Consistency Maintenance of Group/Ungroup Operations in Object-based Collaborative Graphical Editing Systems

In real-time collaborative graphical editing systems, Object-based Group/Ungroup operations are frequently accessible and practically useful. However, the existing research on these operations of the graphical editing is rare and defective. In this paper, based on Multi-Version strategy and Address Space Transformation method, a new MVSDR algorithm, which is not only applied to simple operations (such as Create, Delete, ChangeATT, etc.), but also suitable for Group/Ungroup ones, is proposed to solve the consistency maintenance problem. The proposed algorithm abandons previous attempts to divide conflict operations into Real-Conflict operations and Resolvable-Conflict ones and to deal with them separately, thus making the algorithm more simple and effective. In addition, an example analysis is also given in this paper to prove the algorithm’s correctness and effectiveness

Computer-Supported Collaborative Production

This paper proposes the concept of collaborative production as a focus of concern within the general area of collaborative work. We position the concept with respect to McGrath's framework for small group dynamics and the more familiar collaboration processes of awareness, coordination, and communication (McGrath 1991). After reviewing research issues and computer-based support for these interacting aspects of collaboration, we turn to a discussion of implications for how to design improved support for collaborative production. We illustrate both the challenges of collaborative production and our design implications with a collaborative map-updating scenario drawn from the work domain of geographical information systems

Figure 1. Aquamarine's History Panel showing operation #10 (brush stroke for the nose) selectively undone. Selective Undo Support for Painting Applications

ABSTRACT Today's widely deployed painting applications use a linear undo model that allows users to backtrack previous operations in reverse chronological order. This undo model is not useful if the user has performed desired operations after undesired ones. Selective undo, in contrast, allows users to select specific operations in the past and only undo those, while keeping the remaining operations intact. Although selective undo has been widely explored in the context of text editing and object-oriented drawing, we explore selective undo for painting (bitmap) editing, which has received less attention and introduces many interesting user interface design challenges. Our system, called Aquamarine, explores the script model for selective undo, where selectively undone operations are skipped in the history, rather than the more explored inverse model, which puts an inverse of the selected operations at the end of the history. We discuss the design implications and show through two informal user studies that selective undo is usable and desirable

Towards Collaborative Scientific Workflow Management System

The big data explosion phenomenon has impacted several domains, starting from research areas to divergent of business models in recent years. As this intensive amount of data opens up the possibilities of several interesting knowledge discoveries, over the past few years divergent of research domains have undergone the shift of trend towards analyzing those massive amount data. Scientific Workflow Management System (SWfMS) has gained much popularity in recent years in accelerating those data-intensive analyses, visualization, and discoveries of important information. Data-intensive tasks are often significantly time-consuming and complex in nature and hence SWfMSs are designed to efficiently support the specification, modification, execution, failure handling, and monitoring of the tasks in a scientific workflow. As far as the complexity, dimension, and volume of data are concerned, their effective analysis or management often become challenging for an individual and requires collaboration of multiple scientists instead. Hence, the notion of 'Collaborative SWfMS' was coined - which gained significant interest among researchers in recent years as none of the existing SWfMSs directly support real-time collaboration among scientists. In terms of collaborative SWfMSs, consistency management in the face of conflicting concurrent operations of the collaborators is a major challenge for its highly interconnected document structure among the computational modules - where any minor change in a part of the workflow can highly impact the other part of the collaborative workflow for the datalink relation among them. In addition to the consistency management, studies show several other challenges that need to be addressed towards a successful design of collaborative SWfMSs, such as sub-workflow composition and execution by different sub-groups, relationship between scientific workflows and collaboration models, sub-workflow monitoring, seamless integration and access control of the workflow components among collaborators and so on. In this thesis, we propose a locking scheme to facilitate consistency management in collaborative SWfMSs. The proposed method works by locking workflow components at a granular attribute level in addition to supporting locks on a targeted part of the collaborative workflow. We conducted several experiments to analyze the performance of the proposed method in comparison to related existing methods. Our studies show that the proposed method can reduce the average waiting time of a collaborator by up to 36% while increasing the average workflow update rate by up to 15% in comparison to existing descendent modular level locking techniques for collaborative SWfMSs. We also propose a role-based access control technique for the management of collaborative SWfMSs. We leverage the Collaborative Interactive Application Methodology (CIAM) for the investigation of role-based access control in the context of collaborative SWfMSs. We present our proposed method with a use-case of Plant Phenotyping and Genotyping research domain. Recent study shows that the collaborative SWfMSs often different sets of opportunities and challenges. From our investigations on existing research works towards collaborative SWfMSs and findings of our prior two studies, we propose an architecture of collaborative SWfMSs. We propose - SciWorCS - a Collaborative Scientific Workflow Management System as a proof of concept of the proposed architecture; which is the first of its kind to the best of our knowledge. We present several real-world use-cases of scientific workflows using SciWorCS. Finally, we conduct several user studies using SciWorCS comprising different real-world scientific workflows (i.e., from myExperiment) to understand the user behavior and styles of work in the context of collaborative SWfMSs. In addition to evaluating SciWorCS, the user studies reveal several interesting facts which can significantly contribute in the research domain, as none of the existing methods considered such empirical studies, and rather relied only on computer generated simulated studies for evaluation

