Diss. Linköping : Univ., 2001.

Diss. (sammanfattning) Sundsvall : Mittuniversitetet, 2010.

Diss. Västerås : Mälardalens högskola, 2009.

Diss. [Sammanfattning] Luleå : Luleå tekniska universitet, 2008. / Härtill 5 uppsatser.

<p>Cooperative Software Engineering (CSE) means that large-scale, software development and maintenance can be conducted in a distributed organisation or across organisations. CSE can be characterised by distributed process fragments, partly shared workspaces, cooperation planning, and frequent interactions in intra/inter-workspaces. To support CSE processes, we must deal with dynamic, unpredictable processes as well as stable, repeatable processes with totally different characteristics. Traditional workflow and process systems offer good support for stable, pre-planned processes, providing user agendas, invocation of tools, presentation of process state etc. Multi-agent systems are well suited to model and support users involved in cooperative processes. By combining these two technologies, processes with characteristics similar to cooperative software engineering processes can be modelled and supported more completely.</p><p>The thesis presents a framework called CAGIS Process Centred Environment (PCE), for combining a workflow system with a multi-agent system. These are the main parts of the thesis:</p><p>- A multi-agent architecture to support cooperative processes. This architecture is particularly useful in modelling and providing support for cooperative activities where software agents act on behalf of the user. The design and implementation of this architecture is described.</p><p>-A workflow system to support distributed mobile processes. This workflow system allows processes to be fragmented into smaller sub-processes that can be distributed over several workspaces and moved between these workspaces.</p><p>-A gluing framework to specify the interaction between the workflow system and the multi-agent architecture. The gluemodel defines the relationships between software agents and process fragments (sub-processes), and a GlueServer is used as a middleware between a workflow tool and a multi-agent system. Results from applying the GlueModel framework on a cooperative software engineering (CSE) process is also described.</p><p>- A Evaluation of the framework by modelling three practical cases:</p><p>- A conference organising process is modelled in three different process environments (including our own), and evaluated according to modelling completeness and adaptability to process changes.</p><p>- A CSE scenario describing a software and maintenance process in a Norwegian software company is modelled to show usefulness of the gluing framework.</p><p>- A project organisation scenario used to demonstrate how software agents can be used in CAGIS Process Centred Environment to deal with evolution of distributed, fragmented workflow models.</p>

<p>Worst-Case Execution Time (WCET) estimates for programs are necessary when building real-time systems. They are used to ensure timely responses from interrupts, to guarantee the throughput of cyclic tasks, as input to scheduling and schedule analysis algorithms, and in many other circumstances. Traditionally, such estimates have been obtained either by measurements or labor-intensive manual analysis, which is both time consuming and error-prone. Static worst-case execution time analysis is a family of techniques that promise to quickly provide safe execution time estimates for real-time programs, simultaneously increasing system quality and decreasing the development cost. This thesis presents several contributions to the state-of-the-art in WCET analysis.</p><p>We present an overall architecture for WCET analysis tools that provides a framework for implementing modules. Within the stable interfaces provided, modules can be independently replaced, making it easy to customize a tool for a particular target and perform performance-precision trade-offs. </p><p>We have developed concrete techniques for analyzing and representing the timing behavior of programs running on pipelined processors. The representation and analysis is more powerful than previous approaches in that pipeline timing effects across more than pairs of instructions can be handled, and in that no assumptions are made about the program structure. The analysis algorithm relies on a trace-driven processor simulator instead of a special-purpose processor model. This allows us to use existing simulators to adapt the analysis to a new target platform, reducing the retargeting effort. </p><p>We have defined a formal mathematical model of processor pipelines, which we use to investigate the properties of pipelines and WCET analysis. We prove several interesting properties of processors with in-order issue, such as the freedom from timing anomalies and the fundamental safety of WCET analysis for certain classes of pipelines. We have also constructed a number of examples that demonstrate that tight and safe WCET analysis for pipelined processors might not be as easy as once believed. </p><p>Considering the link between the analysis methods and the real world, we discuss how to build accurate software models of processor hardware, and the conditions under which accuracy is achievable.</p>

