bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementing analysable hard real-time sporadic tasks in Ada 9X
Authors: Burns A. , Wellings A. J.
Published: October 2004

In this paper we illustrate how systems containing hard real-time sporadic tasks can be analysed for their worst case behaviour. In order to undertake this schedulability analysis, it is necessary to define the minimum inter-arrival time and/or maximum arrival frequency of sporadic tasks. Furthermore, at run-time it is essential to ensure that sporadic tasks are not invoked more often than has been guaranteed by the analysis. We assume that sporadics are invoked by interrupts and that interrupts can be masked under software control.Sporadic tasks are often analysed using the notion of bandwidth preserving sporadic servers within the Rate Monotonic Scheduling Analysis scheme. At run-time this requires the underlying kernel to support complex execution time monitoring mechanisms. Unfortunately such mechanisms are not generally supported by Ada 9X. This paper shows that by using Deadline Monotonic Scheduling Analysis there is no need to resort to bandwidth preserving sporadic servers, and the facilities available in Ada 9X can be used.
Information systems '95 curriculum model
Authors: Gorgone John T. , Couger J. Daniel , Feinstein David , Kasper George , Longenecker Herbert E.
Published: October 2004

This paper provides a progress report of the joint curriculum task force effort to develop a new model curriculum for undergraduate programs in Information Systems. The curriculum work is the first collaborative effort between ACM and other professional societies associated with information systems education. The paper presents a brief background description, current task force activities, list of recommended courses and course description, and other addressed curricula related issues.
Development of the Domain Name System
Authors: Mockapetris Paul V. , Dunlap Kevin J.
Published: October 2004

The Domain Name System (DNS) provides name service for the DARPA Internet. It is one of the largest name services in operation today, serves a highly diverse community of hosts, users, and networks, and uses a unique combination of hierarchies, caching, and datagram access.This paper examines the ideas behind the initial design of the DNS in 1983, discusses the evolution of these ideas into the current implementations and usages, notes conspicuous surprises, successes and shortcomings, and attempts to predict its future evolution.
A brief overview of ATM
Authors: Siu Kai-Yeung , Jain Raj
Published: October 2004

Asnychronous Transfer Mode (ATM) has emerged as the most promising technology in supporting future broadband multimedia communication services. To accelerate the deployment of ATM technology, the ATM Forum, which is a consortium of service providers and equipment vendors in the communication industries, has been created to develop implementation and specification agreements. In this article, we present a brief overview on ATM protocol layers and current progress on LAN Emulation and Traffic Management in the ATM Forum.
Information technology innovations
Authors: Prescott Mary B. , Conger Sue A.
Published: October 2004

Research based on diffusion of innovation (DOI) theory investigates the evaluation, adoption, and implementation of innovations. Gaining understanding is difficult when tracing results on a study-by-study basis. To remove some of the barriers to comparison of results, we distinguish between innovations according to their locus of impact (IS unit, intra- or inter-organizational) and between studies according to research approach (factor or stage).A representative sample of 70 information technology (IT) related DOI research studies published by IT researchers over the last decade is evaluated using this classification scheme. From the analysis, it appears that the classification scheme may be used to provide a clearer understanding of IT innovation diffusion.Traditional DOI theory appears to be most applicable to ITs which have an intra-organizational locus of impact. ITs with an information system (IS) unit locus of impact appear to require less organizational support, and their extent of implementation appears to be related to nontraditional innovation characteristics such as functionality and efficiency. Inter-organizational locus of impact IT innovations, however, appear to be more affected by contextual and environmental variables, and their differences may be better explained by economic influence or critical mass theories.
Load balancing and fault tolerance in workstation clusters migrating groups of communicating processes
Authors: Petri S. , Langendörfer H.
Published: October 2004

In the past, several process migration facilities for distributed systems have been developed. Due to the complex nature of the subject, all those facilities have limitations that make them usable for only limited classes of applications and environments. We discuss some of the usual limitations and possible solutions. Specifically, we focus on migration of groups of collaborating processes between Unix systems without kernel modifications, and from this we derive the design for a migration system. First experiences with our implementation show that we reach performance figures for the migration that are close to those of real distributed operating system.
Undetectable on-line password guessing attacks
Authors: Ding Yun , Horster Patrick
Published: October 2004

Several 3-party-based authentication protocols have been proposed, which are resistant to off-line password guessing attacks. We show that they are not resistant to a new type of attack called "undetectable on-line password guessing attack". The authentication server is not able to notice this kind of attack from the clients' (attacker's) requests, because they don't include enough information about the clients (or attacker). Either freshness or authenticity of these requests is not guaranteed. Thus the authentication server responses and leaks verifiable information for an attacker to verify his guess.
Raising NP lower bounds to parallel NP lower bounds
Authors: Hemaspaandra Edith , Hemaspaandra Lane A. , Rothe Jörg
Published: October 2004