Management of Long-Running High-Performance Persistent Object Stores

The popularity of object-oriented programming languages, such as Java and C++, for large application development has stirred an interest in improved technologies for high-performance, reliable, and scalable object storage. Such storage systems are typically referred to as Persistent Object Stores. This thesis describes the design and implementation of Sphere, a new persistent object store developed at the University of Glasgow, Scotland. The requirements for Sphere included high performance, support for transactional multi-threaded loads, scalability, extensibility, portability, reliability, referential integrity via the use of disk garbage collection, provision for flexible schema evolution, and minimised interaction with the mutator. The Sphere architecture is split into two parts: the core and the application-specific customisations. The core was designed to be modular, in order to encourage research and experimentation, and to be as light-weight as possible, in an attempt to achieve high performance through simplicity. The customisation part includes the code that deals with and is optimised for the specific load of the application that Sphere has to support: object formats, free-space management, etc. Even though specialising this part of the store is not trivial, it has the benefit that the interaction between the mutator and Sphere is direct and more efficient, as translation layers are not necessary. Major design decisions for Sphere included (i) splitting the store into partitions, to facilitate incremental disk garbage collection and schema evolution, (ii) using a flexible two-level free-space management, (Hi) introducing a three-dimensional method-dispatch matrix to invoke store operations, which contributes to Sphere's ease-of-extensibility, (iv) adopting a logical addressing scheme, to allow straightforward object and partition relocation, (v) requiring that Sphere can identify reference fields inside objects, so that it does not have to interact with the mutator in order to do so, and (vi) adopting the well-known ARIES recovery algorithm to ensure fault-tolerance. The thesis contains a detailed overview of Sphere and the context in which it was developed. Then, it concentrates on two areas that were explored using Sphere as the implementation platform. First, bulk object-loading issues are discussed and the Ghosted Allocation promotion algorithm is described. This algorithm was designed to allocate large numbers of objects to a store efficiently and with minimal log traffic and was evaluated using large-scale experiments. Second, the disk garbage collection framework of Sphere is overviewed and the implemented compacting, relocating garbage collector is described, along with the model of synchronisation with the mutator

