Change search
Refine search result
1234567 51 - 100 of 454
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Björling, Erik
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Hoff, Anna
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    An Evaluation of a Maintenance Model: A comparison with theory and results from case studies2002Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This master thesis was performed in cooperation with SchlumbergerSema. During the project we identified several maintenance methodologies and studied the characteristics of both the ISO and IEEE standard. The base for our evaluation of the CURE maintenance model (developed by SchlumbergerSema) were both the result of our case study that comprised interviews from five maintenance projects as well as maintenance literature available. Both the interviews and the literature studies resulted in lists of requirements that each area make on a maintenance model. We compare the CURE model to the requirements found within these two areas. Based on the result of the comparison we give our recommendations for maintenance in general, maintenance within SchlumbergerSema as well as specific recommendations for the CURE development team. Our conclusions drawn from our work were mostly positive about CURE. However we have suggested several issues for further development such as e.g. certification to a standard. Other conclusions are that no matter what model you choose as a maintenance model, make sure that you implement the model fully. A major pitfall is to allow it to become "just a fancy book on the shelf".

  • 52.
    Björnsson, Jens
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Analys av pop-ups genererade från adware2003Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    This thesis is about adware, which is very popular today. The adwares are used to, among other things, down- and upload files from other users on the Internet. One thing that most users of such programs are not aware of is that many of the adwares contain spyware. These spywares install themselves simultaneously with the adwares. Two of the spyware features is to generate pop-ups in the web browser and to direct advertisment from the users web habits. In some cases the users can protect themselves against pop-ups by installing additional software. To investigate these problems, five adwares have been exposed to five tests.

  • 53.
    Bladh, Thomas
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    StepTree: A File System Visualizer2002Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    A 3D visualization tool for file system hierarchies is presented. The visualization technique used is based on the Tree-map / nested Venn diagram concept and is capable of visualizing metrics and attributes such as size, change and file type for thousands of nodes simultaneously. Size is visualized through node base area, change is visualized through the ghosting and hiding of unchanged nodes and file type is visualized through colors. Actions such as navigation and selection are performed exclusively in 3D. Finally a method for improving the visibility of nodes through the equalization of sibling nodes is proposed.

  • 54.
    Bladh, Thomas
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Carlsson, Johan
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    XML in the User Interface Context2001Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    The purpose of this thesis is to investigate to what extent XML (Extensible Markup Language) based languages are suitable for use as user interface definition languages in terms of their flexibility. The primary method used is qualitative analysis of scientific papers, literary resources on the target field, practical experiences as well as certain essential non-scientific literature such as standards documents and more practically oriented reference literature as well as on-line resources. XML has been shown to support international characters, the separation of user interface and logic as well as cross platform development very well. The derivative standards utilize these fundamental characteristics of XML in this context and add their own contribution to the mix. Our conclusion is that XML as such is ideally suited for creating flexible user interface definition languages. By flexible we mean that they exhibit some degree of all the flexibility factors reusability, customizability and localizability. The p articular XML based languages we have looked at, namely XUL (XML-based User Interface Language) and UIML (User Interface Markup Language) have also been found to add varying degrees of extra weight to the flexibility factors already found in XML. The findings indicate for example that the levels of abstraction in a particular derived language greatly affect the level of additional flexibility achieved through the use of the language in question.

  • 55.
    Boldt, Martin
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Wieslander, Johan
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Investigating Spyware in Peer-to-Peer Tools2003Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Peer-to-Peer (P2P) tools are used exclusively when their users are connected to the Internet, thus constituting a good foundation for online commercials to help finance further tool development. Although software that displays ads (adware) is very common, activity monitoring or information collecting software that spies on the users (spyware) may be installed together with the P2P tool. This paper will present a method for examining P2P tool installations and present test results from a few of the most common P2P tools. It will also discuss whether these tools, with their bundled software, make any privacy intrusions. Finally, the method itself will be evaluated and suggestions of refinements will be proposed.

  • 56. Boldt, Martin
    et al.
    Wieslander, Johan
    Carlsson, Bengt
    Investigating spyware on the internet2003Conference paper (Refereed)
  • 57.
    Borowski, Jimmy
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Software Architecture Simulation: Performance evaluation during the design phase2004Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Due to the increasing size and complexity of software systems, software architectures have become a crucial part in development projects. A lot of effort has been put into defining formal ways for describing architecture specifications using Architecture Description Languages (ADLs). Since no common ADL today offers tools for evaluating the performance, an attempt to develop such a tool based on an event-based simulation engine has been made. Common ADLs were investigated and the work was based on the fundamentals within the field of software architectures. The tool was evaluated both in terms of correctness in predictions as well as usability to show that it actually is possible to evaluate the performance using high-level architectures as models.

