bluuebunny/crossref_metadata_2025 huggingface dataset:
Internet vulnerabilities related to TCP/IP and T/TCP
Authors: de Vivo Marco , de Vivo Gabriela O. , Koeneke Roberto , Isern Germinal
Published: October 2004

The Internet put the rest of the world at the reach of our computers. In the same way it also made our computers reachable by the rest of the world. Good news and bad news! Over the last decade, the Internet has been subject to widespread security attacks. Besides the classical terms, new ones had to be found in order to designate a large collection of threats:
Worms, break-ins, hackers, crackers, hijacking, phrackers, spoofing, man-in-the-middle, password-sniffing, denial-of-service
, and so on.Since the Internet was born of academic efforts to share information, it never strove for high security measures. In fact in some of its components, security was consciously traded for easiness in sharing. Although the advent of
electronic commerce
has pushed for "real security" in the Internet, there are still a large number of users (including computer scientists) that are very vulnerable to attacks, mostly because they are not aware of the nature (and ease) of the attacks and still believe that a "good" password is all they need to be concerned about.Aiming for a better understanding of the subject, we wrote a first paper
[1]
in which we discussed several threats and attacks related to
TCP/IP
. The present work is an extension of the first one, and its main goal is to include
T/TCP
in the discussion. Additionally, in an effort to make this paper more comprehensive, we included some sections from the former.Besides the description of each attack (the
what
), we also discuss the way they are carried out (the
how
) and, when possible, the related means of prevention, detection and/or defense.
Collection of network information in active networks
Authors: Li Yuhong , Wolf Lars
Published: October 2004

Collection of information about the state of the network is very important for applications both in active networks and in traditional passive networks. However, the existing methods for the collection and prediction of network state cannot meet the needs of complex and intelligent applications. Active networks provide an environment that supports the injection and execution of application-specified codes in the network nodes, and consequently suggest possibilities for the solving of such a problem. In this article we present a new method for the collection of network state information by describing how active network techniques can be used to collect this information more freely and in a user-specific way. We give also an implementation of this approach to collect network resource information and evaluate it by measurements. By using this method, users can specify both the content and the format of the network resource information that they want to acquire as well as nodes at which they want to gather these information.
HIP
Authors: Dovrolis Constantinos , Thayer Brad , Ramanathan Parameswaran
Published: October 2004

The standard way to notify the processor of a network event, such as the arrival or transmission of a packet, is through interrupts. Interrupts are more effective than polling, in terms of the per packet send/receive latency. Interrupts, however, incur a high overhead both during and after the interrupt handling, because modern superscalar processors use long pipelines, out-of-order and speculative execution, and multi-level memory systems, all of which tend to increase the interrupt overhead in terms of clock cycles. In this paper, we attempt to reduce the network interface overhead by introducing a hybrid scheme (HIP) that uses interrupts under low network load conditions and polling otherwise. Even though such hybrid schemes have been proposed in the past, the polling period in HIP is adjusted dynamically based on the rate of the arriving packet stream. In this way, the increase in the per packet latency, which occurs with polling, is quite low. This is quantified with trace-driven simulations, which also show that the per packet overhead with HIP is significantly reduced compared to the conventional interrupt-based mechanism. HIP would be beneficial for high bandwidth network interfacing in servers with a heavy WWW or streaming media workload.
The design, implementation and initial evaluation of an advanced knowledge-based process scheduler
Authors: Suranauwarat Sukanya , Taniguchi Hideo
Published: October 2004

Traditional operating systems control the execution of programs regardless of how often they are run. This raises the question: can't the often run or the often used programs provide better performance if an operating system had an ability to optimize their execution behavior based on a knowledge the operating system had obtained from their previous execution(s)? In this paper, we integrate this ability into a part of an operating system called a process scheduler and examine its cost and benefit. Our initial evaluations show that the cost involved in our scheduler is small and the processing time can be reduced by using this scheduler.
A high resolution disk I/O trace system
Authors: Huang Tao , Xu Teng , Lu Xianliang
Published: October 2004

Disk access patterns are more important to understand as the gap between processor and disk performance is increasing. Obtaining disk I/O traces from real system is the first step to analyze disk access patterns, and tracing disk I/O is the first step to obtain disk I/O traces from real system. This paper implements a high resolution disk I/O trace system built into Linux, without adding noticeable processor load to the system. Each trace record contains the following content about a single physical I/O to a specified disk: timings (including start and completion time) to 1 µ s resolution, disk number and partition, start address, transfer size, flags for read/write, and the type of block accessed.
On the techniques of enhancing the security of block ciphers
Authors: Dawu Gu , Yi Wang
Published: October 2004

