bluuebunny/crossref_metadata_2025 huggingface dataset:
New challenges of systems development: a vision of the 90's
Authors: Lyytinen Kalle
Published: October 2004

During the 90's substantial changes will occur in systems development. Its design objects such as technological base, content and nature of information processes, and the organizational environment of information systems will undergo a rapid change. Its context including user populations, development tools, methods, and governing organizational form will become more complex and varied. Finally, its process features such as the espoused phase model and preferred organizational strategy will undergo a drastic change. All these changes point out that systems development will be radically different in the 90's and this will challenge the accepted wisdom of systems development. New methods and approaches must be developed, theoretical foundations established, organizational forms adopted, and system development skills will become more varied, dispersed and scarce.
Applications of computer-aided software engineering tools: survey of current and prospective users
Authors: Burkhard Donald L. , Jenster Per V.
Published: October 2004

Computer-Aided Software Engineering (CASE) tools are a relatively new technology that promises to have a significant impact on the way systems professionals develop and maintain information systems. This article reports on a study of the experience and expectations of current and prospective users of CASE tools. After an introductory discussion of CASE tools and their uses in an organizational context, the article presents the findings of a recent study of 46 organizations. The research focused on three major areas: expectations of CASE technology, reasons for acquiring CASE, and implementation issues. In conclusion, areas in need of further exploration are identified.
Facilitating connectivity in composite information systems
Authors: Wang Richard , Madnick Stuart E.
Published: October 2004

Timely access to multiple disparate databases which were independently developed and administered to produce composite information has become increasingly critical for organizations to gain competitive advantage. However, many inter-database problems such as inconsistency, ambiguity, and contradiction remain unresolved. This paper presents an approach for resolving these problems. The techniques employed in this approach include schema integration, inter-database tables, attribute subsetting, object hierarchies, and heuristic rules. Schema integration techniques resolve the incompatibilities among the databases at the schema level. Inter-database tables resolve the semantic inconsistency and concept granularity at the instance value level. The inter-database instance identification table identifies an instance across databases. Object hierarchies represent schemata as well as instances. Finally, heuristic rules are used to facilitate the construction of the inter-database instance identification table and the production of composite information.
A survey of fast packet switches
Authors: Jacob Andrew R.
Published: October 2004

With the advent of optical fiber and its large bandwidth, many services, such as packetized data, voice, and video, are now becoming available on physical transmission lines. The high data rates, however, have created a demand for high speed switching. Included among the different strategies which have been proposed are fully- and non-fully-connected switches, intelligent and non-intelligent switching nodes, broadcast capability, input and output queueing, input concentration and output reentry, and path preallocation. Most switches have a modular design. This paper compares the Knockout Switch [1], a switch designed by Jonathan Turner [2, 3], a switch designed by Joseph Hui and Edward Arthurs [4], and the Starlite Switch [5] based on the strategies listed above. Advantages and disadvantages are cited and conclusions have been made about the tradeoffs involved with operating conditions. Finally, future issues affecting fast packet switching are described.
Defining deadlock
Authors: Levine Gertrude Neuman
Published: October 2004

Deadlock has been widely studied in many fields of computer science, notably in communications, database, and operating systems. Perhaps because (at least one state called) deadlock is tractable, there exists extensive literature on the subject. Deadlock was apparently decisively defined over thirty years ago, with its characteristics and handlers. Yet, much of the literature remains inconsistent in its treatment of this anomaly.A more precise definition is clearly needed to distinguish between the different states that are termed deadlock. A classification of dead states is required to distinguish the causes and appropriate handlers for each. We introduce a model to structure our research.
Security enhancement for optimal strong-password authentication protocol
Authors: Lin Chih-Wei , Shen Jau-Ji , Hwang Min-Shiang
Published: October 2004

In 2001, Lin et al. proposed an optimal strong-password authentication protocol called the OSAP protocol. However, Chen and Ku pointed out that it is vulnerable to the stolen-verifier attack. In this paper, we shall propose an improved version of the OSAP protocol to enhance the security.
Asynchronous consensus protocol for the unreliable un-fully connected network
Authors: Wang S. C. , Yan K. Q. , Cheng C. F.
Published: October 2004

In order to achieve reliability in the distributed system, we need a mechanism to enable the system as a whole to continue to function despite the system has some faulty components. The
Consensus
problem is for the fault-free processors to cope with the faulty components and reach a common value from each other in the distributed system. Traditionally, the
Consensus
problems were solved in the
synchronous
network. Subsequently, Chandra and Toueg solved the Consensus problem with crash faulty processor in the
asynchronous
fully connected network in 1996. In this paper, we will solve the
Consensus
with dual failure mode (both crash fault and malicious fault) on communication links. The proposed protocol uses the minimum number of rounds of message exchange and can tolerate the maximum number of allowable faulty communication links to make each fault-free processor reach a common consensus value.
A novel disk queue to reduce disk I/O of messaging system
Authors: Wei Qingsong , Lu Xianliang , Ren Liyong , Zhou Xu
Published: October 2004

