Web portals are considered “gateways” to the World Wide Web. These portals are becoming very popular entry points to the Web by offering important services such as email, news, weather reports, course notes and general information. In addition, some portal sites allow users the option of customising the site according to their personal interests. However, disabled and elderly people encounter many accessibility and usability barriers while accessing web portals. A preliminary review of a university portal was conducted to identify some of these accessibility problems. This treatise presents an overview of the processes to be followed when conducting an accessibility and usability evaluation. In addition, it mentions some guidelines to be considered when specifically designing portals for use by many different users from varying backgrounds.

This was a project to develop a Telephone Directory Web service (TDWS) to provide convenient and cost-effective access to public telephone directory data.

The primary purpose of this project is to develop an online forum to facilitate communication among educators, parents, and students resulting in an open environment for more informed decisions by all those involved in the educational process. The second purpose is the personal development of an electronic learning application using online tools needed for an effective online learning environment that will cost the school district little or nothing.

The World Wide Web is becoming a basic infrastructure for a variety of services, and the increases in audience size and client network bandwidth create service demands that are outpacing server capacity. Web clusters are one solution to this need for highperformance, highly available web server systems. We are interested in load distribution techniques, specifically Layer-7 algorithms that are content-aware. Layer- 7 algorithms allow distribution control based on the specific content requested, which is advantageous for a system that offers highly heterogenous services. We examine the performance of the Client Aware Policy (CAP) on a Linux/Apache web cluster consisting of a single web switch that directs requests to a pool of dual-processor SMP nodes. We show that the performance advantage of CAP over simple algorithms such as random and round-robin is as high as 29% on our testbed consisting of a mixture of static and dynamic content. Under heavily loaded conditions however, the performance decreases to the level of random distribution. In studying SMP vs. uniprocessor performance using the same number of processors with CAP distribution, we find that SMP dual-processor nodes under moderate workload levels provide equivalent throughput as the same number of CPU’s in a uniprocessor cluster. As workload increases to a heavily loaded state however, the SMP cluster shows reduced throughput compared to a cluster using uniprocessor nodes. We show that the web cluster’s maximum throughput increases linearly with the addition of more nodes to the server pool. We conclude that CAP is advantageous over random or round-robin distribution under certain conditions for highly dynamic workloads, and suggest some future enhancements that may improve its performance.

The way in which application systems and software are built has changed dramatically over the past few years. This is mainly due to advances in hardware technology, programming languages, as well as the requirement to build better software application systems in less time. The importance of mondial (worldwide) communication between systems is also growing exponentially. People are using network-based applications daily, communicating not only locally, but also globally. The Internet, the global network, therefore plays a significant role in the development of new software. Distributed object computing is one of the computing paradigms that promise to solve the need to develop clienVserver application systems, communicating over heterogeneous environments. This study, of limited scope, concentrates on one crucial element without which distributed object computing cannot be implemented. This element is the communication software, also called middleware, which allows objects situated on different hardware platforms to communicate over a network. Two of the most important middleware standards for distributed object computing today are the Common Object Request Broker Architecture (CORBA) from the Object Management Group, and the Distributed Component Object Model (DCOM) from Microsoft Corporation. Each of these standards is implemented in commercially available products, allowing distributed objects to communicate over heterogeneous networks. In studying each of the middleware standards, a formal way of comparing CORBA and DCOM is presented, namely meta-modelling. For each of these two distributed object infrastructures (middleware), meta-models are constructed. Based on this uniform and unbiased approach, a comparison of the two distributed object infrastructures is then performed. The results are given as a set of tables in which the differences and similarities of each distributed object infrastructure are exhibited. By adopting this approach, errors caused by misunderstanding or misinterpretation are minimised. Consequently, an accurate and unbiased comparison between CORBA and DCOM is made possible, which constitutes the main aim of this dissertation. / Computing / M. Sc. (Computer Science)

The number of Web traffic flows dominates Internet traffic today and most Web interactions are short-lived HTTP connections handled by TCP. Most core Internet routers use Drop Tail queuing which produces bursts of packet drops that contribute to unfair service. This thesis introduces two new active queue management (AQM) algorithms, PISA (PI with Short-lived flows Adjustment) and PIMC (PI with Minimum Cwnd). These AQMs are built on top of the PI (Proportional Integrator). To evaluate the performance of PISA and PIMC, a new simple model of HTTP traffic was developed for the NS-2 simulation. TCP sources inform PISA and PIMC routers of their congestion window by embedding a source hint in the packet header. Using the congestion window, PISA drops packets from short-lived Web flows less than packets from long-lived flows. Using a congestion window, PIMC does not drop a packet when congestion window is below a fixed threshold. This study provides a series of NS-2 experiments to investigate the behavior of PISA and PIMC. The results show fewer drops for both PISA and PIMC that avoids timeouts and increases the rate at which Web objects are sent. PISA and PIMC improve the performance of HTTP flows significantly over PI. PISA performs slightly better than PIMC.