  • 58. Bosch, Jan
    Abstracting object state1997In: OBJECT ORIENTED SYSTEMS, ISSN 0969-9767, p. 1-&Article in journal (Refereed)
    Abstract [en]

    The term `state' has many different meanings, depending on the context in which it is used. In the implementation phase, it refers to the values of the instance variables of the object; during design, it refers to states used in finite state models or their derivatives. For both interpretations, problems have been identified: (1) the way clients of an object access its state is defined in an ad hoc manner, (2) the conventional object-oriented model provides no means to change the interface of an object dynamically on the basis its state or the type of client accessing it, (3) finite state machine approaches are not uniformly integrated in the object-oriented model nor do they provide sufficient complexity reduction for modelling the dynamic behaviour, and (4) no support is provided for defining active states. In this paper we introduce the concept of abstract object state as a solution to these problems. This concept provides a systematic technique to explicitly define an abstraction of the object state which is placed at the interface of the object. The abstract object state consists of static states, but also of active states which can be seen as time derivatives of static states. We show that the abstract object state provides a more uniform approach to object behaviour specification than do finite state models. The concepts discussed have been implemented in the layered object model ((LOM)-O-AY), an extended object-oriented model which is supported by a translator to C++, an execution environment and an integrated development environment.

  • 59. Bosch, Jan
    Evolution and composition of reusable assets in product-line architectures: A case study1999Conference paper (Refereed)
    Abstract [en]

    In this paper, a case study investigating the experiences from evolution and modification of reusable assets in product-line architectures is presented involving two Swedish companies, Axis Communications AB and Securitas Larm AB. Key persons in these organisations have been interviewed and information has been collected from documents and other sources. The study identified problems related to multiple versions of reusable assets, dependencies between assets and the use of assets in new contexts, The problem causes have been identified and analysed, including the early intertwining of functionality, the organizational model, the time to market pressure, the lack of economic models and the lack of encapsulation boundaries and required interfaces.

  • 60. Bosch, Jan
    NOSA'99: Proceedings of the Second Nordic Workshop on Software Architecture1999Report (Other academic)
    Abstract [en]

    Software architecture research is receiving increased amounts of attention in academia as well as in industry. Therefore, in 1997 the initiative was taken by the University of Karlskrona/Ronneby to start a network of academic and industrial partners, SARIS, interested in various aspects of software architecture. The intention of the SARIS (Software Architec-ture Research in Sweden) network is to bring together partners with common interests, exchange experiences through the mailing list and regular meetings and to develop cooperation wherever possible. The term software architecture is somewhat overloaded, but most experts agree that it primarily refers to the top-level decomposition of a system into its main components and the interaction between these components. A second aspect is that software architecture design is primarily concerned with the non-functional requirements (also properties or quality attributes) of software systems, rather than their functionality. Attributes can be categorized into operational attributes, such as efficiency, reliability, robustness and cor-rectness, and development attributes, such as maintainability, flexibility and reusability. The architecture structures the functionality required from a system such that the non-functional requirements are fulfilled.

  • 61. Bosch, Jan
    Software architecture2000Conference paper (Refereed)
  • 62. Bosch, Jan
    Software product lines2000Conference paper (Refereed)
  • 63. Bosch, Jan
    Software Product Lines: Three Examples2000Report (Other academic)
    Abstract [en]

    This report presents the results of a course on software product lines. The assignment in the course was to develop a software product line. . During the course, the students had to develop the following artifacts in groups: product line architecture, component designs, product derivations, modifiability assessment and a prototype. The results of the course are described in this report

  • 64. Bosch, Jan
    Specifying frameworks and design patterns as architectural fragments1998Conference paper (Refereed)
    Abstract [en]

    Object-oriented software architectures, such as design patterns and frameworks, have Sound extensive use in software industry. Their implementation in traditional object-oriented programming languages, however, is often difficult, since no support for the explicit specification of software architectures is provided. In. this paper, we develop the notion of architectural fragments, i.e. reusable architectural specifications that describe a design pattern, or a framework architecture. An architectural fragment describes the structure of an architecture in terms of its components (roles), the architect architecture-specific behaviour of the components and the architecture-specific interaction between the components. Fragments can be composed with each other and with reusable components. To illustrate the use of fragments, we describe the role and architecture language constructs in the layered object model ((LOM)-O-AY) and present examples.

  • 65. Bosch, Jan
    Third Student Conference on Advanced Object-Oriented Concepts1999Report (Other academic)
    Abstract [en]