High reliability is the primary requirement for messaging system. Messaging system always utilizes disk queue to temporarily store waiting message. This paper analyzes by experiments and points out that disk queue I/O is the primary performance bottleneck in messaging system. To efficiently reduce disk I/O of messaging system, we propose a novel disk queue called SmartQ which utilizes pre-assigned continuous disk space to act as disk queue to reduce file manage overhead. Lazy Gathering Write and Sequential Grouping Prefetching polices of the SmartQ not only reduce the number of write and read, but also make full use of the disk bandwidth. Experiment shows that performance of the SmartQ is more than an order of magnitude higher than that of traditional disk queue.
High resolution timing with low resolution clocks and microsecond resolution timer for Sun workstations
Authors: Danzig Peter B. , Melvin Stephen
Published: October 2004

When tuning operating system and network code, profiling programs, analyzing message interarrival times, and accurately measuring device characteristics, a high resolution clock is often indispensable, as one cannot measure service time
distributions
without one. This note describes a microsecond clock that we designed and built for Sun 3 and Sun 4 workstations
1
. One can measure average service times without a high resolution clock. This paper explains how to measure average times with high precision in the absence of such a clock. We pose and answer the question: "how many measurements are needed to report timing data to three significant digits?"
An object oriented approach to virtual nodes: are package types an answer?
Authors: Goldsack S. J. , Alkinson C.
Published: October 2004

It is considered that a language supporting the construction of distributed systems must possess some structuring feature enabling the construction of components suitable to serve as units of network allocation and system reconfiguration. In some earlier studies of the distribution of Ada such units have been referred to as virtual nodes. [Hutcheon and Wellings 1988, Atkinson et al 1988].This paper discusses whether objects in the sense of object oriented systems are suitable to serve as virtual nodes (VNs). It then considers whether the introduction of package types could provide the kind of class object which is found in object oriented languages.In a system for the support of distribution there must also be support for network communications. The paper discusses briefly how network communication between objects can be provided.
Drawing Ada structure charts
Authors: Burkhard B , Lee M
Published: October 2004

This paper describes a method for drawing Ada structure charts and "with"ing trees. This method was used at GTE in developing the Ada version of a project management tool, TRACKER, for NOSC. The paper defines a set of symbols for various Ada entities. It further describes how these symbols can be combined to show nesting, packaging, "with"ing, generic instantiation, exported procedures and data, or any combination thereof. It also shows how visibility can be easily traced from the structure chart. Several examples are shown, including portions of the actual chart for Tracker. The paper concludes with a brief discussion of the benefits and limitations of this method, and compares it to those of Booch and Buhr.
A complete notation for Ada charts
Authors: Bishop J M
Published: October 2004

Several attempts have been made to define notations for diagrams that can represent the structure of an Ada program in terms of the interaction between its packages and tasks
1, 2, 3
. While handling the issue of visibility fairly well, none of these gives any guidance for the more difficult areas of Ada, such as generics, task creation and exceptions. The notation described here is complete. It employs a few carefully chosen features in a consistent way to construct an easily understandable chart of an Ada system. The notation is adaptable for use by hand or by computers with graphic capabilities.
From the chair
Authors: Sipior Janice C. , Schatzberg Laurie , Leidner Dorothy , Niederman Fred , Lending Diane
Published: October 2004

Greetings! Welcome to the new academic year. I hope it brings success and happiness to all of you. I would like to encourage you to consider sending a submission to the ACM-SIGMIS CPR (Computer Personnel Research) 2004 Conference to be held April 22-24, 2004 in Tucson, Arizona, USA. The theme of this year's conference is "Computer Personnel and Ethics in a Networked Environment."The submission deadline is October 27, 2003. Your participation is welcome! For more information, please contact the Conference Chair: Mohan Tanniru, University of Arizona, mtanniru@eller.arizona.edu or visit the conference website: http://www.eller.arizona.edu/mis/CPR2004.htmI would also like to encourage you to consider hosting a future SIGMIS CPR Conference. As you know, SIGMIS is committed to preserving and developing the CPR Conference. Let's all work to make it a continuing success!Please plan to attend the International Conference on Information and Knowledge Management (CIKM'03), which SIGMIS co-sponsors with ACM-SIGIR (Special Interest Group on Information Retrieval):