A new triple encryption scheme and a secure cryptographic mode, named NTE and NPCBC repectively, are presented, which are followed by the discussion of the security of NTE and NPCBC.
Comments on "tagged semaphores"
Authors: Trono John A.
Published: October 2004

Modifications are made to a proposed solution for a specialized synchronization problem. These changes remove inconsistent semaphore usage and preclude the possibility of deadlock that is present in the proposed solution.
Mobile agent security based on payment
Authors: Sonntag Michael , Hörmanseder Rudolf
Published: October 2004

Mobile agents are autonomous entities that handle tasks for their owner. Agents act on their own by reacting to changes and by planning their course of action. These agents can move from one server to another. In the future, agents will also be supplied with real money in some form to pay for resources or services.In this paper we discuss a dynamic security architecture, in which permissions are assigned in exchange for information (money). The decision as to which permissions are available, as well as how much they cost, is based on the source of the code, the owner/user of the code and what other information the agent is willing (or able) to provide.We discuss the advantages and limitations of assessing permissions in monetary terms, rather than binary granting or denial of permissions according to pre-set classes. A test-framework has been implemented using Java.
The distributed ASCI Supercomputer project
Authors: Bal Henri , Bhoedjang Raoul , Hofman Rutger , Jacobs Ceriel , Kielmann Thilo , Maassen Jason , van Nieuwpoort Rob , Romein John , Renambot Luc , Rühl Tim , Veldema Ronald , Verstoep Kees , Baggio Aline , Ballintijn Gerco , Kuz Ihor , Pierre Guillaume , van Steen Maarten , Tanenbaum Andy , Doornbos Gerben , Germans Desmond , Spoelder Hans , Baerends Evert-Jan , van Gisbergen Stan , Afsermanesh Hamideh , van Albada Dick , Belloum Adam , Dubbeldam David , Hendrikse Zeger , Hertzberger Bob , Hoekstra Alfons , Iskra Kamil , Kandhai Drona , Koelma Dennis , van der Linden Frank , Overeinder Benno , Sloot Peter , Spinnato Piero , Epema Dick , van Gemund Arjan , Jonker Pieter , Radulescu Andrei , van Reeuwijk Cees , Sips Henk , Knijnenburg Peter , Lew Michael , Sluiter Floris , Wolters Lex , Blom Hans , de Laat Cees , van der Steen Aad
Published: October 2004

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project.
Further comments on "A Correct and Unrestrictive Implementation of General Semaphores"
Authors: Trono John A. , Taylor William E.
Published: October 2004

Over a decade ago, a race condition was discovered in a specific implementation of the counting semaphore operations P and V. Several corrections to that implementation were published. These were subsequently critiqued and eventually the discussion ended. This article will expose a newly discovered race condition in one of the corrections.
The implementation of dynamite
Authors: Iskra K. A. , van der Linden F. , Hendrikse Z. W. , Overeinder B. J. , van Albada G. D. , Sloot P. M. A.
Published: October 2004

Parallel programming on clusters of workstations is increasingly attractive, but dynamic load balancing is needed to make efficient use of the available resources. Dynamite provides dynamic load balancing for PVM applications running under Linux and Solaris. It supports migration of individual tasks between nodes in a manner transparent both to the application programmer and to the user, implemented entirely in user space. Dynamically linked executables are supported, as are tasks with open files and with direct PVM connections. In this paper, we describe the technical aspects of migrating message-passing tasks.
Making serial number based authentication robust against loss of state
Authors: Mitchell Chris J.
Published: October 2004

In this paper a novel method for making serial number based authentication protocols resilient against database failure is described. The method is applicable to the situation where a single server wishes to authenticate itself to a number of clients, but cannot reliably maintain a sequence number database. The solution has recently been included in a draft international standard for third generation mobile telecommunications, [1].
A distributed token-based algorithm for the dynamic resource allocation problem
Authors: Bouabdallah A. , Laforest C.
Published: October 2004

This paper presents a distributed algorithm for the general dynamic resource allocation problem. A process may request any subset of the system resources (that may be available in several instances) during a request session. We focus on the message complexity which measures the number of messages a process incurs when it requests resources. The proposed algorithm is tokens-based and uses between 0 and
n
+ 3
k
messages, where
k
is the total number of resources and
n
the total number of processes. On average,
O
(log
n
) messages are used if
k
is constant. Our solution allows several processes to enter their critical section simultaneously with respect to the exclusive access to resources requirement.
Internet security attacks at the basic levels
Authors: de Vivo Marco , de Vivo Gabriela O. , Isern Germinal
Published: October 2004