    The articles in this research report are the result of the efforts of the students of the master course on advanced object-oriented concepts. The course is part of the software engineering master year at the University of Karlskrona/Ronneby. During the course, the students were introduced to about 20 advanced object-oriented concepts, such as delegation, prototype-based languages, reflection, typing, real-time and concurrent object-oriented languages, dynamic binding, garbage collection, delegating compiler objects, design patterns and frameworks. Rather than passively being present at the classes and listening to the lectures, the students were required to themselves present these new concepts. This required considerable amounts of active searching and independent knowledge acquisition from the students that had, subsequently, to be converted in a one to two hour lecture. The lecture was followed by a discussion involving all students. The organisation of the course lead to a very effective learning of the various concepts that were part of the course. Another, very important, aspect of the course was that each student was required to write a research paper on a subject within the object-oriented domain. One requirement on the article was that it had to be problem-oriented in that it had to identify a problem and subsequently propose a solution to the problem. Rather than writing a literature survey, the student was required to write a paper that contained a (possibly minor) scientific contribution to the object-oriented domain. During the course, writers workshops were organised during which students, in groups, read and commented on papers written by their colleagues. The results of this part of the course are gathered in this research report. Fourteen student research papers form the contents of this research report. The articles have been classified into four categories, i.e. reuse and evolution, object-oriented languages, software design and object-oriented frameworks. The reader will recognise, perhaps surprisingly, that many of the papers are strongly founded in practical experiences and address relevant technical problems that our software industry has to deal with on day to day basis. The explanation for this can be found in the project-oriented organisation of the software engineering study program and the strong relation to the local software industry. During the first three years of their studies, the students have experienced the real problems in software engineering and during the master year the students learn to reflect on these problems and to develop solutions. At the end of the course for this year, I am happy that I can conclude that the goals of the course have been more than achieved. Many of the lectures were of very good quality, the participation in the discussions was more than satisfactory and the research papers are very worthwhile reading. The course required from the students, but also from the teacher, a considerable effort, that, almost certainly, resulted in a highly valuable learning experience. For my part, I look with great satisfaction back on the course and hope for many successful repetitions in the future.

  • 66. Bosch, Jan
    et al.
    Lundberg, Lars
    Software architecture: Engineering quality attributes2003In: Journal of Systems and Software, ISSN 0164-1212 , Vol. 66, no 3, p. 183-186Article in journal (Refereed)
  • 67. Bosch, Jan
    et al.
    Molin, Peter
    Software architecture design: Evaluation and transformation1999Conference paper (Refereed)
    Abstract [en]

    Since the architecture of a software system constrains the quality attributes, the decisions taken during architectural design have a large impact on the resulting system. An architectural design method is presented that employs iterative evaluation and transformation of the software architecture in order to satisfy the quality requirements. Architecture evaluation is performed by using scenarios, simulation, mathematical modelling and experience-based reasoning. The architecture can be transformed by imposing an architectural sg le, imposing an architectural pattern, using a design pattern, converting a quality requirement to functionality and by distributing quality requirements. The method has evolved through its application in several industrial projects.

  • 68. Bosch, Jan
    et al.
    Szyperski, ClemensWeck, Wolfgang
    Proceedings of the Fifth International Workshop on Component-Oriented Programming (WCOP 2000)2000Report (Other academic)
    Abstract [en]

    WCOP 2000, held in conjunction with ECOOP 2000 in Sophia Antipolis, France, was the fifth workshop in the successful series of workshops on component-oriented programming. The previous workshops were held in conjunction with the respective ECOOP conferences in Linz, Austria, Jyväskylä, Finland, Brussels, Belgium and Lisbon, Portugal. WCOP96 had focused on the principal idea of software components and worked towards definitions of terms. In particular, a high-level definition of what a software component is was formulated. WCOP97 concentrated on compositional aspects, architecture and gluing, substitutability, interface evolution, and non-functional requirements. WCOP98 had a closer look at issues arising in industrial practice and developed a major focus on the issues of adaptation. WCOP'99 moved on to address issues of component frameworks, structured architecture, and some bigger systems built using components frameworks. The topics for WCOP 2000 focused on component composition, validation and refinement and the use of component technology in the software industry.

  • 69. Bosch, Jan
    et al.
    Szyperski, Clemens
    Weck, Wolfgang
    WCOP '98: Summary of the Third International Workshop on Component-Oriented Programming1998Conference paper (Refereed)
  • 70. Bosch, Jan
    et al.
    Szyperski, ClemensWeck, Wolfgang
    WCOP ´99: Proceedings of the Fourth International Workshop on Component-Oriented Programming1999Report (Other academic)
    Abstract [en]

    WCOP'99 is the fourth event in a series of highly successful workshops, which took place in conjunction with every ECOOP since 1996, focusing on the important field of component-oriented programming (COP). COP has been described as the natural extension of object-oriented programming to the realm of independently extensible systems. Several important approaches have emerged over the recent years, including CORBA, COM (COM+, DCOM, ActiveX, DirectX, ...), JavaBeans. A component is not an object, but provides the resources to instantiate objects. Often, a single component will provide interfaces to several closely related classes. Hence, COP is about architecure and packaging, besides interoperation between objects. After WCOP'96 focused on the fundamental terminology of COP, the subsequent workshops expanded into the many re- lated facets of component software. WCOP'99 shall emphasis architectural design and construction of component-based systems beyond ad-hoc reuse of unrelated components. To enable lively and productive discussions, the workshop will be limited to 25 participants. Depending on the actually submitted positions papers, the workshop will be organized into three or four subsequent mini-sessions, each initiated by a presentation of two or three selected positions and followed by discussions. Instead of splitting the workshop into task forces, it is intended to provoke lively discussion by preparing lists of critical questions and some, perhaps provocative, statements (to be used on demand). Position papers will be formally reviewed, each by at least two independent reviewers. As an incentive for submission of high quality statements, the best position statements will be combined with transcripts of workshop results and published.