Conference
: International Conference on Information and Knowledge Management

Dates
: November 3-8, 2003

Location
: New Orleans, LA USA, Hotel Inter-Continental

Website
: http://www.cikm.org/2003

I would like to take this opportunity to thank Sajda Qureshi, University of Nebraska at Omaha, for her outstanding service as Program Chair of Knowledge Management for CIKM'02. Sajda has graciously agreed to continue in this role for CIKM'03. For additional information, you may contact her at: squreshi@ist.unomaha.edu.Finally, I would like to ask you to mark your calendar now for the "Third Annual ACM-SIGMIS Reception:"

Where
: International Conference on Information Systems (ICIS2003) Seattle, WA USA, Sheraton Seattle Hotel & Towers, Room 418/420

When
: 5:30 to 7:00 pm, Saturday, December 13, 2003

Who
: All ACM-SIGMIS members and their invited guests are welcome

Thank you for your continued support of SIGMIS. We encourage your comments and suggestions. Please feel free to contact any one of us.
Key predictors of the implementation of strategic information systems plans
Authors: Hartono Edward , Lederer Albert L. , Sethi Vijay , Zhuang Youlong
Published: October 2004

Strategic information systems planning (SISP) is the process of identifying a portfolio of computer-based applications that will assist an organization in executing its business plans and realizing its business goals. SISP is an important activity for information executives and top management. However, too often organizations fail to implement the recommendations from a SISP study. The SISP experiences of 105 experienced planners in this research used perceptual and objective measures to identify planning practices that predict the implementation of such plans. Deliberate planning for implementation during SISP presages that implementation whereas greater analysis of organizational needs may impede it.
Inductive methods for proving properties of programs
Authors: Manna Zohar , Ness Stephen , Vuillemin Jean
Published: October 2004

We have two main purposes in this paper. First, we clarify and extend known results about computation of recursive programs, emphasizing the difference between the theoretical and practical approaches. Secondly, we present and examine various known methods for proving properties of recursive programs. We discuss in detail two powerful inductive methods, computational induction and structural induction, illustrating their applications by various examples. We also briefly discuss some other related methods.

Our aim in this work is to introduce inductive methods to as wide a class of readers as possible and to demonstrate their power as practical techniques. We ask the forgiveness of our more theoretical-minded colleagues for our occasional choice of clarity over precision.
Program correctness methods and language definition
Authors: Ashcroft E. A.
Published: October 2004

The development of the method of proving correctness of programs is considered in relation to methods of defining programming languages. Informal methods are given for checking proposed adaptations of the correctness method to new programming languages. It is shown how correctness-formulae can be considered as semantic definitions of programs, and how Burstall's logical language definitions can be considered as correctness formulae.
Decision problems in computational models
Authors: Paterson Michael S.
Published: October 2004

Some of the assertions about programs which we might be interested in proving are concerned with correctness, equivalence, accessibility of subroutines and guarantees of termination. We should like to develop techniques for determining such properties efficiently and intelligently wherever possible. Though theory tells us that for a realistic programming language almost any interesting property of the behaviour is effectively undecidable, this situation may not be intolerable in practice. An unsolvability result just gives us warning that we may not be able to solve all of the problems we are presented with, and that some of the ones we can solve will be very hard.

In such circumstances it is very reasonable to try and determine necessary or sufficient conditions on programs for our techniques to be assured of success; however, in this paper we shall discuss a more qualitative, indirect, approach. We consider a range of more or less simplified computer models, chosen judiciously to exemplify some particular feature or features of computation. A demonstration of unsolvability in such a model reveals more accurately those sources which can contribute to unsolvability in a more complicated structure. On the other hand a decision procedure may illustrate a technique of practical use. It is our thesis that this kind of strategy of exploration can and will yield insight and practical advances in the theory of computation. Provided that the model retains some practical relevance, the dividends are the greater the nearer the decision problem lies to the frontier between solvability and unsolvability.
Translating recursion schemes into program schemes
Authors: Garland Stephen J. , Luckham David C.
Published: October 2004

Here and in a further paper [2] we study translations between schemes and related equivalence problems, i.e., problems of determining whether two schemes in a given class are equivalent. In particular, we are concerned with the question of developing methods for attacking these problems. It seems to us that some “general methods” ought to exist or, at least, a general form ought to be given to the existing “tricks”. In these papers we present four methods: applying the theory of formal languages, programming, measuring the complexity of a computation, and “cutting and pasting” (roughly speaking, the application of a method due to Rabin and Scott [8] to bound the search necessary to determine if two schemes will behave differently).