The Internet put the rest of the world at the reach of our computers. In the same way it also made our computers reachable by the rest of the world. Good news and bad news!. Over the last decade, the Internet has been subject to widespread security attacks. Besides the classical terms, new ones had to be found in order to designate a large collection of threats:
Worms, break-ins, hackers, crackers, hijacking, phrackers, spoofing, man-in-the-middle, password-sniffing, denial-of-service,
and so on.Since the Internet was born of academic efforts to share information, it never strove for high security measures. In fact in some of its components, security was consciously traded for easiness in sharing. Although the advent of
electronic commerce
has pushed for "real security" in the Internet, there is yet a huge amount of users (including scientists) very vulnerable to attacks, mostly because they are not aware of the nature (and ease) of the attacks and still believe that a "good" password is all they need to be concerned about.We wrote this paper aiming for a better understanding of the subject. In the paper we report some of the major actual known attacks. Besides the description of each attack (the
what
), we also discuss the way they are carried on (the
how
) and, when possible, the related means of prevention, detection and/or defense.
Planning for the market?
Authors: Robinson Bruce , Wilson Francis
Published: October 2004

Enterprise Resource Planning is the most overarching attempt so far to control a firm's economic environment using information technology. An analysis of its functions, potential, and limitations thus requires an economic model that provides a conceptual framework for understanding the enterprise's goals, activities and environment. Marx's analysis of the processes of accumulation and circulation of capital is used here to assess ERP systems, with the conclusion that, rather than being a fad, ERPs attempt to answer certain general problems of capital accumulation that are particularly acute today. Their limitations are shown to be inherent in the capital form itself, in particular the dependence of capital on market relations in exchange.
What's an MIS paper worth?
Authors: Gill T. Grandon
Published: October 2004

The article performs an economic analysis of MIS salary data and survey data from a variety of sources in order to estimate the marginal value of a published MIS refereed journal article to its author, a faculty member. The three main conclusions it reaches are:• A published MIS refereed journal article can be worth approximately $20,000 in incremental pay, over an assumed five-year lifetime, to a faculty member. That value is derived from two sources: (1) the ability such a paper gives the author to move to higher-paying institutions, and (2) the incremental impact of the paper on an individual's compensation across institutions having the same teaching load.• What constitutes a valid "article" is institution-dependent, so the faculty member must ensure that the publication outlets targeted for such an article are consistent with the institution's objectives and quality criteria.• In order to realize the actual marginal value of a publication computed in this paper, a faculty member must be willing to relocate, perhaps on a reasonably regular basis, to ensure that he or she does not fall victim to the salary inversion phenomenon that is currently widespread within the MIS academic community.The paper does not attempt to quantify the impact of a publication on a number of other potential contributors to its author's income, including the long-term possibility of becoming an eminent scholar and the possibility that publications will lead to outside income opportunities. As a consequence, it is quite possible that the actual value of an article may exceed the paper's estimate for some individuals.
A stage maturity model for enterprise resource planning systems use
Authors: Holland Christopher P. , Light Ben
Published: October 2004

Enterprise Resource Planning (ERP) systems dominate the information technology landscape of many companies. Organizations are at different stages in the implementation process ranging from the initial analysis of implementation options, through completed standard implementations and to the sophisticated exploitation of ERP systems using advanced knowledge management, customer relationship management and supply chain management systems. The authors present a maturity model for ERP systems that identifies three stages and this is illustrated using case data selected from the study which is based on 24 organizations in the US and Europe. In Stage 1, organizations are managing legacy systems and starting the ERP project. In Stage 2, implementation is complete and the functionality of the ERP system is being exploited across the organization. In Stage 3, organizations have normalised the ERP system into the organization and are engaged in the process of obtaining strategic value from the system by using additional systems such as customer relationship management, knowledge management and supply chain planning. It is shown that the organizations follow an S-shaped curve, and that most companies are in the middle stage. An analysis of the implications for organizations at each stage of the maturity model is presented which will be of value to practising managers. The implications are categorised as impacts on cost, entropy, complexity, flexibility and strategic competitiveness.
A systemic framework for the field of information systems
Authors: Bacon C. James , Fitzgerald Brian
Published: October 2004

The main aim of this paper is to present a systemic framework of what the field of Information Systems (IS) is about; its connecting areas and its central theme. It was born out of a search for structure in providing a cohesive picture of the subject and field of IS for students and business managers. The average manager and executive has difficulty in obtaining an integrated and holistic view of information systems, and it is said that this leads to a lack of alignment between IS and the strategic aims of the enterprise. Students, particularly MBA students, have a similar problem. Using a large number of disparate data sources, including a delphic survey of leading academics, the paper adopted a grounded theory approach in developing an integrating framework of five main areas for the field: (1) IS development, acquisition & support (2) people & organization, (3) information & communications technology, (4) operations & network management, and (5) information for knowledge work, customer satisfaction & business performance. The latter area is proposed as the central, distinguishing theme for the field. The paper also discusses the implications of the framework and how it might be used in teaching, the organizational setting, and IS research.
Using an adapted grounded theory approach for inductive theory building about virtual team development
Authors: Sarker Suprateek , Lau Francis , Sahay Sundeep
Published: October 2004