  • 71.
    Boström, Stellan
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Integrating Push Technology with the Ericsson Mobile Positioning Center2001Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Push is an Internet technology, which allow people to subscribe to a content- or service provider that automatically update the subscriber?s computer or Personal Digital Assistant (PDA) with the latest information without having the subscriber to first request for new information. The Ericsson Mobile Positioning Center (MPC) is a gateway that provides geographical positions of mobile stations to various applications. This Master Thesis gives the reader an overview of these technologies and presents an alternative way in integrating a third part Push-solution with the MPC. The integration proposal is also evaluated against the current Push functionality that Ericsson has developed and integrated into the MPC.

  • 72. Bousquet, Francois
    et al.
    Davidsson, PaulSichman, Jaime
    Multi-Agent Based Simulation2002Collection (editor) (Other academic)
  • 73.
    Brandao, Ligia C
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Lennartsson, Ewonne
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Elektroniska signaturer- säker identifiering?2001Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Problem:I dag finns det ett stort behov av säkra identifierings metoder på Internet. Traditionellt sätt är en handskriven namnteckning en form av identifiering och vad som behövs är en elektronisk motsvarighet. Hypotes: "Elektroniska signaturer leder till ökad integritet och säkerhet vid identifiering på Internet" Syfte: Målet och syftet med denna uppsats är att studera och analysera huruvida elektroniska signaturer kommer att bidra till ökad integritet och säkerhet vid identifiering på Internet. Slutsats:Genom att jämföra praktiska erfarenheter (fallstudie) och teoretiska kriterier kunde vi analysera oss fram till att vår hypotes är sann.

  • 74. Brazier, Frances
    et al.
    Cornelissen, Frank
    Gustavsson, Rune
    Jonker, Catholijn M.
    Lindeberg, Olle
    Polak, Bianca
    Treur, Jan
    Compositional Design and Verification of a Multi-Agent System for One-to-Many Negotiation1998Conference paper (Refereed)
    Abstract [en]

    A compositional verification method for multi-agent systems is presented and applied to a multi-agent system for one-to-many negotiation in the domain of load balancing of electricity use. Advantages of the method are that the complexity of the verification process is managed by compositionality, and that part of the proofs can be reused in relation to reuse of components.

  • 75. Broberg, Hanna
    et al.
    Petrakou, Alexandra
    Zhang, Peng
    Révay, Péter
    A systematic approach to Activity Theory in practice2003Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to integrate social psychology and systems thinking by expanding Soft Systems Methodology (SSM) with Activity Theory (AT). Problems in the health care system are always very complex and Information Technology is usually considered to be a part of the solution. Our interest for research is in the area of elderly care, which consists of both health care and service efforts. These efforts are at some counties divided between two parties, municipality and county council. This implies a need for cooperation, communication and coordination. When this fails it affects the whole system. The problem situation must be seen as a holistic system problem but it is also essential to consider the individuals involved in the two systems and their socio-psychological environment. As a systems methodology, SSM, emphasizes the information processing and provides a methodology for solving the “soft” situations. AT, on the other hand, provides an approach for understanding the human activities in their context. With this perspective, we expanded SSM by integrating AT from two points and also introduced the concept of contradictions from Activity Theory as a way to compare the real world with the conceptual model. In the third stage of SSM, we use the six components of AT as a complement to the root definitions, CATWOE[1], given by Checkland. CATWOE provides comprehensive definitions about the system’s developmental variables, whereas the components in the AT model further focuses on the socio-psychological factors. In the fourth stage, we use the triangle model of AT as the basic element to build up a ‘conceptual model’. The focus of this paper is on the possibilities of combining SSM with AT, which resulted in a satisfying and reasonably effective method to analyze the home care service[2].

  • 76. Broberg, Magnus
    Performance Prediction and Improvement Techniques for Parallel Programs in Multiprocessors2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The performance of a computer system is important. One way of improving performance is to use multiprocessors with several processors that can work in parallel. Where multiprocessors are used, the programs must also be parallel in order to achieve high performance. However, it is not always easy to write parallel programs for multiprocessors; program developers need support in this area. Such support includes, for example, information regarding how well the parallel program scales-up when the number of processors increases and identification of performance bottlenecks; ideally, the result should be presented graphically. Bottlenecks arise both as a result of parallelization as well as traditional (sequential) code. Further, the developer may need to predict performance on other systems than the one used for development, since the development environment often is the (uni-processor) workstation on the developer's desk. One way of increasing the performance may be to bind threads on processors statically. Finding the optimal allocation is NP-hard and it is necessary to resort to heuristic algorithms. When heuristic algorithms are used we do not know how near/far we are from the optimal allocation. Finding a bound for the program's completion time shows what should be achievable using a heuristic algorithm. In this thesis, I present techniques how to simulate a multiprocessor execution of a parallel program based on a monitored execution on a uni-processor. The result of the (simulated) multiprocessor execution is graphically presented in order to give feedback to the developer. The techniques can be used for heuristic algorithms to find an allocation of threads to processors. Further, I show an algorithm that identifies the critical path of the parallel program on a multiprocessor, thereby identifying the segments that are worthwhile optimizing. I also show how to calculate a tight bound on the minimal completion time for the optimal allocation of threads to processors. Finally, I discuss the implications of the choice of simulation model. The techniques and algorithms described have been manifested in a prototype tool which I have used to perform empirical studies. The tool has been validated using a real multiprocessor.