Although a few of the results are true for some general notion of scheme, we have nearly always had in mind, for the sake of illustration, just three specific classes of schemes: program schemes, program schemes augmented with counters, and recursively defined schemes. The greater part of the study is restricted to monadic schemes (i.e., schemes containing only functions and predicates of a single argument), and in the case of recursively defined schemes, we are concerned almost exclusively with the single variable monadic recursion schemes introduced by de Bakker and Scott in [1].
Properties preserved under recursion removal
Authors: Strong H. R. , Walker S. A.
Published: October 2004

In this paper we report research which is going on at present. Rather than presenting major results, we have selected a number of partial results and techniques in order to indicate a direction we think is promising. In the first section we review methods for converting a program with a calling structure involving recursion into one without such a structure. In the second section we discuss the separation of the aspects of control and storage in this recursion removal process. We show, by example, how the separation provides the possibility of preserving properties other than functional equivalence. These two sections provide a slight generalization of and complement work presented in the expository paper [S2]. In this third section we illustrate implications of invertibility of operations with respect to the recursion removal process. The central example of this section is the Ackerman functional, obtained by schematizing a version of the Ackerman function. With this example, we note that a recursion need not be convertible to a primitive recursion in order to be removable.
The Contour Model Lambda Calculus Machine
Authors: McGowan Clement
Published: October 2004

Much work has been done towards characterizing the semantics of block structured programming languages using the lambda calculus
[
2
]
. Johnston
[
3
]
recently introduced a cell-based approach, called the contour model, for specifying the execution semantics of such languages. This paper relates the two approaches by giving a contour model evaluator for compiled lambda expressions.

Section 2 gives the basic definitions needed from the lambda calculus to make the paper self-contained. Section 3 defines the Contour Model Lambda Calculus Machine (CMLCM). Unfortunately publication limitations preclude some worked examples which would greatly aid the reader's understanding. They will be provided in the talk itself and in an expanded version of this paper for the Tutorial Conference on Semantic Models of Computation. Section 4 outlines the structure of the proof of the CMLCM's correctness. And Section 5 is a set of concluding remarks on the significance of the CMLCM.
Correctness of a compiler for a Lisp subset
Authors: London Ralph L.
Published: October 2004

Excerpts of a proof of correctness of a running Lisp compiler for the PDP-10 computer are given. Included are the rationale for presenting this proof and a discussion of an actual extension of the proof to another compiler.
Operational semantics of programming languages
Authors: Wegner Peter
Published: October 2004

A framework is developed for the operational characterization of the semantics of computational formalisms such as programming languages, digital computers and automata. Operational semantics is contrasted with input-output semantics and it is shown that input-output semantics is inappropriate to the study of certain important implementation-dependent attributes of computational formalisms. Notions of equivalence are developed for a very general class of operational models called information structure models. The structure of proofs of compiler correctness and interpreter equivalence is discussed independently of the form of the states and state transitions of a specific interpreter. These techniques are then applied to defining a correctness criterion for block structure implementations and to correctness proofs of interpreters for block structure languages.
The definition and validation of the radix sorting technique
Authors: Lee John A. N.
Published: October 2004

Based on the formal definition techniques of Lucas et al
[1]
which have been applied to the description of programming languages, this paper defines the algorithm of radix sorting and develops a proof of its validity.
Formal development of correct algorithms
Authors: Jones C B
Published: October 2004

This paper contains the formal development of a correct algorithm from an implicit definition of the task to be performed. Each step of the development can be accompanied by a proof of its correctness. As well as ensuring the correctness of the final program, the structured development gives considerable insight into the algorithm and possible alternatives. The example used is a simplified form of the recognition algorithm due to Earley.
The equivalence of models of tasking
Authors: Berry Daniel M.
Published: October 2004

A technique for proving the equivalence of implementations of multi-tasking programming languages is developed and applied to proving the equivalence of the contour model and a multi-tasking version of the copy rule.
The “most recent” error
Authors: McGowan Clement L.
Published: October 2004

The notion of a general block structured programming language and the “most recent” evaluation strategy for such a language are formalized and their relationship investigated. Sufficient conditions for “most recent” correctness are obtained.
An invitation to Ada 2005
Authors: Leroy Pascal
Published: October 2004

Starting in 2000, the ISO technical group in charge of maintaining the Ada language has been looking into possible changes for the next revision of the standard, around 2005. Based on the input from the Ada community, it was felt that the revision was a great opportunity for further enhancing Ada by integrating new programming practices, e.g., in the OOP area; by providing new capabilities for embedded and high-reliability applications; and by remedying annoyances encountered during many years of usage of Ada 95. This led to the decision to make a substantive revision rather than a minor one. This paper outlines the standardization process and schedule, and presents a number of key improvements that are currently under consideration for inclusion in Ada 2005.
ACM SIGACT News distributed computing column 12
Authors: Rajsbaum Sergio
Published: October 2004