This paper outlines how the grounded theory methodology was adapted to develop a process model of collaboration in virtual teams. The data analysis was conducted using an adapted version of open coding, axial coding, and selective coding procedures offered by Strauss and Corbin (1990). In applying the grounded theory procedures, the objective was to stay true to the goals and spirit of each coding procedure, while modifying details of procedural steps that were too mechanistic or impractical. The paper develops a meta-theoretical framework through a synthesis of the data, the symbolic interactionist perspective, and structuration theory. This framework is an alternative to the "paradigm model" during selective coding of data.
The evaluation of IT ethical scenarios using a multidimensional scale
Authors: Ellis T. Selwyn , Griffith David
Published: October 2004

Concerns about the increased use and abuse of information technology have evolved into more formalized evaluations of computer ethics in many organizations. While ethical situations regarding computer usage, privacy, and ownership have been previously researched by focusing on ethics as a holistic construct, recent ethics research has produced an ethics scale which measures not one but three dimensions of ethics: moral equity, relativism, and contractualism. The purpose of this research is to extend previous research in which computer users evaluated ethics using a single item. The authors utilize a multidimensional scale that identifies the ethical rule or principle that was violated. They then compare the unidimensional scale to the multidimensional scale and discuss the tradeoffs involved in adding scale items.
Acquiring conceptual data modeling skills
Authors: Ryan Sherry D. , Bordoloi Bijoy , Harrison David A.
Published: October 2004

Conceptual data modeling has been defined as a complex task for designers. This study draws from educational and psychological research in examining the training of novices in conceptual data modeling. Specifically, an experiment was conducted to determine the effects of self-efficacy and cooperative, team-based participation on complex data modeling skills. Subjects in the cooperative learning treatment did not perform significantly better on a conceptual data modeling task than those assigned to an individual-work treatment. This calls into question the value of using the cooperative learning approach for short-duration IS training. However, the data also showed that self-efficacy was significantly and positively related to skill acquisition. Self-efficacy, then, is an important consideration for improving achievement when teaching complex information systems development skills to IS novices.
Facilitating localized exploitation and enterprise-wide integration in the use of IT infrastructures
Authors: Kayworth Timothy R. , Sambamurthy V.
Published: October 2004

Two often-contradictory dilemmas confront firms in their efforts at promoting IT-based innovation: facilitate localized exploitation of the IT infrastructure within individual business units, but also ensure enterprise-wide integration of IT innovation initiatives to facilitate business applications that exploit inter-unit synergies. Therefore, developing an IT infrastructure that is conducive to both localized exploitation and enterprise-wide integration is important. In this context, IT infrastructure standards are an important element of the IT infrastructures that shape managers' perceptions about the responsiveness of their infrastructures to their firms' IT innovation needs.This study examines the role of PC/LAN infrastructure standards in facilitating attention to localized exploitation and enterprise-wide integration. It identifies three attributes of PC/LAN infrastructure standards: comprehensiveness, flexibility, and level of enforcement. Through rich case studies in four bureaucratic organizations, the study develops insights about how PC/LAN infrastructure standards influence perceptions about the responsiveness of the PC/LAN infrastructures for localized exploitation and enterprise-wide integration. The emergent findings point to the influence not only of the standards, but also of the organizational context within which these standards are evolved, implemented, and used. The study offers valuable insights for both IS practitioners and researchers about the use of PC/LAN infrastructure standards in organizations.
The ten commandments of data warehousing
Authors: Sammon David , Finnegan Pat
Published: October 2004

Data warehousing can offer great potential for organizations. Nevertheless, implementing a data warehouse is a complex project that has caused difficulty for organizations. This paper presents the results of a study of four mature users of data warehousing technology. Collectively, these organizations have experienced many problems and solutions in relation to implementing data warehousing. These experience are captured in the form of ten organizational prerequisites for implementing data warehousing. The authors believe that this model could potentially be used by organizations to internally assess the likelihood of data warehousing project success, and to identify the areas that require attention prior to commencing implementation.
An investigation of the roles of individual differences and user interface on database usability
Authors: Curl Steven S. , Olfman Lorne , Satzinger John W.
Published: October 2004