This issue's column surveys recent progress in raising NP-hardness lower bounds to parallel NP lower bounds. Complexity theorists will learn that Lewis Carroll (unbeknownst to himself) was a fellow complexity theorist. So that readers specializing in algorithms don't feel left out, let me mention that they are in even better company. Algorithms for apportioning the US House of Representatives were designed and debated by Adam, Hamilton, Jefferson, Webster, and other famous figures from American history, as recounted in a page-turner by Balinski and Young ([BY82]; see also [BY85] for a shorter take and [HRSZ96] for a more explicitly computational spin). Looking forward, the next issue's column will be a survey, by Mitsunori Ogihara, of DNA-based computing.
Microcomputer playfulness
Authors: Yager Susan E. , Kappelman Leon A. , Maples Glenn A. , Prybutok Victor R.
Published: October 2004

Previous playfulness research has investigated playfulness as both state and trait phenomena. For example, Webster et al. (1993) examined flow, the state of playfulness in a specific human-computer interaction, while Martocchio and Webster (1992) used a trait-based approach, considering playfulness a characteristic of individuals. This research extends the investigation of playfulness as an individual trait by using a longitudinal study to examine its temporal and situational stability.The Computer Playfulness Scale (Webster & Martocchio, 1992) was administered four times over the course of a five-week summer session to students enrolled in a computer-literacy course, once at the beginning of the class and then following completion of three milestones in the course work. The playfulness instrument was assessed for internal consistency, unidimensionality, and temporal and situational stability. The evidence indicates that the measurement is reliable. The primary question of trait stability (stable versus dynamic) was examined in several ways, supporting the conclusion that playfulness is a stable trait. The implications of these findings and suggested further research are discussed.
How to design dynamic programming algorithms sans recursion
Authors: Pruhs Kirk
Published: October 2004

We describe a method, which we call the Pruning Method, for designing dynamic programming algorithms that does not require the algorithm designer to be comfortable with recursion.
Fast and scalable layer four switching
Authors: Srinivasan V. , Varghese G. , Suri S. , Waldvogel M.
Published: October 2004

In Layer Four switching, the route and resources allocated to a packet are determined by the destination address as well as other header fields of the packet such as source address, TCP and UDP port numbers. Layer Four switching unifies firewall processing, RSVP style resource reservation filters, QoS Routing, and normal unicast and multicast forwarding into a single framework. In this framework, the forwarding database of a router consists of a potentially large number of filters on key header fields. A given packet header can match multiple filters, so each filter is given a cost, and the packet is forwarded using the
least cost matching filter
.In this paper, we describe two new algorithms for solving the least cost matching filter problem at high speeds. Our first algorithm is based on a grid-of-tries construction and works optimally for processing filters consisting of two prefix fields (such as destination-source filters) using linear space. Our second algorithm, cross-producting, provides fast lookup times for arbitrary filters but potentially requires large storage. We describe a combination scheme that combines the advantages of both schemes. The combination scheme can be optimized to handle pure destination prefix filters in 4 memory accesses, destination-source filters in 8 memory accesses worst case, and all other filters in 11 memory accesses in the typical case.
Providing guaranteed services without per flow management
Authors: Stoica Ion , Zhang Hui
Published: October 2004

Existing approaches for providing guaranteed services require routers to manage per flow states and perform per flow operations [9, 21]. Such astatefulnetwork architecture is less scalable and robust thanstatelessnetwork architectures like the original IP and the recently proposed Diffserv [3]. However, services provided with currentstatelesssolutions, Diffserv included, have lower flexibility, utilization, and/or assurance level as compared to the services that can be provided with per flow mechanisms.In this paper, we propose techniques that do not require per flow management (either control or data planes) at core routers, but can implement guaranteed services with levels of flexibility, utilization, and assurance similar to those that can be provided with per flow mechanisms. In this way we can simultaneously achieve high quality of service, high scalability and robustness. The key technique we use is called Dynamic Packet State (DPS), which provides a lightweight and robust mechanism for routers to coordinate actions and implement distributed algorithms. We present an implementation of the proposed algorithms that has minimum incompatibility with IPv4.
Notes on building a relational database management system in Ada
Authors: Poutanen Olavi , Varanki Kari-Matti , Välimäki Tapio
Published: October 2004

