronization / communication properties [3].This leads us to propose, as a theme for this workshop, the identification, development, and implementation in Ada 95 of general purpose reusable components for concurrent systems. By "general purpose", we mean that these components are not specialized in any specific domain as, for example, communication, or guidance and control systems. This proposal enters perfectly within the goals that were stated in the "Call for Participation" and is more specifically related to the two following goals :"Identify the benefits and impacts of using object-oriented programming in multi-tasking real-time systems";"Explore the use of Ada 95 in developing multi-tasking components that are resilient to software design errors and hardware failures".In section 2, we briefly expose the state of our works, which we already quoted.In section 3, we propose to consider the different possible kinds of reusable multi-tasking components in Ada 95. On one kind of components our works could be a good starting point for discussion.
T-SMART—task-safe, minimal Ada realtime toolset
Authors: Dobbing Brian , Richard-Foy Marc
Published: October 2004

This paper describes T-SMART, an Ada83 executive and toolset for the production of safety critical and hard real time applications. T-SMART consists of three main integrated parts:- Ada runtime executive audited to DO-178B standard for use in safety-critical systems- Traditional Ada compilation system tools such as Compiler, Binder and Debugger- Tools to support program verification, such as schedulability and coverage analysis.The existing toolset is suitable for building safety-critical and hard real time systems in Ada83 with some extensions and enforced coding style. The extensions have been designed to be compatible with the recent revision of the Ada language (Ada95) in order to ease the transition (both for the vendor who must audit the runtime executive, and for the user who must certify the application) when the Ada95 safety-critical market is eventually established.Although such toolsets are not uncommon, the significant differentiator is that the runtime executive has undergone the most stringent independent auditing to DO-178B standard, making it suitable for formal certification. Use of this toolset in actual safety-critical applications lays to rest the view that Ada tasking cannot be used in this market sector, and so provides valuable input to the evolution of the Safety and Security Annex in Ada95, which currently prohibits the use of Ada tasking.
Object-oriented real-time systems using a hybrid distributed model of Ada 95's built-in DSA capability (distributed systems annex-E) and CORBA
Authors: Moody Scott Arthur
Published: October 2004

This paper reports on the issues in design and development of Object Oriented Real-Time Distributed Systems using Ada 95. The paper is broken into the following parts: First, one of the general distributed real-time problems is introduced as it fits the domain within Boeing. Next, prototype solutions to the distributed capabilities are introduced including the new technologies present in Ada-95 through DSA (Distributed Systems Annex-E)[2] and extended with CORBA (Common Object Request Broker Architecture) capabilities[1]. Many issues are addressed with adoption and use of these technologies especially applicable as they relate to custom fine-tuned solutions used today to solve real-time constraints. As the various distributed solutions provide different strengths, a combination of the capabilities provides an attractive option. A hybrid distributed capability composed of DSA and CORBA has been developed and is discussed as it relates to the seamless introduction with the Ada language. Finally a set of research issues are raised.
Implementing CIFO using Ada 95 and POSIX
Authors: Powers Richard D.
Published: October 2004

Many people are interested in reducing the cost of development for military systems through reuse of existing software. One of the issues associated with supporting reuse of software is the need to support application interfaces. With the upgrade of the Ada programming language, many vendor's existing interfaces may change or become obsolete. In order to support legacy software as it is moved from Ada 83 to Ada 95, it is necessary to have a way to replace the application interfaces with a minimal impact on the legacy software.This paper describes a study to evaluate the possibility of supporting legacy software based on the Texas Instruments F-16 Modular Mission Computer Ada Compilation System (MACS) on a different target, using the features of Ada[?] and POSIX to implement the MACS-specific Application Programmer Interface (API). The majority of the MACS API was based on the Association for Computing Machinery (ACM) Ada Run- Time Environment Working Group (ARTEWG) Catalogue of Interface Features and Options (CIFO)[?]. The organization of this paper follows the same organization as the CIFO. The author assumes that the available Ada 95 compiler supports the Systems Programming and Real-Time annexes. The following CIFO entries were not implemented in the MACS:• Two Stage Task Suspension• Blackboards• Broadcasts• Mutuall Exclusive Access to Shared Data• Memory Management (though Ada 95 defines a similar package)
Using compliance notation to verify Ada tasking
Authors: Tombs D. J.
Published: October 2004