This research seeks to understand to what extent leveraging the graphical user interface's ability to convey spatial information can improve a user's ability to write effective database queries. This capability is believed to be especially important when nontechnical individuals, with diverse backgrounds and cognitive abilities, are expected to interact directly with these systems in the query formulation process.This study makes use of recent developments in graphical user interface technology to manipulate the level of spatial visualization support provided by the interface. A laboratory experiment was conducted to explore the influence of interface style and the spatial visualization ability of the user on the performance of the query development process. The application used in the experiment was a visual database query system developed for this study. One hundred sixty-two volunteers participated in the experiment. Spatial visualization ability was assessed using a paper-folding test. The results indicate that both spatial visualization support of the system and spatial visualization ability of the user are important components of database usability.
SIGACT news complexity theory column 35
Authors: Hemaspaandra Lane A.
Published: October 2004

I was surprised and delighted at a recent conference when the complexity class Θ
2

p

suddenly popped up in a talk (by Markus Holzer on work by him and Pierre McKenzie) where it is was not exactly something one would have before-hand expected to come into play. After hearing the rest of Markus's remarkable talk (which he illustrated using toys from his daughter), I was much hoping that the authors would be so kind as to write a guest column; they very generously agreed to, and that column appears below.So, what is Θ
2

p

? Θ
2

p

is the class of languages acceptable via parallel access to NP, and has many equivalent alternate definitions and characterizations (see [KSW87, Hem89, Wag90]), such as the one used in the paper below. This class was first studied by Papadimitriou and and Zachos in 1983 [PZ83] (though in a form that at that time was not known to be equivalent to the definition just mentioned), and has played an important role in complexity theory, e.g., Kadin [Kad89] proved that the polynomial-time hierarchy collapses to Θ
2

p

if NP has sparse Turing-complete sets. Recently, the class has turned out to play other surprising roles, such as in analyzing the complexity of electoral systems (see the survey [HH00]) and in understanding the performance of greedy algorithms [HR98, HRS01]. In fact, a survey column a few years ago was devoted to overviewing such raised-to-Θ
2

p

lower bounds [HHR97].
Bill Gasarch and SIGACT News need YOU!
That is, the next issue will contain a guest column edited by Bill Gasarch, which will collection opinions on the future of the P-versus-NP question. Bill very much wants a broad range of opinions, and will be setting up a web page (http://www.cs.umd.edu/~gasarch/pnp/) describing how you can get your opinions to him. He may even put up a series of polling questions there, so please go there, vote early, and vote often!And in the issues following that will be articles by M. Schaeffer and C. Umans on complete sets at and beyond the polynomial hierarchy's second level, by A. Nickelsen and T. Tantau on partial information classes, and by R. Paturi on the complexity of
k
-SAT.
ACM SIGACT news Distributed Computing Column 6
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
two parts:

a survey of DISC'01 by Panagiota Fatourou, and

a survey of Self-Stabilization at WSS'01 and DISC'01 by Ted
Herman.

Many thanks to Gioula and Ted for contributing to this issue.
The computational complexity of the local postage stamp problem
Authors: Shallit Jeffrey
Published: October 2004

The well-studied local postage stamp problem (LPSP) is the
following: given a positive integer
k,
a set of positive
integers 1 =

a
1
< a
2
< … <
a
k

and an integer h ≥ 1, what is the smallest
positive integer which cannot be represented as a linear
combination
Σ

1≤i≤k
x
1
a
i

where Σ

1≤i≤k
x
1
≤ h

and
each

x
i

is a non-negative integer? In this note
we prove that LPSP is NP-hard under Turing reductions, but can be
solved in polynomial time if
k
is fixed.
A language for systems not just software
Authors: Amey Peter
Published: October 2004

The
specification
and
implementation
of software-intensive systems have generally been viewed as separate processes with differing notations. There are good reasons for trying to use notations capable of bridging the gap between the two. The
spark
language was originally concerned solely with providing an unambiguous subset of Ada that was suitable for rigorous static analysis and formal verification. Evolution of
spark
's system of formal comments or
annotations
has resulted in a language which now provides parallel descriptions of required system behaviour and software implementation. Analyses performed by the
spark
Examiner bind these parallel descriptions together. The result, not foreseen by the original designers of
spark
, is a language that can be used to describe systems rather than just implement software.
Automating software module testing for FAA certification
Authors: Santhanam Usha
Published: October 2004

Structural testing, also called code-based or white-box testing, is performed for the purpose of exercising the code thoroughly. The code coverage measurements are used to evaluate the effectiveness of the test cases toward this goal. Manual, code-based testing is cumbersome and time-consuming. Automation provides help in selecting test data, applying those test cases to the software, and deciding whether a program has been tested enough by providing coverage metrics. This paper describes an automated module testing process for software written in Ada using a tool set called Test Set Editor (TSE). TSE consists of a proprietary set of programs which work in combination with Microsoft Excel spreadsheet program and home grown test scripts written in Tcl/tk. Use of the tool set is shown to yield significant cost savings in constructing structural tests needed to satisfy FAA certification requirements for safety-critical software.
Reengineering an Ada95-programmed command and control information system by using UML
Authors: Faβbender Heinz
Published: October 2004