It seems, at the moment, that although there have been papers published that deal with database management in an Ada environment there is still very little practical experience in that field.Using Ada we have developed an Ada compatible relational database management system, called DMS/MPS10. In this paper we discuss some of its basic implementation ideas as well as some Ada specific issues that have arisen in the course of the work. Mostly we concentrate on describing how database design and documentation can take place using Ada concepts. That is, defining database domains as Ada types, defining table rows as Ada records etc. At the end of this paper there are some notes on the DMS/MPS10 runtime arrangements.
Programming large and flexible systems in Ada
Authors: Roubine O.
Published: October 2004

The parallel processing facilities of Ada are based on the concept of rendezvous, which introduces a tight coupling between two cooperating tasks. Because of the asynnetry of the rendezvous, and of the typing system, these facilities cannot be used directly in a certain number of cases with particularly severe constraints on the system in terms of size, flexibility or extensibility. We indicate some typical such constraints, and investigate possible solutions in Ada. The performance of such solutions is analyzed, leading to an improved solution, which is then shown to be applicable to a large variety of situations.
Lessons from practical experience teaching hands-on, real-time, embedded system programming with Ada
Authors: Buhr R. J. A.
Published: October 2004

This paper analyzes practical experience at Carleton University with a course in hands-on, real time, embedded system programming with Ada, derives lessons from this experience relatig to the concerns of the Ada community about teaching/learning Ada in this area, and makes consequential recommendations regarding course content, student preparation and resource requirements.
On network-aware clustering of Web clients
Authors: Krishnamurthy Balachander , Wang Jia
Published: October 2004

Being able to identify the groups of clients that are responsible for a significant portion of a Web site's requests can be helpful to both the Web site and the clients. In a Web application, it is beneficial to move content closer to groups of clients that are responsible for large subsets of requests to an origin server. We introduce
clusters
---a grouping of clients that are close together topologically and likely to be under common administrative control. We identify clusters using a ``network-aware" method, based on information available from BGP routing table snapshots.
User-level process checkpoint and restore for migration
Authors: Bozyigit M. , Wasiq M.
Published: October 2004

In simple words, process checkpointing means saving the state of a process, so that, it can be reconstructed in the future. Checkpointing followed by restore is important for the purpose of load balancing and fault tolerance. For load balancing, processes may have to be migrated among workstations. Before migrating, a process has to be checkpointed, so that, it can be restored from where it left off. For fault tolerance, a process must be ready for a restore at a different site. Thus, an earlier checkpoint must be ready for the restore. In both cases the process needs to be restarted from its latest checkpoint, thus work done preceding the checkpoint is not wasted. This paper discusses simple techniques of implementing a user-level checkpoint and restore operations for Unix processes. The technique does not require any changes in the user programs or the operating system. The details given show the simplicity of the implementation.
Load-tolerant differentiation with active queue management
Authors: Bodin U. , Schelen O. , Pink S.
Published: October 2004

Current work in the IETF aims at providing service differentiation on the Internet. One proposal is to provide loss differentiation by assigning levels of drop procedence to IP packets. In this paper, we evaluate the active queue management (AQM) mechanisms RED In and Out (RIO) and Weighted RED (WRED) in providing levels of drop precedence under different loads. For low drop precedence traffic, FIO and WRED can be configured to offer sheltering (i.e., low drop precedence traffic is protected from losses caused by higher drop precedence traffic). However, if traffic control fails or is inaccurate, such configurations can cause starvation of traffic at high drop precedence levels. Configuring WRED to instead offer relative differentiation can eliminate the risk of starvation. However, WRED cannot, without reconfiguration, both offer sheltering when low drop precedence traffic is properly controlled and avoid starvation at overload of low drop precedence traffic. To achieve this, we propose a new AQM mechanism, WRED with Thresholds (WRT). The benefit of WRT is that, without reconfiguration, it offers sheltering when low drop precedence traffic is properly controlled and relative differentiation otherwise. We present simulations showing that WRT has these properties.
How to compute fast a function and all its derivatives
Authors: Morgenstern Jacques
Published: October 2004

This note is about a simple and algorithmic proof of the striking result of BAUR-STRASSEN [1] showing that the complexity of the evaluation of a rational function of several variables and all its derivatives is bounded above by three times the complexity of the evaluation of the function itself.
Computational geometry
Authors: Mitchell Joseph S. B. , O'Rourke Joseph
Published: October 2004

A compendium of thirty previously published open problems in computational geometry is presented
On the origin of power laws in Internet topologies
Authors: Medina Alberto , Matta Ibrahim , Byers John
Published: October 2004

