Geospatial Workflows and Trust: a Use Case for Provenance

At first glance the Astronomer by Vermeer, Tutankhamun’s burial mask, and a geospatial workflow may appear to have nothing in common. However, a commonality exists; each of these items can have a record of provenance detailing their history. Provenance is a record that shows who did what to an object, where this happened, and how and why these actions took place. In relation to the geospatial domain, provenance can be used to track and analyze the changes data has undergone in a workflow, and can facilitate scientific reproducibility. Collecting provenance from geospatial workflows and finding effective ways to use this provenance is an important application. When using geospatial data in a workflow it is important to determine if the data and workflow used are trustworthy. This study examines whether provenance can be collected from a geospatial workflow. Each workflow examined is a use case for a specific type of geospatial problem. In addition to this, the collected provenance is then used to determine workflow trust and content trust for each of the workflows examined in this study. The results of this study determined that provenance can be collected from a geospatial workflow in such a way as to be of use to additional applications, such as provenance interchange. From this collected provenance, content trust and workflow trust can be estimated. The simple workflow had a content trust value of .83 (trustworthy) and a workflow trust value of .44 (untrustworthy). Two additional workflows were examined for content trust and workflow trust. The methods used to calculate content trust and workflow trust could also be expanded to other types of geospatial data and workflows. Future research could include complete automation of the provenance collection and trust calculations, as well as examining additional techniques for deciding trust in relation to workflows

Web page performance analysis

Computer systems play an increasingly crucial and ubiquitous role in human endeavour by carrying out or facilitating tasks and providing information and services. How much work these systems can accomplish, within a certain amount of time, using a certain amount of resources, characterises the systems’ performance, which is a major concern when the systems are planned, designed, implemented, deployed, and evolve. As one of the most popular computer systems, the Web is inevitably scrutinised in terms of performance analysis that deals with its speed, capacity, resource utilisation, and availability. Performance analyses for the Web are normally done from the perspective of the Web servers and the underlying network (the Internet). This research, on the other hand, approaches Web performance analysis from the perspective of Web pages. The performance metric of interest here is response time. Response time is studied as an attribute of Web pages, instead of being considered purely a result of network and server conditions. A framework that consists of measurement, modelling, and monitoring (3Ms) of Web pages that revolves around response time is adopted to support the performance analysis activity. The measurement module enables Web page response time to be measured and is used to support the modelling module, which in turn provides references for the monitoring module. The monitoring module estimates response time. The three modules are used in the software development lifecycle to ensure that developed Web pages deliver at worst satisfactory response time (within a maximum acceptable time), or preferably much better response time, thereby maximising the efficiency of the pages. The framework proposes a systematic way to understand response time as it is related to specific characteristics of Web pages and explains how individual Web page response time can be examined and improved

Dynamic Reconfiguration with Virtual Services

We present a new architecture (virtual services) and accompanying implementation for dynamically adapting and reconfiguring the behavior of network services. Virtual services are a compositional middleware system that transparently interposes itself between a service and a client, overlaying new functionality with configurations of modules organized into processing chains. Virtual services allow programmers and system administrators to extend, modify, and reconfigure dynamically the behavior of existing services for which source code, object code, and administrative control are not available. Virtual service module processing chains are instantiated on a per connection or invocation basis, thereby enabling the reconfiguration of individual connections to a service without affecting other connections to the same service. To validate our architecture, we have implemented a virtual services software development toolkit and middleware server. Our experiments demonstrate that virtual services can modularize concerns that cut across network services. We show that we can reconfigure and enhance the security properties of services implemented as either TCP client-server systems, such as an HTTP server, or as remotely invocable objects, such as a Web service. We demonstrate that virtual services can reconfigure the following security properties and abilities: authentication, access control, secrecy/encryption, connection monitoring, security breach detection, adaptive response to security breaches, concurrent and dynamically mutable implementation of multiple security policies for different clients

Web service control of component-based agile manufacturing systems

Current global business competition has resulted in significant challenges for manufacturing and production sectors focused on shorter product lifecyc1es, more diverse and customized products as well as cost pressures from competitors and customers. To remain competitive, manufacturers, particularly in automotive industry, require the next generation of manufacturing paradigms supporting flexible and reconfigurable production systems that allow quick system changeovers for various types of products. In addition, closer integration of shop floor and business systems is required as indicated by the research efforts in investigating "Agile and Collaborative Manufacturing Systems" in supporting the production unit throughout the manufacturing lifecycles. The integration of a business enterprise with its shop-floor and lifecycle supply partners is currently only achieved through complex proprietary solutions due to differences in technology, particularly between automation and business systems. The situation is further complicated by the diverse types of automation control devices employed. Recently, the emerging technology of Service Oriented Architecture's (SOA's) and Web Services (WS) has been demonstrated and proved successful in linking business applications. The adoption of this Web Services approach at the automation level, that would enable a seamless integration of business enterprise and a shop-floor system, is an active research topic within the automotive domain. If successful, reconfigurable automation systems formed by a network of collaborative autonomous and open control platform in distributed, loosely coupled manufacturing environment can be realized through a unifying platform of WS interfaces for devices communication. The adoption of SOA- Web Services on embedded automation devices can be achieved employing Device Profile for Web Services (DPWS) protocols which encapsulate device control functionality as provided services (e.g. device I/O operation, device state notification, device discovery) and business application interfaces into physical control components of machining automation. This novel approach supports the possibility of integrating pervasive enterprise applications through unifying Web Services interfaces and neutral Simple Object Access Protocol (SOAP) message communication between control systems and business applications over standard Ethernet-Local Area Networks (LAN's). In addition, the re-configurability of the automation system is enhanced via the utilisation of Web Services throughout an automated control, build, installation, test, maintenance and reuse system lifecycle via device self-discovery provided by the DPWS protocol...cont'd