<p>In this dissertation, we present two new sorts of computer sciencelogics.</p><p>Many powerful logics exist today for reasoning about multi-agentsystems, but in most of these it is hard to reason about an infiniteor indeterminate number of agents. Also the naming schemes used inthe logics often lack expressiveness to name agents in an intuitiveway.</p><p>To obtain a more expressive language for multi-agent reasoning and abetter naming scheme for agents, we introduce in the first part of thedissertation a family of logics called term-modal logics. A mainfeature of our logics is the use of modal operators indexed by theterms of the logics. Thus, one can quantify over variables occurringin modal operators. In term-modal logics agents can be represented byterms, and knowledge of agents is expressed with formulas within thescope of modal operators.</p><p>This gives us a flexible and uniform language for reasoning about theagents themselves and their knowledge. We give examples of theexpressiveness of the languages and provide sequent-style andtableau-based proof systems for the logics. Furthermore, we giveproofs of soundness and completeness with respect to the possibleworld semantics.</p><p>In the second part of the dissertation, we treat another problem inreasoning about multi-agent systems, namely the problem of informationupdating. We develop a dynamic logic of assignments with a scopingoperator instead of quantifiers. Function, relation symbols and logicvariables are all rigidly interpreted in our semantics, while programvariables are non-rigid. The scoping operator is used to distinguishbetween the value of a program variable before and after the executionof a program.</p><p>We provide a tableau proof system for the logic. First, the system isproved complete without the star operator, and then with the staroperator using an omega rule. The full logic is shown to beundecidable, while some interesting fragments are decidable.</p>

Cooperative Software Engineering (CSE) means that large-scale, software development and maintenance can be conducted in a distributed organisation or across organisations. CSE can be characterised by distributed process fragments, partly shared workspaces, cooperation planning, and frequent interactions in intra/inter-workspaces. To support CSE processes, we must deal with dynamic, unpredictable processes as well as stable, repeatable processes with totally different characteristics. Traditional workflow and process systems offer good support for stable, pre-planned processes, providing user agendas, invocation of tools, presentation of process state etc. Multi-agent systems are well suited to model and support users involved in cooperative processes. By combining these two technologies, processes with characteristics similar to cooperative software engineering processes can be modelled and supported more completely. The thesis presents a framework called CAGIS Process Centred Environment (PCE), for combining a workflow system with a multi-agent system. These are the main parts of the thesis: - A multi-agent architecture to support cooperative processes. This architecture is particularly useful in modelling and providing support for cooperative activities where software agents act on behalf of the user. The design and implementation of this architecture is described. -A workflow system to support distributed mobile processes. This workflow system allows processes to be fragmented into smaller sub-processes that can be distributed over several workspaces and moved between these workspaces. -A gluing framework to specify the interaction between the workflow system and the multi-agent architecture. The gluemodel defines the relationships between software agents and process fragments (sub-processes), and a GlueServer is used as a middleware between a workflow tool and a multi-agent system. Results from applying the GlueModel framework on a cooperative software engineering (CSE) process is also described. - A Evaluation of the framework by modelling three practical cases: - A conference organising process is modelled in three different process environments (including our own), and evaluated according to modelling completeness and adaptability to process changes. - A CSE scenario describing a software and maintenance process in a Norwegian software company is modelled to show usefulness of the gluing framework. - A project organisation scenario used to demonstrate how software agents can be used in CAGIS Process Centred Environment to deal with evolution of distributed, fragmented workflow models.

Distributed programming is usually considered both difficult and inherently different from concurrent centralized programming. It is thought that the distributed programming systems that we ultimately deploy, in the future, when we've worked out all the details, will require a very different programming model and will even need to be evaluated by new criteria. The Mozart Programming System, described in this thesis, demonstrates that this need not be the case. It is shown that, with a good system design, distributed programming can be seen as an extended form of concurrent programming. This is from the programmer's point-of-view; under the hood the design and implementation will necessarily be more complex. We relate the Mozart system with the classical transparencies of distributed systems. We show that some of these are inherently on the application level, while as Mozart demonstrates, others can and should be dealt with on the language/system level. The extensions to the programming model, given the right concurrent programming base, are mainly concerned with non-functional properties of programs. The models and tuning facilities for failure and performance need to take latency, bandwidth, and partial failure into account. Other than that there need not be any difference between concurrent programming and distributed programming. The Mozart Programming System is based on the concurrent programming language Oz, which integrates, in a coherent way, all three known concurrency or thread-interaction models. These are message-passing (like Erlang), shared objects (like Java with threads) and shared data-flow variables. The Mozart design philosophy is thus applicable over the entire range of concurrent programming languages/systems. We have extracted from the experience with Mozart a number of principles and properties that are applicable to the design and implementation of all (general-purpose) distributed programming systems. The full range of the design and implementation issues behind Mozart are presented. This includes a description of the consistency protocols that make transparency possible for the full language, including distributed objects and distributed data-flow variables. Mozart is extensively compared with other approaches to distributed programming, in general, and to other language-based distributed programming systems, in particular / QC 20100928

Diss. Linköping : Univ.