The Distributed Computing Column covers the theory of systems that are composed of a number of interacting computing elements. These include problems of communication and networking, databases, distributed shared memory, multiprocessor architectures, operating systems, verification, internet, and the web.This issue consists of the paper "Applications of Lattice Theory to Distributed Computing" by Vijay Garg, Neeraj Mittal, and Alper Sen. Many thanks to them for contributing to this issue.
Network security via private-key certificates
Authors: Davis Don , Swick Ralph
Published: October 2004

We present some practical security protocols that use private-key encryption in the public-key style. Our system combines a new notion of
private-key certificates
, a simple key-translation protocol, and key-distribution. These certificates can be administered and used much as public-key certificates are, so that users can communicate securely while sharing neither an encryption key nor a network connection.
A comparative study of two simple network file access models
Authors: Ghosh H. , Sreedhar S.
Published: October 2004

The authors have implemented two models for Remote File Access facilities in a network environment. This paper reviews the two implementations and compares their relative merits.
A note on Lamport's mutual exclusion algorithm
Authors: Woo Tai-Kuo
Published: October 2004

The Lamport's mutual exclusion exclusion algorithm, also known as the bakery algorithm, is very simple and easy to implement. However, the ticket numbers assigned to the processes wishing to enter the critical section can become indeterminately large. This paper resolves this problem by allowing the ticket numbers to move around a ring of length 2
N
, where
N
is the number of processes. The comparison of two ticket numbers is based the distance between them and their magnitudes.
Requisite skills for new MIS hires
Authors: Watson Hugh J. , Young Dale , Miranda Shaila , Robichaux Barry , Seerley Ron
Published: October 2004

Rapidly changing technology makes the information systems (IS) field a highly dynamic one. IS professionals must possess the requisite skills to be successful in this environment. At an April 1988 meeting of The University of Georgia - MIS Industry Advisory Board, twenty Board members ranked the skills that new MIS graduates should have if they seek an entry-level position as a programmer, systems analyst, or end-user support professional. Separate ranked lists were generated through Collaborative Work System (CWS) software so that required skills could be compared across entry-level positions. The findings provide insights about the changing needs of industry and implications for academic programs in colleges and universities.
Approximate fairness through differential dropping
Authors: Pan Rong , Breslau Lee , Prabhakar Balaji , Shenker Scott
Published: October 2004

Many researchers have argued that the Internet architecture would be more robust and more accommodating of heterogeneity if routers allocated bandwidth fairly. However, most of the mechanisms proposed to accomplish this, such as Fair Queueing [16, 6] and its many variants [2, 23, 15], involve complicated packet scheduling algorithms. These algorithms, while increasingly common in router designs, may not be inexpensively implementable at extremely high speeds; thus, finding more easily implementable variants of such algorithms may be of significant practical value. This paper proposes an algorithm called
Approximate Fair Dropping
(AFD), which bases its dropping decisions on the recent history of packet arrivals. AFD retains a simple forwarding path and requires an amount of additional state that is small compared to current packet buffers. Simulation results, which we describe here, suggest that the design provides a reasonable degree of fairness in a wide variety of operating conditions. The performance of our approach is aided by the fact that the vast majority of Internet flows are slow but the fast flows send the bulk of the bits. This allows a small sample of recent history to provide accurate rate estimates of the fast flows.
A solver for the network testbed mapping problem
Authors: Ricci Robert , Alfeld Chris , Lepreau Jay
Published: October 2004

Network experiments of many types, especially emulation, require the ability to map virtual resources requested by an experimenter onto available physical resources. These resources include hosts, routers, switches, and the links that connect them. Experimenter requests, such as nodes with special hardware or software, must be satisfied, and bottleneck links and other scarce resources in the physical topology should be conserved when physical resources are shared. In the face of these constraints, this mapping becomes an NP-hard problem. Yet, in order to prevent mapping time from becoming a serious hindrance to experimentation, this process cannot consume an excessive amount of time.In this paper, we explore this problem, which we call the
network testbed mapping problem
.We describe the interesting challenges that characterize it, and explore its applications to emulation and other spaces, such as distributed simulation. We present the design, implementation, and evaluation of a solver for this problem, which is in production use on the Netbed shared network testbed. Our solver builds on simulated annealing to find very good solutions in a few seconds for our historical workload, and scales gracefully on large well-connected synthetic topologies.
Large-scale network simulation techniques
Authors: Yaun Garrett R. , Bauer David , Bhutada Harshad L. , Carothers Christopher D. , Yuksel Murat , Kalyanaraman Shivkumar
Published: October 2004

