M.Sc. (Computer Science) / Information is a valuable resource in any organisation and more and more organisations are realising this and want efficient means to protect it against disclosure, modification or destruction. Although relatively efficient security methods have been available almost as long as information databases, they all provide additional cost. This cost does not only involve money but also cost in terms of system performance and management of information security. Any new information security model must also provide better management of information security. In this dissertation we present a model that provides information security and aims to lower the technical skills required to manage information security using this approach. In any business organisation we can describe each employee's duties. Put in other words, we can say that each employee has a specific business role in the organisation. In organisations with many employees there are typically many employees that have more or less the same duties in the organisation. This means that employees can be grouped according to their business roles. We use an employee's role as a description of his/her duties in a business organisation. ' Each role needs resources to perform its duties in the organisation. In terms of computer systems, each role needs computer resources such as printers. Most roles need access to data files in the organisation's database but it is not desirable to give all roles access to all data files. It is obvious that roles have specific privileges and restrictions in terms of information resources. Information security can be achieved by identifying the business roles in an organisation and giving these roles only the privileges needed to fulfill their business function and then assigning these roles to people (users of the organisation's computer system). This is called role-based security. People's business functions are related, for example clerks and clerk-managers are related in the sense that a clerk-manager is a manager of clerks. Business roles are related in the same way. For an information security manager to assign roles to users it is important to see this relationship between roles. In this dissertation we present this relationship using a lattice graph which we call a role lattice. The main advantage of this is that it is eases information security management...

The introduction of outcomes-based education (OBE) in South Africa has led to a new learner-centred approach with an emphasis on the outcomes that the learners need to achieve. With this learner-centred focus has come a greater need for record keeping. It is now necessary to track each learner’s progress towards the attainment of the learning outcomes. This progress is tracked in relation to assessment standards that are defined for every learning outcome. These assessment standards define the results expected of learners at certain stages in their development. The new OBE system has emphasised accountability and this is expressed in a requirement to keep evidence to justify the assessment results given. The large numbers of learners and the increased managerial demand of OBE cause problems to educators who may find themselves unable to keep track of the learners’ progress under such conditions. This dissertation investigates the structure of the new OBE system as well as its assessment and evidence requirements. From this the features required from a support system for educators in an OBE environment are determined. The supporting processes needed to enable these features to be implemented, as well as the storage requirements of such a system are identified. In addition to OBE, the field of Computer Integrated Learning Environments (CILEs) and Intelligent Tutoring Systems (ITSs) are investigated and useful details identified are added to the requirements for an OBE support system. The dissertation then presents an object-oriented conceptual model of the items that need to be stored in order to allow the features of an OBE support system to be implemented. The relationships between these items are also indicated in this model.

Because of an interest in object-oriented database systems, designers have created systems to store and manipulate specific sets of abstract data types that belong to the real world environment they represent. Unfortunately, the advantage of these systems is also a disadvantage since no single object-oriented database system can be used for all applications. This paper describes an object-oriented database management system called the Object-oriented Database Editor (ODE) which overcomes this disadvantage by allowing designers to create and execute an object-oriented database that represents any type of environment and then to store it and simulate that environment. As conditions within the environment change, the designer can use ODE to alter that environment without loss of data. ODE provides a flexible environment for the user; it is efficient; and it can run on a personal computer.

Object oriented databases have been gaining popularity over the years. Their ease of use and the advantages that they offer over relational databases have made them a popular choice amongst database administrators. Their use in previous years was restricted to business and administrative applications, but improvements in technology and the emergence of new, data-intensive applications has led to the increase in the use of object databases. This study investigates four Open Source object-oriented databases on their ability to carry out the standard database operations of storing, querying, updating and deleting database objects. Each of these databases will be timed in order to measure which is capable of performing a particular function faster than the other.

One of the most popular challenges facing academia and industry is the development of effective techniques and tools for maximizing the availability of data as the most valuable source of knowledge. The internet has dominated as the core for maximizing data availability and XML (eXtensible Markup Language) has emerged and is being gradually accepted as the universal standard format for platform independent publishing and exchanging data over the Internet. On the other hand, there remain large amount of data held in structured databases and database management systems have been traditionally used for the effective storage and manipulation of large volumes of data. This raised the need for effective methodologies capable of smoothly transforming data between different formats in general and between XML and structured databases in particular. This dissertation addresses the issue by proposing a two-way mapping approach between XML and object-oriented databases. The basic steps of the proposed approach are applied in a systematic way to produce a graph from the source and then transform the graph into the destination format. In other words, the derived graph summarizes characteristics of the source whether XML (elements and attributes) or object-oriented database (classes, inheritance and nesting hierarchies). Then, the developed methodology classifies nodes and links from the graph into the basic constructs of the destination, i.e., elements and attributes for XML or classes, inheritance and nesting hierarchies for object-oriented databases. The methodology has been successfully implemented and illustrative case studies are presented in this document.