Tasking is the most important-aspect of Ada not addressed by existing verification systems. The DRA Compliance Notation allows a subset of Ada to be embedded in a engine supported by Z. We propose incorporating a reduced tasking model into the Notation.
Is North American IS research different from European IS research?
Authors: Evaristo J. Roberto , Karahanna Elena
Published: October 2004

Diversity, whether in terms of research methodologies or reference disciplines, enriches and benefits a field of research. If, on the other hand, this diversity inhibits the sharing of research and knowledge between communities with different intellectual heritages, loss of synergy and research opportunities for both communities may result. This study identifies similarities and differences between North American and European research in terms of theoretical bases and research methodologies by analyzing doctoral dissertation research. Results show that European MIS research is predominantly qualitative and non-empirical conceptual whereas North American MIS research is predominantly quantitative and empirical. Furthermore, research in Europe is influenced considerably by computer science and artificial intelligence whereas research in North America has more behavioral and managerial roots. A comparison across a five-year period shows that this gap is narrowing.
How can CASE help?
Authors: Jankowski David
Published: October 2004

One important role of a CASE tool is to serve as a methodology companion --- to assist an analyst in the creation of documentation passed to succeeding phases of the life cycle and to guide the analyst through a particular systems development methodology. While many vendors claim their CASE products supports a particular methodology, the actual level of support varies greatly from one CASE tool to another and, for a particular tool, the level of support varies among the rules of the methodology.The feasibility of using CASE to provide automated checking for the rules of structured analysis is presented within the context of a framework for examining CASE methodology support. Two popular CASE tools are compared against a feasibility benchmark by examining system specifications created using the tools. The results indicate that methodologically consistent specifications are more likely to be achieved when the methodology support provided by the CASE tool is as rigorous as possible.
Reinforcement of TCP error recovery for wireless communication
Authors: Samaraweera Nihal K. G. , Fairhurst Godred
Published: October 2004

When a wireless link forms a part of a network, the rate of packet loss due to link noise may be considerably higher than observed in a modern terrestrial network. This paper studies TCP performance over a range of link environments and highlights the advantage of recent modifications to TCP (e.g. SACK, New-Reno) for wireless communications. It also identifies two key issues which impact the performance of TCP over error prone links: TCP's reliance on timers to recover from a failed retransmission cycle, and TCP's inability to separate congestion packet loss from other types of packet loss. A solution to the first issue is identified and analysed by simulation, and the factors affecting the second issue are outlined.
Implementation of event handling in GNA95GP
Authors: Kuang Shan , George K. M. , Li Lan
Published: October 2004

GNAT Ada 95 Graphics Package (GNA95GP) is a 2D graphics library that supports graphics application development in Ada 95. It provides support for 2D drawing, event handling and storage of graphics primitives. This paper addresses the implementation of the event handling module of GNA95GP under Windows 3.1. Using this event handling module, an user can write interactive programs under PC environment in Ada 95 language. This event handling module is the result of an attempt to develop an event handling package using Microsoft Windows functions and Ada 95 programming language features. This paper describes event handling and its implementation in GNA95GP. Similar to other graphics packages such as GKS, SRGP, and PHIGS, event handling is an important part in GNA95GP.
A course in software reuse with Ada 95
Authors: Yu Huiming
Published: October 2004

Courses in software reuse based on Ada have been taught for several years in Department of Computer Science at North Carolina A&T State university [2][5][6]. The course materials have been updated and adopted for Ada 95 under a curriculum development grant from the Defense Information System Agency. The new course forms a semester-long undergraduate course titled "Software Reuse with Ada 95".In this course software reuse levels, general criteria, and software development with reuse are overviewed. Software development for reuse and object-oriented design techniques that support reuse are taught. Ada 95's object-oriented features and how to integrate these features to develop reusable artifacts are examined. Reuse library and management techniques are discussed. Students are trained as designers, implementers and clients. They practice the object oriented software development process by implementing a team project.
Using Ada to teach programming language design concepts
Authors: Bagert Donald J.
Published: October 2004