Recent empirical studies [6] have shown that Internet topologies exhibit power laws of the form
y
=
x
α
for the following relationships: (P1) outdegree of node (domain or router) versus rank; (P2) number of nodes versus outdegree; (P3) number of node pairs within a neighborhood versus neighborhood size (in hops); and (P4) eigenvalues of the adjacency matrix versus rank. However, causes for the appearance of such power laws have not been convincingly given. In this paper, we examine four factors in the formation of Internet topologies. These factors are (F1) preferential connectivity of a new node to existing nodes; (F2) incremental growth of the network; (F3) distribution of nodes in space; and (F4) locality of edge connections. In synthetically generated network topologies, we study the relevance of each factor in causing the aforementioned power laws as well as other properties, namely diameter, average path length and clustering coefficient. Different kinds of network topologies are generated: (T1) topologies generated using our parametrized generator, we call BRITE; (T2) random topologies generated using the well-known Waxman model [12]; (T3) Transit-Stub topologies generated using GT-ITM tool [3]; and (T4) regular grid topologies. We observe that some generated topologies may not obey power laws P1 and P2. Thus, the existence of these power laws can be used to validate the accuracy of a given tool in generating representative Internet topologies. Power laws P3 and P4 were observed in nearly all considered topologies,
but
different topologies showed different values of the power exponent α. Thus, while the presence of power laws P3 and P4 do not give strong evidence for the representativeness of a generated topology, the value of α in P3 and P4 can be used as a litmus test for the representativeness of a generated topology. We also find that factors F1 and F2 are the key contributors in our study which provide the resemblance of our generated topologies to that of the Internet.
Role-based access control and the access control matrix
Authors: Saunders G. , Hitchens M. , Varadharajan V.
Published: October 2004

The Access Matrix is a useful model for understanding the behaviour and properties of access control systems. While the matrix is rarely implemented, access control in real systems is usually based on access control mechanisms, such as access control lists or capabilities, that have clear relationships with the matrix model. In recent times a great deal of interest has been shown in Role Based Access Control (RBAC) models. However, the relationship between RBAC models and the Access Matrix is not clear. In this paper we present a model of RBAC based on the Access Matrix which makes the relationships between the two explicit. In the process of constructing this model, some fundamental similarities between certain capability models and RBAC are revealed.
File system encryption with integrated user management
Authors: Ludwig Stefan , Kalfa Winfried
Published: October 2004

Existing cryptographic file systems for Unix do not take into account that sensitive data must often be shared with other users, but still kept secret. By design, the only one who has access to the secret data is the person who encrypted it and therefore knows the encryption key or password. This paper presents a kernel driver for a new encrypted file system, called Fairly Secure File System (FSFS), which provides mechanisms for user management and access control for encrypted files. The driver has been specifically designed with multi user systems in mind. FSFS also tries to prevent unintentional transfer of sensitive data to unencrypted file systems, where it would be stored in plaintext.
Multicast Video-on-Demand services
Authors: Ma Huadong , Shin Kang G.
Published: October 2004

The server's storage I/O and network I/O bandwidths are the main bottleneck of VoD service. Multicast offers an efficient means of distributing a video program to multiple clients, thus greatly improving the VoD performance. However, there are many problems to overcome before development of multicast VoD systems. This paper critically evaluates and discusses the recent progress in developing multicast VoD systems. We first present the concept and architecture of multicast VoD, and then introduce the techniques used in multicast VoD systems. We also analyze and evaluate problems related to multicast VoD service. Finally, we present open issues on multicast VoD as possible future research directions.
An implementation supporting distributed execution of partitioned ada programs
Authors: Jha R. , Eisenhauer G. , Kamrad J. M. , Cornhill D.
Published: October 2004

This paper describes the implementation of a novel paradigm for building distributed application software in Ada. The entire application is written as a single program, which is partitioned for distributed execution
after
its design. The partitioning is expressed in a separate notation called the Ada Program Partitioning Language (APPL). A modified compilation system accepts an Ada program and an APPL specification for it as input, to produce a separate executable image for each node. There is considerable freedom in what Ada entities may be placed on different nodes. The two-phase design approach helps reduce design complexity, and allows experimentation with different strategies for allocating software to hardware without requiring software redesign. Our implementation is currently under the final stages of testing using a modified version of the Ada compiler validation test-suite.Section 1 presents an overview of our paradigm and the rationale behind it. Section 2 introduces APPL. Section 3 describes our current implementation. Section 4 discusses the question of what Ada entities should be distributable, and compares several alternatives. Finally, section 5 concludes the paper with pointers to future work.
Naming Ada tasks at run-time
Authors: Cheng J. , Ushijma K.
Published: October 2004

This paper proposes a new strategy for uniquely naming Ada tasks at run-time. The strategy has two features. First, it can easily be used to name tasks in their activations. Second, it does not impose a total order with respect to the start of activations and/or executions on the tasks to be named.
Controlling deadlock in Ada
Authors: Levine Gertrude
Published: October 2004