  • 77. Broberg, Magnus
    Performance tuning of multithreaded applications for multiprocessors by cross-simulation2000Conference paper (Refereed)
    Abstract [en]

    Performance tuning of a parallel application is often hard. The use of standards such as POSIX threads, makes it possible to move a multithreaded application from one platform to another. Doing performance tuning for many platforms is even tougher since the implementation of the standards may vary on different operating systems. The developer needs tools for analysing how the application will behave on different operating systems in order to do adequate performance tuning. In this paper we present a technique based on cross-simulation that will solve the issues above. The technique uses a monitored execution of a multithreaded application on a single processor workstation running the Solaris operating system. Then the technique, which has been implemented in a tool, simulates a multiprocessor with an arbitrary number of processors running either Solaris or Linux. The tool then displays the behaviour of the application on the selected target configuration. Validation, using a subset of the SPLASH-2 benchmark suite, shows that the tool predicts speed-ups correctly. The average error in the predicted speed-up when simulating Linux is 5.8%. All this can be done using the ordinary Solaris workstation on the developer's desk, without even having a multiprocessor.

  • 78. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    A Tool for Binding Threads to Processors2001Conference paper (Refereed)
    Abstract [en]

    Many multiprocessor systems are based on distributed shared memory. It is often important to statically bind threads to processors in order to avoid remote memory access, due to performance. Finding a good allocation takes long time and it is hard to know when to stop searching for a better one. It is sometimes impossible to run the application on the target machine. The developer needs a tool that finds the good allocations without the target multiprocessor. We present a tool that uses a greedy algorithm and produces allocations that are more than 40% faster (in average) than when using a binpacking algorithm. The number of allocations to be evaluated can be reduced by 38% with a 2% performance loss. Finally, an algorithm is proposed that is promising in avoiding local maxima.

  • 79. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    An Allocation Strategy Using Shadow-processors and Simulation Technique2001Conference paper (Refereed)
    Abstract [en]

    Efficient performance tuning of parallel programs for multiprocessors is often hard. When it comes to assigning threads to processors there is not much support from commercial operating systems, like the Solaris operating system. The only known value is, in best case, the total execution time of each thread. The developer is left to the bin packing algorithm with no knowledge about the interactions and dependencies between the threads. The bin packing algorithm assigns, in the worst case, the threads to the processors such that the program will have the longest possible execution time. A simple example of such a program is shown. We present here a way of retrieving more information and a test mechanism that makes it possible to compare two different assignments of threads on processors also with regard to the interactions and dependencies between the threads. Also an algorithm is proposed that gives the best assignment of threads to processors in the case above where the bin packing algorithm gave the worst possible assignment. The algorithm uses shadow-processors and requires more processors than on the target machine during some allocation steps. Thus, a simulation tool like the one presented here must be used.

  • 80. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    Performance Optimization using Critical Path Analysis in Multithreaded Programs on Multiprocessors1999Report (Other academic)
    Abstract [en]

    Efficient performance tuning of parallel programs is often hard. Optimization is often done when the program is written as a last effort to increase the performance. With sequential programs each (executed) code segment will affect the total execution time of the program. Thus, any code segment that is optimized in a sequential program will decrease the execution time. In the case of a parallel program executed on a multiprocessor this is not always true. This is due to dependencies between the different threads. As a result, certain code segments of the execution may not affect the total execution time of the program. Thus, optimization of such code segments will not increase the performance. In this paper we present a new approach to perform the optimization phase. Our approach finds the critical path of the multithreaded program and the optimization is only done on those specific code segments of the program. We have implemented the critical path analysis in a performance optimization tool.

  • 81.
    Broberg, Magnus
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Lundberg, Lars
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Grahn, Håkan
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Performance Optimization using Extended Critical Path Analysis in Multithreaded Programs on Multiprocessors2001In: Journal of Parallel and Distributed Computing, ISSN 0743-7315, Vol. 61, no 1, p. 115-136Article in journal (Refereed)
  • 82. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    Selecting simulation models when predicting parallel program behavior2002Conference paper (Refereed)
    Abstract [en]

    The use of multiprocessors is an important way to increase the performance of a parallel program. This means that. the program has to be parallelized to make use of the multiple processors. The parallelization is unfortunately not an easy task. Development tools supporting parallel programs are important. Further, it is the customer that decides the number of processors in the target machine, and as a result the developer has to make sure that the program runs efficiently on any number of processors. Many simulation tools support the developer by simulating any number of processors and predict the performance based on a uniprocessor execution trace. This popular technique gives reliable results in many cases. Based on our experience from developing such a tool, and studying other (commercial) tools, we have identified three basic simulation models. Due to the flexibility of general purpose programming languages and operating systems, like C/C++ and Sun Solaris, two of the models may cause deadlock in a deadlock-free program. Selecting the appropriate model is difficult, we show that the three models have significantly different accuracy when using real world programs. Based on the findings we present a practical scheme when to use the models.