Simulation of large-scale networks remains to be a challenge, although various network simulators are in place. In this paper, we identify fundamental issues for large-scale networks simulation, and porpose new techniques that address them. First, we exploit optimistic parallel simulation techniques to enable fast execution on inexpensive hyper-threaded, multiprocessor systems. Second, we provide a compact, light-weight implementation framework that greatly reduces the amount of state required to simulate large-scale network models. Based on the proposed techniques, we provide sample simulation models for two networking protocols: TCP and OSPF. We implement these models in a simulation environment ROSSNet, which is an extension to the previously developed optimistic simulator ROSS. We perform validation experoments for TCP and OSPF and present performance reuslts of our techniques by simulating OSPF and TCP on a large and realistic topology, such as AT&T's US network based on rocketfuel data.The end result of these innovations is that we are able to simulate million node network tolopgies using inexpensive commercial off-the-shelf hyper-threaded multiprocessor systems consuming less than 1.4 GB of RAM in total.
Topology discovery for public IPv6 networks
Authors: Waddington Daniel G. , Chang Fangzhe , Viswanathan Ramesh , Yao Bin
Published: October 2004

In just three decades the Internet has grown from a small experimental research network into a complex network of routers, switches, and hosts. Understanding the topology of such large scale networks is essential to the procurement of good architectural design decisions, particularly with respect to address allocation and distribution schemes.A number of techniques for IPv4 network topology already exist. Of these ICMP-based probing has shown to be most useful in determining router-level topologies of public networks. However, many of these techniques cannot be readily applied to IPv6 because of changes in the addressing scheme and ICMP behaviour. Furthermore, increases in the proliferation of equal-cost multi-path routing, and other forms of transient routing, indicate that traditional traceroute-based topology discovery approaches are becoming less effective in the Internet.This paper presents Atlas, a system that faciliates the automated capture of IPv6 network topology information from a single probing host. It describes the Atlas infrastructure and its data collection processes and discusses IPv6 network phenomena that must to be taken into account by the probing scheme. We also present some initial results from our probing of the 6Bone, currently the largest public IPv6 network. The results illustrate the effectiveness of the probing algorithm and also identify some trends in prefix allocation and routing policy.
A user-friendly self-similarity analysis tool
Authors: Karagiannis Thomas , Faloutsos Michalis , Molle Mart
Published: October 2004

The concepts of self-similarity, fractals, and long-range dependence (LRD) have revolutionized network modeling during the last decade. However, despite all the attention these concepts have received, they remain difficult to use by non-experts. This difficulty can be attributed to a relative complexity of the mathematical basis, the absence of a systematic approach to their application and the absence of publicly available software. In this paper, we introduce SELFIS, a comprehensive tool, to facilitate the evaluation of LRD by practitioners. Our goal is to create a stand-alone public tool that can become a reference point for the community. Our tool integrates most of the required functionality for an in-depth LRD analysis, including several LRD estimators. In addition, SELFIS includes a powerful approach to stress-test the existence of LRD, Using our tool, evidence are presented that the widely-used LRD estimators can provide misleading results. It is worth mentioning that 25 researchers have acquired SELFIS within a month of its release, which clearly demonstrates the need for such a tool.
CAVT
Authors: Welzl Michael , Mühlhäuser Max
Published: October 2004

We present CAVT, a simple yet powerful tool to visualize the behavior of congestion control mechanisms. Essentially being a simulator that builds upon the well-known Chiu/Jain vector diagrams, CAVT provides researchers, teachers and students with a new abstraction level that has already shown its value in practice.
Interprocess communication in real-time systems
Authors: Sorenson P. G.
Published: October 2004

A variety of solutions have been proposed for ensuring data integrity in nonreal-time systems (i.e. batch or on-line systems). A brief review is made of some of the techniques employed in these solutions. It is indicated why the data integrity problem is different in a real-time system than in a nonreal-time system. Two models of interprocess communication are presented and it is demonstrated that the models are sufficient to preserve data integrity in a real-time system.
An experimental implementation of the kernel/domain architecture
Authors: Spier Michale J. , Hastings Thomas N. , Cutler David N.
Published: October 2004

As part of its effort to periodically investigate various new promising concepts and techniques, the Digital Equipment Corporation has sponsored a research project whose purpose it was to effect a limited implementation of a protective operating system framework, based on the
kernel/domain
architecture which has increasingly been propounded in recent years.

The project was carried out in 1972, and its successful completion has led to a substantial number of observations and insights. This paper reports on the more significant ones, specifically: 1) the techniques used in mapping a conceptual model onto commercially available hardware (the PDP-11/45 mini-computer), 2) the domain's memory mapping properties, and their impact on programming language storage-class semantics, 3) this architecture's impact on the apparent simplification of various traditionally-complex operating systems monitor functions, and 4) the promise this architecture holds in terms of increased functional flexibility for future-generation geodesic operating systems.
On the structure and control of commands
Authors: Stephenson C. J.
Published: October 2004

An interactive command language, with its underlying data, defines a command environment. In general a command environment supports a number of commands which once issued perform non-interactively, and which when finished leave the old command environment in control. It also supports some special commands which move to other command environments, after which commands are interpreted according to a different set of rules.