We describe the concepts and experiences we have made in an ongoing project by modeling and reengineering an experimental command and control information system which is nearly completely implemented in Ada95. For this purpose, we use the UML tool
Software through Pictures
from Aonix which includes a reengineering component that produces class diagrams from the source code. These diagrams serve as a starting point of a model of the complete system which itself serves as a base for modeling the most important requirements of the system. Furthermore, by refining the model through state-transition diagrams and redesigning the system the UML tool allows an automatic code generation for components which will be implemented in an other language like Java. Hence, the result of the reengineering process should be a more structured system, where proprietary solutions are replaced by commercial products (e.g. an application server) as much as possible.
Teaching computer science with robotics using Ada/Mindstorms 2.0
Authors: Fagin Barry S. , Merkle Laurence D. , Eggers Thomas W.
Published: October 2004

We present one approach to teaching basic computer science concepts with robotics, using an Ada interface to Lego Mindstorms
™
. We show simple problems put to students with no programming experience, discuss the solutions, and for each concept explain the advantages of using robots to teach it.
An object-oriented metrics suite for Ada 95
Authors: Pritchett William W.
Published: October 2004

Ada 95 added object-oriented programming capabilities to the existing Ada standard. The object-oriented paradigm results in new relationships within and among software modules. Traditional software product metrics, i.e., those metrics developed for functionally oriented software, do not account for these new relationships and may be insufficient for use in object-oriented development. This paper addresses this deficiency by 1) defining a set of object-oriented metrics tailored to Ada 95 software, and 2) providing empirical evidence of their validity. This set of metrics includes product measures quantifying the class-related software attributes of size, coupling, cohesion, and complexity. The results indicate that many of the metrics examined do correlate to the number of revisions made to the classes during development.
Concurrent programming for the control of hexapod walking
Authors: Thirion Bernard , Thiry Laurent
Published: October 2004

Ada95 is a powerful language with a great number of original constructions. Learning these constructions requires the finalization of projects that are both interesting and motivating for students, as well as the coverage of the different constructions during the project. Moreover, the field of mobile robotics is one that requires real-time programming and appropriate software architectures. More particularly, legged robots offer a real challenge as regards autonomy and the coordination of movements of the different legs. This field proves fruitful for the definition of projects on concurrent programming. The present paper describes such a project about an architecture for an omnidirectional legged robot. In a resolutely object-oriented approach, the project helps to teach the main constructions of the Ada language. Among others, it deals with child units, generics, tagged types and type extension, tasking, protected objects, family entries, asynchronous transfer of control, discriminants, etc. Numerous extensions can be considered within this project.
A checkpoint-based high availability run-time system for Windows NT clusters
Authors: Youhui Zhang , Dongsheng Wang
Published: October 2004

This paper presents a high availability run-time system----ChaRM-NT, a Checkpoint-based Rollback recovery system for parallel applications on a cluster of computers (COCs) based on Windows NT. ChaRM-NT implements an insert-mode, reduced coordinated checkpointing and rollback recovery (CRR) mechanism. Owing to the above techniques, ChaRM-NT can recover parallel applications from the checkpointing file upon system failures. In addition we have implemented a new coordinated checkpointing algorithm that only requires O(n) control messages where n is the number of participating processes. Independent on message passing environments (MPEs) ChaRM-NT implements a portable single process CRR library. Therefore it is very easy to adapt to different MPEs and it supports PVM and MPI for NT now.
A multi-protocol cross-domain communication model for metacomputing systems
Authors: Peng Bi , Fei Xie , Guangwen Yang , Dingxing Wang
Published: October 2004

Metacomputing system is a kind of heterogeneous and dynamic distributed computing system in WAN (Wide Area Network). Communication model of metasystems must tackle the heterogeneous and dynamic problems, and has the ability to pass messages in WAN. After analyzing characteristics and deficiencies in common methods, this paper proposes a new communication model for metasystems. This model is based on Java, whose platform independence and data serialization hide the heterogeneity of various nodes in WAN; its multi-protocol mechanism-association of TCP protocol and UDP protocol-enhances its stability and efficiency. The model has two communication modes: direct mode and proxy mode, used in different conditions. Together, they can span different administrative domains and implement a communication environment transparent to users in WAN. Moreover, some other mechanisms, such as communication management and receiving buffer improve its transfer efficiency.
Efficient flooding with Passive Clustering (PC) in ad hoc networks
Authors: Kwon Taek Jin , Gerla Mario
Published: October 2004