The SOAP Service Description Language (SSDL) is a SOAP-centric language for describing Web Service contracts. SSDL focuses on message abstraction as the building block for creating service-oriented applications and provides an extensible range of protocol frameworks that can be used to describe and formally model Web Service interactions. SSDL's natural alignment with service-oriented design principles intuitively suggests that it encourages the creation of applications that adhere to this architectural paradigm. Given the lack of tools and empirical data for using SSDL as part of Web Services-based SOAs, we identified the need to investigate its practicability and usefulness through empirical work. To that end we have developed Soya, a programming model and runtime environment for creating and executing SSDL-based Web Services. On the one hand, Soya provides straightforward programming abstractions that foster message-oriented thinking. On the other hand, it leverages contemporary tooling (i.e. Windows Communication Foundation) with SSDL-related runtime functionality and semantics. In this thesis, we describe the design and architecture of Soya and show how it makes it possible to use SSDL as an alternative and powerful metadata language without imposing unrealistic burdens on application developers. In addition, we use Soya and SSDL in a case study which provides a set of initial empirical results with respect to SSDL's strengths and drawbacks. In summary, our work serves as a knowledge framework for better understanding message-oriented Web Service development and demonstrates SSDL's practicability in terms of implementation and usability.

The SOAP Service Description Language (SSDL) is a SOAP-centric language for describing Web Service contracts. SSDL focuses on message abstraction as the building block for creating service-oriented applications and provides an extensible range of protocol frameworks that can be used to describe and formally model Web Service interactions. SSDL's natural alignment with service-oriented design principles intuitively suggests that it encourages the creation of applications that adhere to this architectural paradigm. Given the lack of tools and empirical data for using SSDL as part of Web Services-based SOAs, we identified the need to investigate its practicability and usefulness through empirical work. To that end we have developed Soya, a programming model and runtime environment for creating and executing SSDL-based Web Services. On the one hand, Soya provides straightforward programming abstractions that foster message-oriented thinking. On the other hand, it leverages contemporary tooling (i.e. Windows Communication Foundation) with SSDL-related runtime functionality and semantics. In this thesis, we describe the design and architecture of Soya and show how it makes it possible to use SSDL as an alternative and powerful metadata language without imposing unrealistic burdens on application developers. In addition, we use Soya and SSDL in a case study which provides a set of initial empirical results with respect to SSDL's strengths and drawbacks. In summary, our work serves as a knowledge framework for better understanding message-oriented Web Service development and demonstrates SSDL's practicability in terms of implementation and usability.

The way in which application systems and software are built has changed dramatically over the past few years. This is mainly due to advances in hardware technology, programming languages, as well as the requirement to build better software application systems in less time. The importance of mondial (worldwide) communication between systems is also growing exponentially. People are using network-based applications daily, communicating not only locally, but also globally. The Internet, the global network, therefore plays a significant role in the development of new software. Distributed object computing is one of the computing paradigms that promise to solve the need to develop clienVserver application systems, communicating over heterogeneous environments. This study, of limited scope, concentrates on one crucial element without which distributed object computing cannot be implemented. This element is the communication software, also called middleware, which allows objects situated on different hardware platforms to communicate over a network. Two of the most important middleware standards for distributed object computing today are the Common Object Request Broker Architecture (CORBA) from the Object Management Group, and the Distributed Component Object Model (DCOM) from Microsoft Corporation. Each of these standards is implemented in commercially available products, allowing distributed objects to communicate over heterogeneous networks. In studying each of the middleware standards, a formal way of comparing CORBA and DCOM is presented, namely meta-modelling. For each of these two distributed object infrastructures (middleware), meta-models are constructed. Based on this uniform and unbiased approach, a comparison of the two distributed object infrastructures is then performed. The results are given as a set of tables in which the differences and similarities of each distributed object infrastructure are exhibited. By adopting this approach, errors caused by misunderstanding or misinterpretation are minimised. Consequently, an accurate and unbiased comparison between CORBA and DCOM is made possible, which constitutes the main aim of this dissertation. / Computing / M. Sc. (Computer Science)

This project simulates a real company by using Dreamweaver UltraDev, 4.0. A simulated electronic commerce web site was created to present all aspects of electronic commerce including future trends.