  • 83. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    Selecting Simulation Models when Predicting Parallel Program Behaviour.2002Conference paper (Refereed)
  • 84. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    Selecting Simulation Models when Predicting Parallel Program Behaviour2002Report (Other academic)
    Abstract [en]

    The use of multiprocessors is an important way to increase the performance of a supercom-puting program. This means that the program has to be parallelized to make use of the multi-ple processors. The parallelization is unfortunately not an easy task. Development tools supporting parallel programs are important. Further, it is the customer that decides the number of processors in the target machine, and as a result the developer has to make sure that the pro-gram runs efficiently on any number of processors. Many simulation tools support the developer by simulating any number of processors and predict the performance based on a uni-processor execution trace. This popular technique gives reliable results in many cases. Based on our experience from developing such a tool, and studying other (commercial) tools, we have identified three basic simulation models. Due to the flexibility of general purpose programming languages and operating systems, like C/C++ and Sun Solaris, two of the models may cause deadlock in a deadlock-free program. Selecting the appropriate model is difficult, since we in this paper also show that the three models have significantly different accuracy when using real world programs. Based on the findings we present a practical scheme when to use the three models.

  • 85. Broberg, Magnus
    et al.
    Lundberg, Lars
    Grahn, Håkan
    Visualization and performance prediction of multithreaded Solaris programs by tracing kernel threads1999Conference paper (Refereed)
    Abstract [en]

    Efficient performance tuning of parallel programs is often hard. We present a performance prediction and visualization tool called VPPB. Based on a monitored uni-processor execution, VPPB shows the (predicted) behaviour of a multithreaded program using any number of processors and the program behaviour is visualized as a graph. The first version of VPPB was unable to handle I/O operations. This version has, by an improved tracing technique, added the possibility to trace activities at the kernel level as well. Thus, VPPB is now able to trace various I/O activities, e.g., manipulation of OS internal buffers, physical disk I/O, socket I/O, and RPC. VPPB allows flexible performance tuning of parallel programs developed for shared memory multiprocessors using a standardized environment; C/C++ programs that lues the thread package in Solaris 2.X.

  • 86. Broberg, Magnus
    et al.
    Lundberg, Lars
    Klonowska, Kamilla
    A Method for Bounding the Minimal Completion Time in Multiprocessors2002Report (Other academic)
    Abstract [en]

    The cluster systems used today usually prohibit that a running process on one node is reallocated to another node. A parallel program developer thus has to decide how processes should be allocated to the nodes in the cluster. Finding an allocation that results in minimal completion time is NP-hard and (non-optimal) heuristic algorithms have to be used. One major drawback with heuristics is that we do not know if the result is close to optimal or not. In this paper we present a method for finding a guaranteed minimal completion time for a given program. The method can be used as a bound that helps the user to determine when it is worth-while to continue the heuristic search. Based on some parameters derived from the program, as well as some parameters describing the hardware platform, the method produces the minimal completion time bound. The method includes an aggressive branch-and-bound algorithm that has been shown to reduce the search space to 0.0004%. A practical demonstration of the method is presented using a tool that automatically derives the necessary program parameters and produces the bound without the need for a multiprocessor. This makes the method accessible for practitioners.

  • 87.
    Broman, Peter
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Liljerum, Ola
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    En jämförelse av krypteringsalgoritmer2001Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Today the Internet is used more and more as a transportation for information. Much of the information is confidential and should not be read by those not privileged. To protect the information from unauthorized access cryptography can be applied. The cryptography algorithms in use today all have their pros and cons. They are therefore suited for different applications. We've compared three different cryptography algorithms RSA, DES and IDEA. What we've focused on is the level of security the algorithms give. DES and IDEA are symmetrical algorithms and as such they use the same key for encryption and decryption. RSA on the other hand is an asymmetrical algorithm. Asymmetrical algorithms use two keys, one for encryption and the other for decryption. The factor that is most decisive for the algorithms security is the length of the key that is used. What is interesting concerning the keys is that security increases linearly for the symmetrical algorithms, as the key length increases. For asymmetrical algorithms it increases on an expontiell curve. RSA has got a big advantage compared to DES and IDEA. The advantage is key management. RSA can be used to exchange symmetrical keys in a safe way. The big disadvantage of RSA is that it's very slow to use. According to measurements that we have seen it is about 3 to 4 times slower then DES and IDEA during encryption, when using a key length of 1024 bits. At decryption RSA is about 120 times slower using a key length of 1024 bits. DES on the other hand is slower then newer symmetrical algorithms such as IDEA. This makes it uncalled for to use it in it?s original shape as it?s obsolete and insecure. Using DES will only give a false sense of security, unless the information doesn't need to be secure for more then a short time period. IDEA offers high using it's 128 bits key and it's also the fastest of the two symmetrical algorithms, compared to the level of security that it offers. IDEA today has no known weaknesses and it has not been broken. Of the three IDEA is the best choice to use when it concerns cryptography of information, for example information which is stored on a hard disc, or information that is sent in e-commerce.