An ad hoc network is a fast deployable self-configuring wireless network characterized by node mobility, dynamic topology structure, unreliable media and limited power supply. Nodes in an ad hoc network must cooperate and carry out a distributed routing protocol in order to make multi-hop communications possible. On Demand Routing is one of the most popular routing styles in ad hoc networks. In On Demand Routing, "flooding" is used to find a feasible route from source to destination. The function of flooding is to deliver a packet from one source to every other node in the system. Conventional flooding can be very costly in On Demand networks in terms of network throughput efficiency as well as node energy consumption. The main reason is that the same packet is rebroadcast unnecessarily several times (redundant rebroadcast). Indeed, the penalty of redundant rebroadcast increases when the size of network grows and the density of network increases. In this paper we introduce a novel clustering scheme, call Passive Clustering that can reduce the redundant rebroadcast effect in flooding. We demonstrate the efficiency of the proposed scheme in the AODV (Ad hoc, On demand Distance Vector) routing scheme.
Sensor Network Tomography
Authors: Zhao Jerry , Govindan Ramesh , Estrin Deborah
Published: October 2004

Wireless sensor networks have been attracting increasing research interest given the recent advances in miniaturization and low-cost, low-power design. Consisting of a large collection of small wireless, low-power, unattended sensors and/or actuators, wireless sensor network technology poses its unique design challenges. Given their unattended nature and their complexity, it is critical that the users be given continuously updated indications of the sensor network
health,
i.e., explicit knowledge of the overall state of the sensor network after deployment. We call such indications of network health
scans.
Such macroscopic view of resources or activities in large sensor networks can provide users early warning of system failure, aid in incremental deployment of sensors, or tuning sensor collaboration algorithms.Monitoring wireless sensor networks leads to different challenges compared to existing diagnosis protocols for the Internet, or monitoring systems in other domains such as telecommunication networks, or power generation systems. The monitoring system should introduce minimal impact on network lifetime, scale with network size, yet preserve the
fidelity
of the overall picture. We propose
Sensor Network Tomography
to construct abstracted scans of sensor network health by applying localized algorithms in sensor networks for energy-efficient
in-network aggregation
of local representations of scans. Rather than collect detailed state information from each individual sensor node and then process centrally, this technique builds a composite scan by combining local scans piecewise on their way towards a collecting point. When local scans are aggregated, detailed information at an individual node may be lost. However, the compactness of such an abstracted representation can reduce the communication and processing cost significantly.
DNS performance and the effectiveness of caching
Authors: Jung Jaeyeon , Sit Emil , Balakrishnan Hari , Morris Robert
Published: October 2004

The Domain Name System (DNS) is an essential part of the Internet infrastructure and most Internet applications depend on the correct operation of DNS prior to establishing a connection to a remote host. We seek to understand the client-perceived performance and behavior of DNS and investigate the effectiveness of its caching mechanisms. Our goal is to identify the factors that affect DNS response latency, the errors and failure modes of DNS, and its scalability. An analysis of the effectiveness of DNS caching is especially important in light of several recent changes in the way DNS is used. Content distribution networks (CDNs) and popular Web sites with multiple servers are increasingly using DNS as a level of indirection to help balance load across servers, provide fault tolerance, or to direct each client request to a topologically nearby server.
From the Chair
Authors: Sipior Janice C. , Schatzberg Laurie , Leidner Dorothy , Pendharkar Parag G.
Published: October 2004

Greetings! The vote for the merger of ACM-SIGMIS and ACM-SIGCPR (Special Interest Group on Computer Personnel Research) is upon us. Please look for a postal mailing of the proposal letter detailing the merger and a ballot to be issued by ACM. I strongly recommend you vote in favor of the proposed merger, if you have not already done so.The merger will strengthen SIGMIS. In particular, we will gain an annual conference, which I would like to broaden to include general topics of interest to the MIS community. I would like you to consider attending this year's conference.
MMAIM: a software development method for Ada, part II—Example
Authors: Carter J.
Published: October 2004

Part I of this paper described the notation and method for the Martin Marietta Ada Implementation Method (MMAIM). Part II demonstrates the use of MMAIM with an example. This allows the quality of the solution produced by MMAIM to be evaluated.
An Ada multitasking solution for the sieve of Eratosthenes
Authors: Anderson G.
Published: October 2004