A Model for Scientific Workflows with Parallel and Distributed Computing

In the last decade we witnessed an immense evolution of the computing infrastructures in terms of processing, storage and communication. On one hand, developments in hardware architectures have made it possible to run multiple virtual machines on a single physical machine. On the other hand, the increase of the available network communication bandwidth has enabled the widespread use of distributed computing infrastructures, for example based on clusters, grids and clouds. The above factors enabled different scientific communities to aim for the development and implementation of complex scientific applications possibly involving large amounts of data. However, due to their structural complexity, these applications require decomposition models to allow multiple tasks running in parallel and distributed environments. The scientific workflow concept arises naturally as a way to model applications composed of multiple activities. In fact, in the past decades many initiatives have been undertaken to model application development using the workflow paradigm, both in the business and in scientific domains. However, despite such intensive efforts, current scientific workflow systems and tools still have limitations, which pose difficulties to the development of emerging large-scale, distributed and dynamic applications. This dissertation proposes the AWARD model for scientific workflows with parallel and distributed computing. AWARD is an acronym for Autonomic Workflow Activities Reconfigurable and Dynamic. The AWARD model has the following main characteristics. It is based on a decentralized execution control model where multiple autonomic workflow activities interact by exchanging tokens through input and output ports. The activities can be executed separately in diverse computing environments, such as in a single computer or on multiple virtual machines running on distributed infrastructures, such as clusters and clouds. It provides basic workflow patterns for parallel and distributed application decomposition and other useful patterns supporting feedback loops and load balancing. The model is suitable to express applications based on a finite or infinite number of iterations, thus allowing to model long-running workflows, which are typical in scientific experimention. A distintive contribution of the AWARD model is the support for dynamic reconfiguration of long-running workflows. A dynamic reconfiguration allows to modify the structure of the workflow, for example, to introduce new activities, modify the connections between activity input and output ports. The activity behavior can also be modified, for example, by dynamically replacing the activity algorithm. In addition to the proposal of a new workflow model, this dissertation presents the implementation of a fully functional software architecture that supports the AWARD model. The implemented prototype was used to validate and refine the model across multiple workflow scenarios whose usefulness has been demonstrated in practice clearly, through experimental results, demonstrating the advantages of the major characteristics and contributions of the AWARD model. The implemented prototype was also used to develop application cases, such as a workflow to support the implementation of the MapReduce model and a workflow to support a text mining application developed by an external user. The extensive experimental work confirmed the adequacy of the AWARD model and its implementation for developing applications that exploit parallelism and distribution using the scientific workflows paradigm

The lived experiences of black managers in accessing top management positions within the Namibian private corporate sector

This PhD study draws from anticolonial and decolonial thought systems to explore how multi-level factors; macro-level (social-contextual contextual histories, economic, legal and religious), meso-level (organisational cultures, structures, processes and procedures), and micro-level (interpersonal and intergroup), intersect to shape the experiences of black managers in accessing top management positions within Namibian private sector organisations. This study aimed to uncover the historical and political elements that underpin black managers' experiences. The data in this study was collected through a decolonial data collection process utilizing storytelling interviews with 44 study participants, recruited through snowball sampling. The research adopts a qualitative research design that infuses thematic analysis with decolonial, and anticolonial, lenses of data analyses, rooted in the African indigenous paradigm. The findings of this study reveal influential multi-level factors influencing the experiences of black managers are interwoven and imbued with coloniality of power (coloniality)—continuing colonial social and economic patterns rooted in the colonial histories that are not lost to the past. In the Namibian context, coloniality is anchored in the histories of colonial violence, including the German genocide of black Namibians (1904-1908) and its apartheid successor. These histories continue to reside in the society and the private sector, re-inscribing and entrenching colonial social and economic relations that are (re)produced at organisational levels. The study's critical theoretical contribution highlights coloniality as the deep-seated and concealed structure undergirding the persistent racial inequalities within Namibian private sector organisations, through which black managers are subjugated, disempowered, exploited, and marginalised from opportunities to access organisational resources and top management positions. Furthermore, the study shows that coloniality in the contemporary private sector is intimately tied to the private sector's participation in past colonial violence. At present, it appears that coloniality in the private sector is facilitated by influential white executives forming white affiliations of power in maintaining the material and symbolic interests of the white minority populace. This study labels these enacted implicit political and insidious managerial practices and mechanisms as: 'managing to colonise'. Finally, this study recommends dismantling the coloniality of power underlying racial inequalities in the private sector and the broader Namibian society through anticolonial and decolonial praxis grounded in reparative social justice, equality and self-determination