Ada's concurrency constructs provide synchronization and mutual exclusion mechanisms to control resource allocation. These constructs, if improperly used, can cause indefinite or infinite postponement of completion of service.Hembold and Luckham [3] and Cheng, Araki, and Ushijima [2] identify classes of these anomalies in order to aid in their detection. In this article we continue their discussion of the classification and control of these unbounded delays.
The evolution of information centers: a stage hypothesis
Authors: Magal Simha R.
Published: October 2004

Information centers (IC) have undergone numerous changes since they were first created to facilitate and control end-use computing. Today, ICs have evolved to play a significant role in an organization's computing activities. As such, the function and management of ICs are of major concern to information systems (IS) executives. The evolving nature of the IC, however, constrains these IS executives in their decisions regarding the role and future directions for ICs. This study proposed a stage hypothesis for information center evolution. Key benchmark variables were identified and the behavior of these variables over time were used to arrive at the stage hypotheses. A survey of IC managers was conducted to evaluate the accuracy of the proposed hypothesis and is to determine the current status of ICs in organizations. The results provided strong support for the hypothesis. Knowledge of how key benchmark variables behave during the evolution of ICs is invaluable to IS executives in their efforts to provide direction for ICs in their organizations.
A loop-detect packet based self stabilizing bridge protocol for extended-LANs
Authors: Bielkowicz P. , Parr G.
Published: October 2004

It has become the trend for network managers to require redundant bridges as back-up for bridge/link failures. The inherent problem with such a scheme is that it causes certain packets to loop continuously around the topology causing severe degradation to the performance of the overall system. Various solutions to the problem of combating this phenomenon exist, most notably the Spanning Tree Algorithm (STA) by Perlman [2]. Solutions based on a loop detect packet have been proposed previously [1]. but were never given enough thought to make it a viable alternative to work based on the STA. It is hoped to show a more powerful loop detect packet based algorithm in this paper. The problems which have plagued the previous loop detect approach [1] will be seen to be dealt with, and further extensions proposed. This algorithm is for multiple port local/remote bridges.
Rationalizing key design decisions in the ATM user plane
Authors: Grossman Daniel B.
Published: October 2004

Any technology requires some number of key design decisions. In the case of the ATM user plane, the choices to use fixed length, 53 byte cells and virtual connections were unorthodox from the perspective of many in the networking research community. This paper attempts a technical justification for those design decisions.
OverQoS
Authors: Subramanian Lakshminarayanan , Stoica Ion , Balakrishnan Hari , Katz Randy H.
Published: October 2004

This paper proposes
OverQoS
, an architecture for providing Internet QoS using overlay networks. OverQoS empowers third-party providers to offer enhanced network services to their customers using the notion of a
controlled loss virtual link
(CLVL). The CLVL abstraction bounds the loss-rate experienced by the overlay traffic; OverQoS uses it to provide differential rate allocations, statistical bandwidth and loss assurances, and enables explicit-rate congestion control algorithms.
XORP
Authors: Handley Mark , Hodson Orion , Kohler Eddie
Published: October 2004

Network researchers face a significant problem when deploying software in routers, either for experimentation or for pilot deployment. Router platforms are generally not open systems, in either the open-source or the open-API sense. In this paper we discuss the problems this poses, and present an eXtensible Open Router Platform (XORP) that we are developing to address these issues. Key goals are extensibility, performance and robustness. We show that different parts of a router need to prioritize these differently, and examine techniques by which we can satisfy these often conflicting goals. We aim for XORP to be both a research tool and a stable deployment platform, thus easing the transition of new ideas from the lab to the real world.
Efficient topology-aware overlay network
Authors: Waldvogel Marcel , Rinaldi Roberto
Published: October 2004

Peer-to-peer (P2P) networking has become a household word in the past few years, being marketed as a work-around for server scalability problems and "wonder drug" to achieve resilience. Current widely-used P2P networks rely on central directory servers or massive message flooding, clearly not scalable solutions. Distributed Hash Tables (DHT) are expected to eliminate flooding and central servers, but can require many long-haul message deliveries. We introduce Mithos, an content-addressable overlay network that only uses minimal routing information and is directly suitable as an underlay network for P2P systems, both using traditional and DHT addressing. Unlike other schemes, it also efficiently provides locality-aware connectivity, thereby ensuring that a message reaches its destination with minimal overhead. Mithos provides for highly efficient forwarding, making it suitable for use in high-throughput applications. Paired with its ability to have addresses directly mapped into a subspace of the IPv6 address space, it provides a potential candidate for native deployment. Additionally, Mithos can be used to support third-party triangulation to quickly select a close-by replica of data or services.
EINSTEIN
Authors: Fogel Marc , Winograd Joseph
Published: October 2004