PolyVR - A Virtual Reality Authoring Framework for Engineering Applications

Die virtuelle Realität ist ein fantastischer Ort, frei von Einschränkungen und vielen Möglichkeiten. Für Ingenieure ist dies der perfekte Ort, um Wissenschaft und Technik zu erleben, es fehlt jedoch die Infrastruktur, um die virtuelle Realität zugänglich zu machen, insbesondere für technische Anwendungen. Diese Arbeit bescheibt die Entstehung einer Softwareumgebung, die eine einfachere Entwicklung von Virtual-Reality-Anwendungen und deren Implementierung in immersiven Hardware-Setups ermöglicht. Virtual Engineering, die Verwendung virtueller Umgebungen für Design-Reviews während des Produktentwicklungsprozesses, wird insbesondere von kleinen und mittleren Unternehmen nur äußerst selten eingesetzt. Die Hauptgründe sind nicht mehr die hohen Kosten für professionelle Virtual-Reality-Hardware, sondern das Fehlen automatisierter Virtualisierungsabläufe und die hohen Wartungs- und Softwareentwicklungskosten. Ein wichtiger Aspekt bei der Automatisierung von Virtualisierung ist die Integration von Intelligenz in künstlichen Umgebungen. Ontologien sind die Grundlage des menschlichen Verstehens und der Intelligenz. Die Kategorisierung unseres Universums in Begriffe, Eigenschaften und Regeln ist ein grundlegender Schritt von Prozessen wie Beobachtung, Lernen oder Wissen. Diese Arbeit zielt darauf ab, einen Schritt zu einem breiteren Einsatz von Virtual-Reality-Anwendungen in allen Bereichen der Wissenschaft und Technik zu entwickeln. Der Ansatz ist der Aufbau eines Virtual-Reality-Authoring-Tools, eines Softwarepakets zur Vereinfachung der Erstellung von virtuellen Welten und der Implementierung dieser Welten in fortschrittlichen immersiven Hardware-Umgebungen wie verteilten Visualisierungssystemen. Ein weiteres Ziel dieser Arbeit ist es, das intuitive Authoring von semantischen Elementen in virtuellen Welten zu ermöglichen. Dies sollte die Erstellung von virtuellen Inhalten und die Interaktionsmöglichkeiten revolutionieren. Intelligente immersive Umgebungen sind der Schlüssel, um das Lernen und Trainieren in virtuellen Welten zu fördern, Prozesse zu planen und zu überwachen oder den Weg für völlig neue Interaktionsparadigmen zu ebnen

Generative Mesh Modeling

Generative Modeling is an alternative approach for the description of three-dimensional shape. The basic idea is to represent a model not as usual by an agglomeration of geometric primitives (triangles, point clouds, NURBS patches), but by functions. The paradigm change from objects to operations allows for a procedural representation of procedural shapes, such as most man-made objects. Instead of storing only the result of a 3D construction, the construction process itself is stored in a model file. The generative approach opens truly new perspectives in many ways, among others also for 3D knowledge management. It permits for instance to resort to a repository of already solved modeling problems, in order to re-use this knowledge also in different, slightly varied situations. The construction knowledge can be collected in digital libraries containing domain-specific parametric modeling tools. A concrete realization of this approach is a new general description language for 3D models, the "Generative Modeling Language" GML. As a Turing-complete "shape programming language" it is a basis of existing, primitv based 3D model formats. Together with its Runtime engine the GML permits - to store highly complex 3D models in a compact form, - to evaluate the description within fractions of a second, - to adaptively tesselate and to interactively display the model, - and even to change the models high-level parameters at runtime.Die generative Modellierung ist ein alternativer Ansatz zur Beschreibung von dreidimensionaler Form. Zugrunde liegt die Idee, ein Modell nicht wie üblich durch eine Ansammlung geometrischer Primitive (Dreiecke, Punkte, NURBS-Patches) zu beschreiben, sondern durch Funktionen. Der Paradigmenwechsel von Objekten zu Geometrie-erzeugenden Operationen ermöglicht es, prozedurale Modelle auch prozedural zu repräsentieren. Statt das Resultat eines 3D-Konstruktionsprozesses zu speichern, kann so der Konstruktionsprozess selber repräsentiert werden. Der generative Ansatz eröffnet unter anderem gänzlich neue Perspektiven für das Wissensmanagement im 3D-Bereich. Er ermöglicht etwa, auf einen Fundus bereits gelöster Konstruktions-Aufgaben zurückzugreifen, um sie in ähnlichen, aber leicht variierten Situationen wiederverwenden zu können. Das Konstruktions-Wissen kann dazu in Form von Bibliotheken parametrisierter, Domänen-spezifischer Modellier-Werkzeuge gesammelt werden. Konkret wird dazu eine neue allgemeine Modell-Beschreibungs-Sprache vorgeschlagen, die "Generative Modeling Language" GML. Als Turing-mächtige "Programmiersprache für Form" stellt sie eine echte Verallgemeinerung existierender Primitiv-basierter 3D-Modellformate dar. Zusammen mit ihrer Runtime-Engine erlaubt die GML, - hochkomplexe 3D-Objekte extrem kompakt zu beschreiben, - die Beschreibung innerhalb von Sekundenbruchteilen auszuwerten, - das Modell adaptiv darzustellen und interaktiv zu betrachten, - und die Modell-Parameter interaktiv zu verändern