The usefulness of a command environment can be extended by programming it, i.e. by dynamically constructing and conditionally executing sequences of its commands; but, unlike a programming language, a command language does not usually contain any general-purpose variables or means for conditional execution. These facilities can however be provided by a command control language, which makes it possible to construct sequences or commands to be issued to the currently active command environment from a program.

A command control language is described, and the usefulness, limitations and repercussions of command language programming are discussed.
The UNIX time-sharing system
Authors: Ritchie Dennis M. , Thompson Ken
Published: October 2004

UNIX is a general-purpose, multi-user, interactive operating system for the Digital Equipment Corporation PDP-1 1/40 and 11/45 computers. It offers a number of features seldom found even in larger operating systems, including

1. A hierarchical file system incorporating demountable volumes,

2. Compatible file, device, and inter-process I/O,

3. The ability to initiate asynchronous processes,

4. System command language selectable on a per-user basis,

5. Over 100 subsystems including a dozen languages.

This paper discusses the usage and implementation of the file system and of the user command interface.
ARGOS
Authors: Day Paul , Hines John
Published: October 2004

“ARGOS” (ARGonne Operating System), which runs on a Xerox Sigma 5 hardware configuration, provides a dynamic multiprogrammed environment which supports the following: data acquisition and interactive control for numerous (currently 19) independently running on-line laboratory experiments; three interactive graphics terminals; FORTRAN IV-H executing at each of 23 remote time-shared terminals; a jobstream from open-shop batch processing; long-term low priority computations (100 CPU hours). The system guarantees the protection of each user's interests by the utilization of the hardware memory-protection feature, internal clocks and disallowing the execution of privileged instructions by user programs. The system is interrupt-driven, with each task running to completion, contingent on its priority. System resources are provided on a first come first served basis, except that rotating memory is queued by request position. System CALLs provide users full access to hardware capability, thus providing user-directed file formats and insuring a minimum of system overhead. However, at some sacrifice in overhead, the user can make use of FORTRAN record-blocking. Core memory, disk space and magnetic tape usage, are assigned dynamically. Parametrization of the system is such that terminal characteristics are specified (one parameter card/terminal) at boot-in time (once/week after preventive maintenance).
Multiprocessor self diagnosis, surgery, and recovery in air terminal traffic control
Authors: Walther W.
Published: October 2004

The rapid growth of global aviation for business and pleasure has created the need for automated terminal systems of increasing complexity and capability. Continued increases in the aircraft population will require higher levels of automation. Sperry Univac is responding to this challenge with a multiprocessing system, including hardware and software, currently under development which will enable controllers to safely manage the crowded skies.
Dynamic storage partitioning
Authors: Denning Peter J. , Spirn Jeffrey R.
Published: October 2004

A model of paged multiprogramming computer systems using variable storage partitioning is considered. A variable storage partitioning policy is one which allocates storage among the active tasks according to a sequence of fixed partitions of main storage. The basic result obtained is, mean processing efficiency is increased and mean fault-rate decreased under a variable partition, provided that the curves of efficiency and fault-rate as a function of allocated space are concave up.
On reference string generation processes
Authors: Arvind  , Kain R. Y. , Sadeh E.
Published: October 2004

Efficient memory management is important for optimizing computer usage. Intuition, simulation, experience, and analysis have contributed to the design of space management algorithms. Analytical models require accurate and concise descriptions of the system's environment. The referencing pattern, describing the sequence of memory addresses, is the environment for memory management problems. One referencing model assigns probabilities to positions in an LRU stack of memory pages. “Local” behavior is easily described using this model. However, the distinctly different behavior among instruction and data references is lost. In this paper we generalize the LRU stack model to an arbitrary number of memory spaces which are selected by the transitions of a Markov chain. The additional detail affects the behavior of the models for a working set management strategy.
A task-scheduling algorithm for a multiprogramming computer system
Authors: Krause K. L. , Shen V. Y. , Schwetman H. D.
Published: October 2004

This paper presents a description and analysis of a task scheduling algorithm which is applicable to third generation computer systems. The analysis is carried out using a model of a computer system having several identical task processors and a fixed amount of memory. The algorithm schedules tasks having different processor-time and memory requirements. The goal of the algorithm is to produce a task schedule which is near optimal in terms of the time required to process all of the tasks. An upper bound on the length of this schedule is the result of deterministic analysis of the algorithm. Computer simulations demonstrate the applicability of the algorithm in actual systems, even when some of the basic assumptions are violated.
The case for capability based computers (Extended Abstract)
Authors: Fabry R. S.
Published: October 2004