  • 88. Buisman, J.
    et al.
    Wohlin, Claes
    Using Game Theory to Study Bidding for Software Projects2003Conference paper (Refereed)
  • 89.
    Buisman, Jacco
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Game Theory and Bidding for Software Projects An Evaluation of the Bidding Behaviour of Software Engineers2002Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The conception phase is one of the most important phases of software projects. In this phase it is determined which software development company will perform a software project. To obtain a software project, companies can have several bidding strategies. This thesis investigates if and how game theory can be a helpful tool to evaluate bidding for software projects. This thesis can be divided into two different parts: a theoretical and a practical. The theoretical part investigates the applicable parts of game theory in this thesis, explains what software projects are, explains the difference between costing and bidding and provides results of a literature survey about bidding behaviour. The practical part introduces a study to investigate strategies and bidding behaviour of software engineers, explains the experimental design that found the study, provides the results of the performed study and a discussion of the results. This thesis concludes that game theory contains some concepts that make it possible to evaluate bidding for software projects.

  • 90.
    Carlsson, Anders
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    A guideline for evaluating OODBMSs2003Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Object oriented databases have been around since the late 1980’s. Object oriented programming languages have been around since the sixties. Today the need for object oriented databases is growing along with the complexity of the software systems developed. There are today a number of object oriented databases available on the market. The apabilities and properties of the systems are covering a wide range, making the choice of system difficult to the developer. This thesis presents a guideline for evaluating object oriented database management systems to be able to compare different systems and chose which one to use.

  • 91.
    Carlsson, Anders
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Object oriented databases: a natural part of object oriented software development?2003Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    The technology of object oriented databases was introduced to system developers in the late 1980?s. Despite that it is rarely used today. This thesis introduces the concept of object oriented databases as the purposed solution to the problems that exist with the use of relational databases. The thesis points to the advantages with storing the application objects in the database without disassembling them to fit a relational data model. Based on that advantages and the cost of introducing such a rarely used technology into a project, a guideline for when to use object oriented databases and when to use relational databases is given.

  • 92. Carlsson, Bengt
    Conflicts in Information Ecosystems2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main topic of this thesis concerns the study of how conflicting interests of software agents within an information ecosystem may cause cooperative behavior. Since such agents act on the behalf of their human owners, which often act in their own interest, this will sometimes result in malignant acts. Different types of models, often inspired by biological theories such as natural selection, will be used to describe various aspects of such information ecosystems. We begin by adopting a game theoretic approach where a generous and greedy model is introduced. Different agent strategies for iterated games are compared and their ability to cooperate in conflicting games are evaluated in simulation experiments. The conclusion is that games like the chicken game favor more complex and generous strategies whereas in games like the prisoner’s dilemma, the non-generous strategy tit-for-tat often is the most successful. We then use models based on a surplus value concept to explain antagonistic group formations. The focus is on systems that consist of exploiter agents and agents being exploited. A dynamic protection model of access control is proposed, where a chain of attacks and countermeasures concerning the access are measured. This process can be described as an arms race. It is argued that arms race is a major force in the interaction between antagonistic agents within information ecosystems. Examples of this are given in several contexts such as peer-to-peer tools concerning anonymity and non-censorship, using agents for sending or filtering out mass distributed advertisement e-mails, and finally for describing the fight against viruses or spywares.

  • 93. Carlsson, Bengt
    Simulating how to Cooperate in Iterated Chicken Game and Iterated Prisoner's dilemma2001In: Agent Engineering, Series in Machine Perception and Artificial Intelligence / [ed] Liu, Jiming; Tang, Yuan Y; Zhong, Ning; Wang, Patric S P, World Scientific , 2001Chapter in book (Other academic)
  • 94. Carlsson, Bengt
    The Tragedy of the Commons: Arms Race Within Peer-to-Peer Tools2001Conference paper (Refereed)
    Abstract [en]

    The two major concerns about peer-to-peer are anonymity and non-censorship of documents. Music industry has highlighted these questions by forcing Napster to filter out copyright protected MP3 files and taking legal actions against local users by monitoring their stored MP3 files. Our investigation shows that when copyright protected files are filtered out, users stop downloading public music as well. The success of a distributed peer-to-peer system is dependent on both cooperating coalitions and an antagonistic arms race. An individual will benefit from cooperation if it is possible to identify other users and the cost for managing services is negligible. An arms race between antagonistic participants using more and more refined agents is a plausible outcome. Instead of “the tragedy of the common” we are witnessing “the tragedy of arms race within the common”. Arms race does not need to be a tragedy because these new tools developed or actions taken against too selfish agents may improve the peer-to-peer society.