EINSTEIN is an internal driver developed to evaluate the performance of a mixed-mode time sharing, batch operating system. It allows a single experimenter at a terminal to place an arbitrary, reproducible, interactive load on the system. Such a facility has numerous uses: system debugging and testing, benchmarking successive releases of a system, estimating system saturation points for different configurations, evaluating alternate processor and memory scheduling algorithms, etc. A task is defined either by specifying the values for a parameterized model of task behavior or by specifying the actual terminal input for the task, called the script. The parameterized model and the script-driven tasks are discussed in detail. An actual experience in which both types of EINSTEIN tasks were used to help isolate a reported performance degradation is related.
Migration / evolution of security towards wireless ATM
Authors: Patiyoot D
Published: October 2004

This proposal aims to outline possibilities for the migration, evolution path from second-generation systems (GSM) to wireless ATM regarding security aspect.Some of the factors and parameters of security affecting the migration path towards wireless ATM are identified. Also expected, planned security features for wireless ATM is explained and compared to second generation cellular systems.This work is done following the work of ASPeCT ( Advanced Security for Personal Communications Technologies) in a similar manner.
A QoS service for IP video applications on demand over DTM
Authors: Barenco Cláudia J. , Saloña Arturo Azcorra , Moreno José Ignacio
Published: October 2004

The Differentiated Services model (DiffServ) provides a great flexibility in defining a variety of services through PHBs (
Per Hop Behaviors
) and traffic conditioners. It fits in well with the Integrated Services model (IntServ), jointly offering features such as: QoS signaling; admission control; channel management; assignment of resources (buffer and bandwidth); sorter configuration; and establishment of traffic agreements. With this integration you can have a scalable, flexible, and dynamic QoS environment in networks of the Internet core.This article describes and analyzes the DGF (
DTM Guaranteed Forwarding
) service that guarantees a minimum rate of retransmission of packets, based on RSVP signaling and traffic agreements (SLA), as well as losses close to the error rate of the physical medium, which are ideal features for video applications on demand.When this service is provided, the aforementioned QoS models are integrated with the transport and switching solution called DTM (
Dynamic Synchronous Transfer Mode
), a fast circuit switching technology. DTM is simple, cost-effective, provides QoS features, and is naturally dynamic in supplying bandwidth as well as flexible in fitting in with other IETF QoS models.Thus in the proposed architecture, IPoDQoS (
IP over DTM QoS
), we make use of the dynamism of network protocols and we offer managed VBR traffic in the IP layer (i.e.: DGF service) not originally offered in DTM technology.
An open approach for deploying programming nodes into communication networks
Authors: Rocha Cris Amon C. , Braga Aécio Paiva , de Souza José Neuman
Published: October 2004

Nowadays, we are facing in the computer network research community new challenges related to the concepts of programmable and active networks. Great efforts have been spent to make current data communication networks more flexible and dynamic. Unfortunately, such efforts are followed by complexity and, therefore, the process of deploying the mechanisms has been committed. In order to make this process simpler, this work presents an open approach for having programmable nodes that make computer networks more dynamic in terms of adding new services without increasing complexity. This approach presents SNPI (Simple Network Programming Interface), which is a group of skeletons and data structures resources that make possible to the programmers and developers a fast deployment of new services into the network. The mechanism presented allows the access to internal mechanisms of data flow processing in the network nodes.
Survey of design goals for operating systems
Authors: Abernathy David H. , Mancino John S. , Pearson Charls R. , Swiger Dona C.
Published: October 2004

The paper reports the results of a literature search on the subject "design goals for operaring systems." In addition, design goals of specific operating systems are reviewed and a general set of operating system design goals is developed. Special-purpose design goals and conflicts among design goals are also discussed.
An operating system based on the concept of a supervisory computer
Authors: Gaines R. Stockton
Published: October 2004

An operating system which is organized as a small supervisor and a set of independent processes are described. The supervisor handles I/O with external devices - the file and directory system - schedules active processes and manages memory, handles errors, and provides a small set of primitive functions which it will execute for a process. A process is able to specify a request for a complicated action on the part of the supervisor (usually a wait on the occurrence of a compound event in the system) by combining these primitives into a "supervisory computer program." The part of the supervisor which executes these programs may be viewed as a software implemented "supervisory computer." The paper develops these concepts in detail, outlines the remainder of the supervisor, and discusses some of the advantages of this approach.
Synchronization of communicating processes
Authors: Habermann A. Nico
Published: October 2004