The idea of a capability which acts like a ticket authorizing the use of some resource was developed by Dennis and Van Horn as a generalization of addressing and protection schemes such as the code- words of the Rice computer, the descriptors of the Burroughs machines, and the segment and page tables in computers such as the GE-645 and IBM 360/67. Dennis and Van Horn generalized the earlier schemes by extending them to include not just memory, but all systems resources: memory, processes, input/output devices, and so on; and by stressing the explicit manipulation of access control by nonsystem programs. The idea is that a capability is a special kind of address for an object, that these addresses can be created only by the supervisor, and that in order to use any object, one must address it via one of these addresses. The name comes from the fact that having one of these special kinds of addresses for a resource provides one with the capability to use the resource.

The use of capabilities as a protection mechanism has been the subject of considerable interest and is now fairly well understood. Access control schemes using capabilities and capability -like notions are, as a whole, the most flexible and general schemes available. It will in fact be assumed that the reader is familiar with the advantages of capabilities for protection put-poses; a somewhat different advantage of capabilities will be developed here.
Formal requirements for virtualizable third generation architectures
Authors: Popek Gerald J. , Goldberg Robert P.
Published: October 2004

Virtual machine systems have been implemented on a limited number of third generation computer systems, for example CP-67 on the IBM 360/67. The value of virtual machine techniques to ease the development of operating systems, to aid in program transferability, and to allow the concurrent running of disparate operating systems, test and diagnostic programs has been well recognized. However, from previous empirical studies, it is known that many third generation computer systems, e.g. the DEC PDP-10, cannot support a virtual machine system.

In this paper, the hardware architectural requirements for virtual machine systems are discussed. First, a fairly specific definition of a virtual machine is presented which includes the aspects of efficiency, isolation, and identical behavior. A model of third generation-like computer systems is then developed. The model includes a processor with supervisor and user modes, memory that has a simple protection mechanism, and a trap facility. In this context, instruction behavior is then carefully characterized.
Limitations of Dijkstra's Semaphore Primitives and Petri nets
Authors: Kosaraju S. Rao
Published: October 2004

Recently various attempts have been made to study the limitations of Dijkstra's Semaphore Primitives for the synchronization problem of cooperating sequential processes [3,4,6,8]. Patil [8] proves that the semaphores with the P and V primitives are not sufficiently powerful. He suggests a generalization of the P primitive. We prove that certain synchronization problems cannot be realized with the above generalization and even with arrays of semaphores. We also show that even the general Petri nets will not be able to handle some synchronization problems, contradicting a conjecture of Patil (P.28 [7]).
An assessment model for requirements identification in component-based software development
Authors: Jain Hemant , Vitharana Padmal , Zahedi Fatemah "Mariam"
Published: October 2004

Software development literature is replete with studies that demonstrate how ineffective requirements analysis (RA) has led to failed applications. Some of the difficulties encountered in RA however are due to inherent limitations in traditional approach to software development. On the other hand, component-based software development (CBSD) presents a unique approach to developing software. Components advertise the services they offer and could be organized in a knowledge-base (i.e., repository). CBSD paradigm provides an effective communication vehicle for users and analysts by enabling them to uncover requirements as they navigate through the component knowledge-base.In this paper, we draw from the information processing theory (IPT) on problem solving to develop an assessment model for evaluating the impact of CBSD on requirements identification, arguing that the access to components in a knowledge-base facilitates the requirements identification. The key elements of the IPT on problem solving are information processing system of the problem solver, task environment and internal representation of the problem space. We propose that access to a component knowledge-base enhances information processing system of the problem solver and simplifies the task environment which together improve user's internal representation of the problem space. This theoretical framework makes it possible to empirically test the impact of CBSD on requirements identification process.
Career satisfaction for managerial and technical anchored IS personnel in later career stages
Authors: Hsu Maxwell K. , Chen H. G. , Jiang James J. , Klein Gary
Published: October 2004

Information system (IS) personnel have exhibit high incidence of technical and managerial anchors. It has been proposed that IS personnel with technical anchors have difficultly moving into a more advanced career stage that requires a greater emphasis on managerial skills (e.g., leadership) and activities. Using the data from a survey of IS professionals, we find that career satisfaction is positively and significantly correlated with career stage. Moreover, managerially anchored IS professionals are found to be more satisfied in the mentor stage than those who are technically anchored. However, no clear relationship between career anchors and career satisfaction was found in the sponsor stage. It appears that the combined effects of career anchor and stage is a more complex relation than previously thought in the literature. The results indicate that career programs discussed in the literature may need to be adjusted to accommodate advancement for those with a technical career anchor.