IM-sgi an interface model for shape grammar implementations

This research arises from the interest in computing as offering new paradigms in the design practice. Information technologies are the driving force for progress in the processes of design, enabling new forms of creativity. The increasing sophistication of computer applications, their easier access, and lower cost have had a significant impact on design practices and can be regarded as a paradigm shift. The invention and creativity are thus seen as knowledge processing activities and can, at least partially, be carried out with the support of computer applications. In this context Shape Grammars (SG) as production systems of designs through rules have the potential to create designs with variable user input and the ability to evaluate a large number of alternatives that may lead to innovative designs. Most architects and designers use computers on their daily practice as a representation tool for their projects, but not as a facilitator or increaser of the creative process. SG computational implementations have the potential to enhance creativity with the test of a wide range of design options, helping the appearance of new solutions, either through the emergence of new shapes or by stimulating the designer’s creativity with the possibilities presented. As Architects and Designers haven't adopted existing SG computational implementations, that take advantage of computation to facilitate and enhance their work, could the problem be on the communication between the applications and the user? If the interface of the SG implementation does not allow the user to understand how to use it or how to control and make use of its results, it can’t be successfully used. With interest in SG implementations as creative partners in the creative process, our research starts with the analysis of existing SG implementations, trying to understand if they had the potential to be adopted by architects and designers in their practice and, if not, what could be done to lead to that objective. User Interface Inspection Methods were used to perform this analysis and allowed us to understand that there are interactions and communication issues that need to be addressed for SG implementations to be adopted by designers. Taking this direction, we understood that models of interaction between the user and SG implementations have already been developed. The present research proposal started from the analysis of the interaction model of Scott Chase, where he defines the different levels of interaction between the user and SG implementation, with more or less input from the user, establishing different ways to combine synergies to obtain new creative solutions. Taking this interaction model as a starting point, next, we must assure the correct communication between user and implementation occurs. The means of communication between these two agents is the computational interface. Understanding the importance of the interface to allow the user to know how to use the computational implementation and be able to produce results, our research presents the development of an interface model for SG implementations to help to take a step towards the adoption of SG for creative projects. For this, we used methods from Human-Computer Interaction discipline, and we also took Bastien & Scapin's "List of Ergonomic Criteria Guidelines" as guiding lines to define the Criteria of our interface model, called IM-sgi, Interface Model for Shape Grammar Implementations. Thus, IM-sgi, an interface model for SG Implementations, has the purpose of helping SG implementations developers to address the interface on the right path to a correct communication with the particular type of user that architects and designers are. Interface prototypes following IM-sgi criteria are finally developed and presented to test the suitability of the IM-sgi Model to SG implementations and validate the objectives we propose.A presente pesquisa surge do interesse na computação por oferecer novos paradigmas na prática do design. As tecnologias da informação são a força motriz para o progresso nos processos de design, permitindo novas formas de criatividade. A crescente sofisticação das aplicações computacionais, o acesso mais fácil às mesmas e menor custo associado tiveram um grande impacto nas práticas de projeto e podemos considerar estar perante uma mudança de paradigma. A invenção e a criatividade são, portanto, vistas como atividades de processamento de conhecimento e podem, pelo menos parcialmente, ser realizadas com o suporte do computador. Nesse contexto, As Gramáticas de Forma, como sistemas de produção de designs através de regras, têm o potencial de criar projetos com entradas com níveis variáveis de intervenção do utilizador e apresentam a capacidade de avaliar um grande número de alternativas que podem levar a designs inovadores. A maioria dos arquitetos e designers usa o computador na sua prática diária como uma ferramenta de representação para seus projetos, mas não como um facilitador ou potenciador do processo criativo. As implementações computacionais de Gramáticas de Forma têm o potencial de aumentar a criatividade com o teste de uma ampla gama de opções de design, ajudando no surgimento de novas soluções, seja pela emergência de novas formas ou estimulando a criatividade do designer com as opções desenvolvidas. Uma vez que as implementações computacionais de Gramáticas de Forma existentes não foram adotadas por Arquitetos e Designers, que claramente tiram proveito de aplicações computacionais para facilitar e aperfeiçoar o seu trabalho, poderá o problema estar na comunicação entre as implementações e o utilizador? Se a interface da implementação não permitir que o utilizador entenda como usá-la ou como controlar e utilizar os seus resultados, ela não poderá ser utilizada com sucesso. Com interesse nas implementações de Gramáticas de Forma como parceiros criativos no processo criativo, a nossa investigação começa com a análise das implementações de Gramáticas de Forma existentes, tentando entender se estas têm potencial para ser adotadas pelos criativos na sua prática e, se não, o que poderia ser feito para chegar a este objetivo. Foram usados métodos de inspeção para realizar esta análise para nos permitir compreender que há interações e problemas de comunicação que precisam de ser resolvidos para que as implementações de Gramáticas de Forma sejam adotadas pelos projetistas. Seguindo essa direção de investigação, percebemos que foram já desenvolvidos modelos de interação entre o utilizador e as implementações de Gramáticas de Forma. A presente proposta de pesquisa surgiu a partir da análise do modelo de interação de Scott Chase, onde este define os diferentes níveis de interação entre utilizador e implementação de Gramáticas de Forma, com maior ou menor input do utilizador, estabelecendo diferentes formas de combinar sinergias para obter novas soluções criativas. Tomando esse modelo de interação como ponto de partida, devemos assegurar que a comunicação correta entre o utilizador e a implementação ocorra. O meio de comunicação desses dois agentes é o interface computacional. Entendendo a importância do interface para permitir que o utilizador entenda como usar a implementação computacional e seja capaz de produzir resultados, a nossa pesquisa apresenta o desenvolvimento de um modelo de interface para implementações de Gramáticas de Forma para ajudar a dar um passo na direção da adoção das Gramáticas de Forma para projetos criativos. Deste modo, aplicámos métodos da disciplina de HCI e também adotámos a Lista de Diretrizes e Critérios Ergonómicos de Bastien & Scapin como linhas de orientação para definir os Critérios do nosso modelo de interface, denominado IM-sgi. O IM-sgi, um modelo de interface para Implementações de Gramática de Forma, tem a finalidade de ajudar programadores de implementações de Gramáticas de Forma a endereçar a interface no sentido de atingir uma comunicação correta com o tipo particular de utilizador que são os arquitetos e designers. Protótipos de interface seguindo os critérios IM-sgi são finalmente desenvolvidos e apresentados para testar a adequação do modelo IM-sgi e validar os objetivos que propomos