Formalization of a well-defined synchronization mechanism can be used to prove that concurrently running processes of a system communicate correctly. This is demonstrated for a system consisting of many sending processes which deposit messages in a buffer and many receiving processes which remove messages from that buffer. The formal description makes it very easy to prove that the buffer will neither overflow nor underflow, that senders and receivers will never operate on the same message frame in the buffer nor will they run into a deadlock.
Process synchronization without long-term interlock
Authors: Easton William B.
Published: October 2004

A technique is presented for replacing long-term interlocking of shared data by the possible repetition of unprivileged code in case a version number (associated with the shared data) has been changed by another process. Four principles of operating system architecture (which have desirable effects on the intrinsic reliability of a system) are presented; implementation of a system adhering to these principles requires that long-term lockout be avoided.
An approach to distributed software systems
Authors: Bacon Jean
Published: October 2004

A conceptual framework is given for software designed as an integrated whole for a distributed system or local area network. The ISO reference model for open systems interconnection is incorporated into the design approach. A summary of mechanisms provided in systems and languages for inter-process communication is given and each mechanism is evaluated in the context of support for distributed software. A classification of typical inter-process interactions is given as a further basis for comparison.
On the generalized critical region construct
Authors: Kant Krishna , Silberschatz Abraham
Published: October 2004

In his paper "Implementation of a Generalized Critical Region Construct", Ford has proposed a modification to Brinch Hansen and Hoare's concept of Conditional Critical Regions. In this paper, we point out some of the problems with the original proposal and present many improvements in order to make the construct more useful.
A progress report on the Desperanto research project
Authors: Mamrak Sandra A. , Leinbaugh Dennis , Berk Toby S.
Published: October 2004

The Desperanto research project has been investigating topics in the area of distributed computing systems since the Fall of 1980. The project addresses problems that arise in the design and implementation of software support for general-purpose resource sharing in networks consisting of heterogeneous nodes. Thus it is most closely related to the prototype RSEXEC system [19], the National Software Works project [2], Rochester's Intelligent Gateway [8] and the Livermore Network Communications system [21]. It is influenced less directly by other contemporary systems which address distributed computing and operating system issues in different contexts such as special-purpose distributed applications, homogeneous architectures or shared memory environments [1] [3] [4] [6] [7] [16] [17] [18] [23].Some results have been published to date [9] [10] [11] [12], and other results are currently in the review process [13]. Although it is still premature to publish the details of the solutions to the design problems in journal (or archival) form, this report has been prepared to describe design issues and progress made to date. This is intended as an informal status report for a wide readership.
National parallel processing research council executive committee charter
Authors: Sopka John R.
Published: October 2004

The fundamental objective of the National PARALLEL PROCESSING RESEARCH COUNCIL is to foster cooperation among industry, university, and government bodies in support of research and development on parallel computing systems. Such cooperation is considered essential to expand more rapidly both the understanding of hardware and software concepts and their utilization in development of actual computing systems.This proposal attempts to specifically identify the responsibilities and activities of an Executive Committee for the National PARALLEL PROCESSING RESEARCH COUNCIL.
A proposal for an architectural approach which apparently solves all known software-based internal computer security problems
Authors: Routh Richard LeRoy
Published: October 2004

Computer security violations have become a serious threat to both corporate and national defense activities. By extending the work done by Myers et. el. in the development of the capability based addressing system for the SWARD at IBM, a Computer architectural approach has been developed which solves all known software based internal computer security problems. The problems solved include (but are not restricted to):(1) Violations of priority and access priveleges by highly skilled users,(2) The clasic "Trojan Horse" problem,(3) Access and alteration of sensitive data-bases by unauthorized users(4) The "Lost Key" problem of advanced capability based addressing systems.This solution proposes and develops an architectural approach which manages a sophisticated capability based addressing system entirely in hardware. As a result, the architectures developed by this approach tend to be somewhat hardware intensive in that they require unusual amounts of control and memory not available to any user (it is maintained soley for security purposes).
The covert channel limiter revisited
Authors: Loepere Keith
Published: October 2004

In a previous article
1
, I introduced the idea of a mechanism (the covert channel limiter) that would watch for the potential uses of covert channels and affect the responsible process (or process group) only when such potential uses exceeded the allowable bandwidth for covert channels. Recent work involving the design of the Opus operating system (target class B3) has refined and extended this idea. This paper extends the informal basis for the covert channel limiter and extends its possible utility.
Active block layout
Authors: Guangchun Luo , Jun Zhang , Xianliang Lu , Jun Lu
Published: October 2004