The undergraduate Concepts of Programming Languages course at Texas Tech University is part of an eight-course software engineering-related sequence in the undergraduate curriculum. Previous classes in this sequence make it both easy and natural to discuss software engineering concepts such as software reuse and program verification in this course.This paper discusses research into a revision of this course so that it is primarily centered on the Ada 95 programming language. The robustness and elegant design of Ada make it deal for such a class. Under a grant, a textbook and an instructor's guide have been developed for the Ada 95 portion of the lecture component, and were used at Texas Tech University during the Fall of 1996. The lecture notes and other materials were well-received, and the course was very successful, with an increase in exam, homework, program, and overall course averages (up by over 12%).
A comparative analysis of groupware application protocols
Authors: Pendergast Mark O.
Published: October 2004

Two of the most difficult problems faced by developers of synchronous groupware applications are the handling of multiple session connections and the maintenance of replicated data. Protocols and algorithms to solve these problems have evolved over the years as developers gained experience and network standards were developed and enriched. This paper analyzes the efficiency of three common application level protocols used for the development of groupware systems. These include central sequencing, distributed operations, and independent-immutable objects. In order to perform the analysis, nine measures of network and processor efficiency were developed. The result of the analysis showed the independent object method to be superior in overall efficiency. Central sequencing is recommended for applications that are not conducive to the use of independent objects.
How to break fraud-detectable key recovery
Authors: Pfitzmann Birgit , Waidner Michael
Published: October 2004

Fraud detection for software key recovery schemes means that, without knowing the session key, a third party can verify whether the correct session key could be recovered. This concept and a construction by so-called binding data was introduced by Verheul et al. at Eurocrypt '97 to provide for dishonest users that make simple modifications to messages, e.g., delete the key recovery information, and manipulate the recipient's software such that it decrypts messages even if the key recovery information is incorrect.We show how to break their general construction within their model, in particular without using any other encryption system or any pre-established shared secrets.We conclude that the concept of binding data does not improve the security of software key recovery but illustrates once more its fundamental problem: it does not improve an authorized third party's ability to eavesdrop on serious criminals.
Optimizing throughout in a workstation-based network file system over a high bandwidth local area network
Authors: Faber Theodore
Published: October 2004

This paper describes methods of optimizing a client/server network file system to advantage of high bandwidth local area networks in a conventional distributed computing environment. The environment contains hardware that removes network and disk bandwidth bottlenecks. The remaining bottlenecks at clients include excessive context switching, inefficient data translation, and cumbersome data encapsulation methods. When these are removed, the null-write performance of a current implementation of Sun's Network File System improves by 30%. A prototype system including a high speed RAM disk demonstrates an 18% improvement in overall write throughput. The prototype system fully utilizes the available peripheral bandwidth of the server.
Planning management of multiagent-based distributed open
Authors: He Yanxiang , Cooley Donald H. , Zhang Jianping
Published: October 2004

This paper examines planning management problems in a Multiagent-based Distributed Open Computing Environment Model (MDOCEM). We first introduce the meaning of planning management in MDOCEM. We then present a formal method to describe the associated task partition problems, and give a heuristic algorithm which gives an approximate optimum solution. Finally the task coordination and integration of execution results are discussed.
Best-effort versus reservations
Authors: Breslau Lee , Shenker Scott
Published: October 2004

Using a simple analytical model, this paper addresses the following question: Should the Internet retain its best-effort-only architecture, or should it adopt one that is reservation-capable? We characterize the differences between reservation-capable and best-effort-only networks in terms of application performance and total welfare. Our analysis does not yield a definitive answer to the question we pose, since it would necessarily depend on unknowable factors such as the future cost of network bandwidth and the nature of the future traffic load. However, our model does reveal some interesting phenomena. First, in some circumstances, the amount of incremental bandwidth needed to make a best-effort-only network perform as well as a reservation capable one diverges as capacity increases. Second, in some circumstances reservation-capable networks retain significant advantages over best-effort-only networks, no matter how cheap bandwidth becomes. Lastly, we find bounds on the maximum performance advantage a reservation-capable network can achieve over best-effort architectures.