The Sieve of Eratosthenes, an algorithm for calculating prime numbers, has been used for years as a benchmark for evaluating the processing power of single CPUs. A recent modification to the sieve algorithm provides a concurrent solution method for calculating prime numbers. This paper describes an Ada program which uses a multitasking solution for the Sieve of Eratosthenes. The program illustrates the use of Ada tasking to obtain concurrency in the solution of compute-intensive numerical algorithms and may also serve as a benchmark program for evaluating multiple CPU systems.
Mapping Ada onto embedded systems: memory constraints
Authors: Tetewsky A. , Clough A. , Racine R. , Whittredge R.
Published: October 2004

Running Ada programs on a self-targeting system with "virtually" unlimited memory (such as a mainframe), is quite different from running Ada on an embedded target. On self-targeting systems, the compiler and linker will automatically distribute the code, data, constants, and task-stacks onto available resources; the user need not worry about the details. On the other hand, the Ada developer in an embedded environment must understand how to explicitly instruct the development system to allocate resources. For example, to override default settings, (usually set to make the compiler look good on small benchmark programs), 'STORAGE_SIZE length representation settings must be given for task and access types, and linker directives must be given for size and location of code, data, heap, and stack areas. While embedded system technology has always required such settings, many of the parameters could be determined using the programmer's knowledge of implementation details. With Ada, the compiler and linker hide the implementation and the user is faced with setting these parameters with little or no guidance.Unfortunately, few, if any, Ada texts deal with how to set embedded system parameters. In addition, CASE tools usually do not help in these areas. To further complicate matters, even Ada compiler manuals do not adequately describe how to set embedded system parameters solely as a function of Ada constructs. Instead, compiler manuals provide guidelines based not only on Ada constructs but also on other parameters that only run-time system experts understand. Substantial time can be wasted trying to derive the setup values. Incorrect guesses may necessitate recompiling those portions of the program that are affected by representation clause changes.This article will develop formulas that will help estimate the minimum memory and CPU execution needs of an Ada program as a function of source code constructs. The formulas should, 1) help designers and programmers to better assess whether Ada programs will fit in a target environment, 2) reduce recompilation time when representation specifications are present in the specification portion of packages, and 3) remind programmers of the execution costs of various Ada language constructs.
Knowledge based systems and Ada: an overview of the issues
Authors: Collard P. , Goforth A.
Published: October 2004

The goal of this paper is to present an overview of the issues of using Ada in Artificial Intelligence (AI). The purpose of this paper is to act as a catalyst and a focus for these ongoing discussions. Our perspective is one from a cross-cultural vantage point. On one side is the Ada community that represents the engineer's "how to" culture; and, on the other side, the AI community that represents the scientist's "what" and "why" culture. Differences in communication media -
i.e
. programming languages - are the direct result of the different focus of the two cultures. We discuss some of the obstacles to a marriage of the two and assess what are the current promising development paths for overcoming these.
Dynamic bandwidth allocation in a network
Authors: Maly K. , Overstreet C. , Qiu X. , Tang D.
Published: October 2004

Recently protocols have been introduced which enable us to integrate periodic traffic (voice or video) and aperiodic traffic (data) and to extend the size of local area networks without any loss in speed and capacity. One of these, the DRAMA protocol, is based on broadband technology and allows for dynamic allocation of bandwidth to clusters of nodes in the total network. In this paper we propose a distributed algorithm to allocate bandwidth in a
fair
manner, where we have defined fair to mean that every node in the network, regardless of its location, should have the same expected access delay to the net. We show by means of simulation that the algorithm is stable and within a few percentage points of the optimal solution. Stability is measured in terms of the time it takes the system to return to near optimal distribution of the bandwidth after strong disturbances. The algorithm is shown to handle total reallocation of the resources within O(100ms).
Exploiting recursion to simplify RPC communication architectures
Authors: Cheriton D. R.
Published: October 2004

Current communication architectures suffer from a growing collection of protocols in the host operating systems, gateways and applications, resulting in increasing implementation and maintenance cost, unreliability and difficulties with interoperability. The
remote procedure call (RPC)
approach has been used in some distributed systems to contain the diversity of application layer protocols within the procedure call abstraction. However, the same technique cannot be applied to lower layer protocols without violating the strict notion of layers.

In this paper, we show how the RPC approach can be used for lower layer protocols so that the resulting “layer violations” generate a simple recursive structure. The benefits of exploiting recursion in a communication architecture are similar to those realized from its use as a programming technique; the resulting protocol architecture minimizes the complexity and duplication of protocols and mechanism, thereby reducing the cost of implementation and verification. We also sketch a redesigned DoD Internet architecture that illustrates the potential benefits of this approach. This work was sponsored in part by the Defense Advanced Research Projects Agency under contract N00039-84-C-0211, by Digital Equipment Corporation, by the National Science Foundation Grant DCR-83-52048 and by ATT Information Systems.