In traditional computer infrastructure, almost all the files that can be randomly accessed are stored on the disk. This paper presents a new Active Block Layout (ABL) mechanism. Basing on this mechanism, the friequently accessed data blocks are automatically copied and optimizedly distributed on the disk. By improving the access speed of these data blocks, we can enhance the performance of the storage system. Meanwhile, this paper presents the concept of the disk potential bandwidth. Using this concept, we could copy and synchronize the data efficiently without degrading the disk's response time significantly. In this paper, we introduce the disk scheduling, the disk potential bandwidth and heat-release mechanism. The experiment results of ABL are also provided. The experiments prove that the ABL mechanism can greatly shorten the access delay of the disk files and improve the performance of the file system.
PAPER
Authors: Pascal Patricia , Monteil Thierry
Published: October 2004

This paper presents an approach to study the influence of deterministic customers in queueing system. This is used to make real time decision to manage resources. This method is applied to the scheduler of multiprocessor machines with round robin model. The transient probabilities which take care of the deterministic events are given. They are used to express a relation for the variation of the expectation of the number of processes. This relation is simplified with a general method called fluid approximation and used to predict the execution time of the deterministic events.
The Hamiltonian circuit problem and automaton theory
Authors: Litow B.
Published: October 2004

We exhibit an elegant automaton-theoretic construction that yields a 2O(n)-time algorithm to count the number of Hamiltonian circuits in a graph withnvertices.
Distributed message passing operating systems
Authors: Chandras Rajan G.
Published: October 2004

Distributed computing (variably - and confusedly - called parallel computing or concurrent computing) has reduced the quantum of discretization of computing power. No longer do computers cleanly can into the clearly demarkated categories of Microcomputer, Minicomputer, Mainframe and Supercomputer. By the simple expedient of putting together a variable number of processors (of variable size/power), we now have computers falling almost continuously throughout the range from micros to supercomputers. New terms have been coined for intermediate ranges, like SuperMinis and MiniSupers. Distributed computing is gradually being accepted as the dominant high-performance computing paradigm of the future. Once again, however, hardware seems to have left software behind. While it is fairly straightforward to build a distributed computer, developing efficient software for it appears to be a different ballgame altogether. Software technology for centralized operating systems is stable and reliable, but tight coupling (shared memory) puts an inherent limit on the degree of parallelism, and hence on the performance of parallel computers. It is, thus, very important to establish a firm understanding of the concept of distributed computing and distributed operating systems (DOS).Distributed operating systems (where "distributed" implies distribution of functionality and control) are generally said to be of two types: DOS/RPC (Remote Procedure Call) and DOS/MP (Message Passing). While variants of these two abound, no strong third alternative is seen today. For the loosely-coupled architecture, RPC at a greater depth reduces to message passing. It is thus of fundamental importance to fully explore and exploit the paradigm of message passing. This article attempts to give a brief but encompassing overview of distributed message passing operating systems.
Developing an activity-based costing approach for system development and implementation
Authors: Ooi Ginny , Soh Christina
Published: October 2004

This paper proposes the use of the Activity Based Costing (ABC) approach to software estimation. Like other more traditional approaches to software estimation, ABC provides man-day estimates. In addition, it also provides detailed costing information that is useful for management control and decision making. The paper shows how the ABC approach can be applied to software estimation by building an ABC model using data from twenty-two projects in a financial services firm. The model is then used for estimation, and comparisons between estimated and actual man-day are computed (variance analysis). The data generated by the model and from the variance analysis are useful for management control and decision making in areas such as resource allocation, outsourcing of specific development activities, and learning from adoption of new development tools and practices.
Modeling data for the summary database
Authors: Orli Richard J.
Published: October 2004

Summarization abstracts information and so reduces flexibility. The challenge of summary database design is providing adequately flexible information to meet the needs of the business process it serves. This article addresses this challenge by examining the basic forms of summarization as a set of model record forms, each with advantages and disadvantages. The function of information implied by these forms is described in terms of the business process model. This model is the basis of a proposed data scheme that organizes information "top-down" into the core of a flexible, effective, summary database design.
ACM SIGACT news distributed computing column 13
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 describes the PODC 20th anniversary Special Issue published by
Distributed Computing
journal.
A brief history of NTP time
Authors: Mills David L.
Published: October 2004

This paper traces the origins and evolution of the Network Time Protocol (NTP) over two decades of continuous operation. The technology has been continuously improved from hundreds of milliseconds in the rowdy Internet of the early 1980s to tens of nanoseconds in the Internet of the new century. It includes a blend of history lessons, technology milestones and series of experiments that shape, define and record the early history of the Internet and NTP.This narrative is decidedly personal, since the job description for an Internet timekeeper is highly individualized and invites very few applicants. There is no attempt here to present a comprehensive tutorial, only a almanac of personal observations, eclectic minutiae and fireside chat. Many souls have contributed to the technology, some of which are individually acknowledged in this paper, the rest too numerous left to write their own memoirs.