This thesis describes the Graph Object Access Language (GOAL) and optimization techniques to execute GOAL statements. GOAL can be used to retrieve information stored in an object-oriented database system modeled as an information graph. It is an extension of the LEND query language developed by Chen et aI. The expressive power of GOAL and the effectiveness of the optimization techniques have been demonstrated using the WordNet database. Queries for the database have been identified and formulated using GOAL. The effectiveness of the optimization techniques has been demonstrated for six typical query forms with randomly selected words. / Master of Science

One of the most popular challenges facing academia and industry is the development of effective techniques and tools for maximizing the availability of data as the most valuable source of knowledge. The internet has dominated as the core for maximizing data availability and XML (eXtensible Markup Language) has emerged and is being gradually accepted as the universal standard format for platform independent publishing and exchanging data over the Internet. On the other hand, there remain large amount of data held in structured databases and database management systems have been traditionally used for the effective storage and manipulation of large volumes of data. This raised the need for effective methodologies capable of smoothly transforming data between different formats in general and between XML and structured databases in particular. This dissertation addresses the issue by proposing a two-way mapping approach between XML and object-oriented databases. The basic steps of the proposed approach are applied in a systematic way to produce a graph from the source and then transform the graph into the destination format. In other words, the derived graph summarizes characteristics of the source whether XML (elements and attributes) or object-oriented database (classes, inheritance and nesting hierarchies). Then, the developed methodology classifies nodes and links from the graph into the basic constructs of the destination, i.e., elements and attributes for XML or classes, inheritance and nesting hierarchies for object-oriented databases. The methodology has been successfully implemented and illustrative case studies are presented in this document.

O monitoramento de forma integrada pode se tornar complexo em ambientes com bancos de dados heterogêneos, devido às particularidades na sintaxe e em ferramentas disponíveis. Em particular, bancos de dados ativos permitem o desenvolvimento de mecanismos e a automação de processos que envolvam os dados ou objetos. Este trabalho propõe o desenvolvimento de uma arquitetura para identificar e monitorar eventos DDL (Data Definition Language), utilizando a abordagem de banco de dados ativos e recomendação. As aplicações desta arquitetura variam desde o simples monitoramento de eventos DDL em um ou mais bancos de dados, até a recomendação de possíveis configurações ou mudanças que podem ser realizadas no banco de dados monitorado. Neste contexto, essa dissertação propõe: (i) uma arquitetura integrada de banco de dados ativos e recomendação; (ii) a adaptação de um algoritmo de recomendação; e (iii) a validação dos conceitos aplicados através de um protótipo. / Integrated environments monitoring can become complex with heterogeneous databases, due to the particularities in the language syntax and available tools. In particular, active databases allow developing mechanisms and automation of processes involving data or objects. This work proposes the development of an architecture to identify and monitor DDL (Data Definition Language), exploring the active databases and recommendations approach. This architecture could be explored in several ways: simple monitoring of DDL events in one or more databases, or recommendation of future DDLs or settings within the monitored database. In this context, this work proposes: (i) an integrated architecture of active databases and recommendation; (ii) the adaptation of a recommendation algorithm; and (iii) the validation of concepts through a prototype.

The dissertation will outline an object-oriented model from which a next-generation GIS can be derived. The requirements for a spatial information analysis and modeling system can be broken into three primary functional classes: data management (data classification and access), analysis (modeling, optimization, and simulation) and visualization (display of data). These three functional classes can be considered as the primary colors of the spectrum from which the different shades of spatial analysis are composed. Object classes will be developed which will be designed to manipulate the three primary functions as required by the user and the data.

Modern data intensive applications, such as multimedia systems require the ability to store and manipulate complex data. The classical Database Management Systems (DBMS), such as relational databases, cannot support these types of applications efficiently. This dissertation presents the salient features of Object Database Management Systems (ODBMS) and Persistent Programming Languages (PPL), which have been developed to address the data management needs of these difficult applications. An 'impedance mismatch' problem occurs in the traditional DBMS because the data and computational aspects of the application are implemented using two different systems, that of query and programming language. PPL's provide facilities to cater for both persistent and transient data within the same language, hence avoiding the impedance mismatch problem. This dissertation presents a method of implementing a PPL by extending the language C++ with pre-compiled classes. The classes are first developed and then used to implement object persistence in two simple applications. / Computing / M. Sc. (Information Systems)