Atomic Transfer for Distributed Systems

Building applications and information systems increasingly means dealing with concurrency and faults stemming from distribution of system components. Atomic transactions are a well-known method for transferring the responsibility for handling concurrency and faults from developers to the software\u27s execution environment, but incur considerable execution overhead. This dissertation investigates methods that shift some of the burden of concurrency control into the network layer, to reduce response times and increase throughput. It anticipates future programmable network devices, enabling customized high-performance network protocols. We propose Atomic Transfer (AT), a distributed algorithm to prevent race conditions due to messages crossing on a path of network switches. Switches check request messages for conflicts with response messages traveling in the opposite direction. Conflicting requests are dropped, obviating the request\u27s receiving host from detecting and handling the conflict. AT is designed to perform well under high data contention, as concurrency control effort is balanced across a network instead of being handled by the contended endpoint hosts themselves. We use AT as the basis for a new optimistic transactional cache consistency algorithm, supporting execution of atomic applications caching shared data. We then present a scalable refinement, allowing hierarchical consistent caches with predictable performance despite high data update rates. We give detailed I/O Automata models of our algorithms along with correctness proofs. We begin with a simplified model, assuming static network paths and no message loss, and then refine it to support dynamic network paths and safe handling of message loss. We present a trie-based data structure for accelerating conflict-checking on switches, with benchmarks suggesting the feasibility of our approach from a performance stand-point