  • 95. Carlsson, Bengt
    et al.
    Davidsson, Paul
    A biological View on Information Ecosystems2001Conference paper (Refereed)
    Abstract [en]

    When comparing information ecosystems to biological ecosystems, it becomes clear that both types of systems seem to support robust solutions that are hard to violate for a single agent. In the analysis of information ecosystems, it is important to take into consideration that agents may have a Machiavellian intelligence, i.e., that they take the self-interest of other agents into consideration. We conclude that in the interaction between antagonistic agents within information systems, arms race is a major force. A positive result of this is a better readiness for innocent agents against the vigilant agents. Some examples are given to show how the modelling of information ecosystems in this way can explain the origin of more robust systems when antagonistic agents are around.

  • 96. Carlsson, Bengt
    et al.
    Davidsson, Paul
    Surplus Values in Information Ecosystems2002In: International Journal of Information Technology and Decision Making, ISSN 0219-6220 , Vol. 1, no 3, p. 559-571Article in journal (Refereed)
    Abstract [en]

    A model of surplus values within information ecosystems is presented. The model is based on the classical definition of surplus value. However, as this definition was developed within a manufacturing industry context, some modifications are necessary to adopt it to the context of information ecosystems, e.g. by taking into account that products are "virtual" rather than physical. Just as in agent-based computational economics, here the economics is modelled as evolving systems of autonomous interacting agents in an evolutionary framework. In this way the resulting model is able to capture more dynamic scenarios. The model is formally specified in terms of price, profit, and group gaining functions and is applied to some examples of societies of selfish agents in antagonistic groups to illustrate its dynamic properties. Moreover, the paper show how the model builds upon labour theory of value and contrasts it to consumer value models.

  • 97. Carlsson, Bengt
    et al.
    Gustavsson, Rune
    Arms Race Within Information Ecosystems2001In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 2182, p. 202-207Article in journal (Refereed)
    Abstract [en]

    Interacting agents of exploiters and users within an information ecosystem may be regarded both as biological beings and as part of an economic system of infohabitants. A protection system can be implemented as a filter governing the access to assets. Typically we will have a chain of attacks and countermeasures concerning this access to the desired assets. We model this process as an arms race. We base our model on a process model of a protection system based on exposure time. A user's reaction against an exploiter measure could either be a direct response to the measure or an attempt to anticipate future attacks by more general means of defeating the protection of the exploiter agent. When anticipating future attacks and countermeasures, both users and exploiters will improve their methods and tools due to an arms race. Our arms race model refines the competition as modeled in computational markets to model aspects which typically arise when societies grow beyond what can be controlled in a centralized manner. A dynamic, evolving and robust ecosystem of autonomous agents is sometimes a preferred and possible outcome of the arms race as a hardening process.

  • 98. Carlsson, Bengt
    et al.
    Gustavsson, Rune
    The rise and fall of Napster-an evolutionary approach2001Conference paper (Refereed)
    Abstract [en]

    The paper addresses dynamics in information ecosystems due to competition between selfish agents to get control of protectable resources. In our case study we investigate the first arms race on Internet triggered by the Napster introduction of an easy to use service for sharing files with music content among users. We set up a model for investigation of possible scenarios emerging from the Napster and Gnutella peer-to-peer tools for information sharing. We also introduce a formal model for analyzing the Napster scenario in the cases of selfish or altruistic users. The prediction provided by our model is in line with what really happened in the Napster case. The model also shows that the outcome was indeed unavoidable if we have selfish users.

  • 99. Carlsson, Bengt
    et al.
    Jönsson, Ingemar
    Differences between the iterated Prisoner´s dilemma and the Chicken game under noisy conditions.2002Conference paper (Refereed)
    Abstract [en]

    The prisoner's dilemma has evolved into a standard game for analyzing the success of cooperative strategies in repeated games. With the aim of investigating the behavior of strategies in some alternative games we analyzed the outcome of iterated games for both the prisoner's dilemma and the chicken game. In the chicken game, mutual defection is punished more strongly than in the prisoner's dilemma, and yields the lowest fitness. We also ran our analyses under different levels of noise. The results reveal a striking difference in the outcome between the games. Iterated chicken game needed more generations to find a winning strategy. It also favored nice, forgiving strategies able to forgive a defection from an opponent. In particular the well-known strategy tit-for-tat has a poor successrate under noisy conditions. The chicken game conditions may be relatively common in other sciences, and therefore we suggest that this game should receive more interest as a cooperative game from researchers within computer science.

  • 100.
    Carlsson, Jimmy
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    A practical approach toward architectures for open computational systems2002Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    By means of a systemic approach toward analysis and design of complex systems, we introduce the issue of implementing open computational systems on service-oriented architectures. We start by studying general systems theory, as it accounts for analysis and modeling of complex systems, and then compare three different implementation strategies toward system implementation. As such, the comparison is grounded in the notion of supporting architectures and, more specifically, in the practical case of a service-oriented layered architecture for communicating entities (SOLACE).

1234567 51 - 100 of 454
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf