No description available.

No description available.

No description available.

The Java Devlopment Environment defines SQLJ as a standard way of embedding the relational database language SQL in the object-oriented programming language Java. Oracle Corporation provides an extension of SQLJ that supports dynamic SQL constructs for the processing of SQL commands that are not completely known at compile time. Unfortunately, these constructs are not sufficient to handle all dynamic situations, so that the programmer has to depend on other SQL embeddings, such as JDBC, in addition to Oracle's SQLJ. In this thesis we implement several extensions to Oracle's SQLJ so that all dynamic situations can be programmed in SQLJ, without resorting to other SQL embeddings. We also add a sub-query based for loop facility, similar to the one provided in Oracle's database programming language PL/SQL, as an improvement over the iterator constructs that SQLJ provides. This thesis discusses the design, development and implementation of these SQLJ extensions, and provided applications that show the utility of these extensions in terms of clarity and power. / by Louis M. Bradley. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

We consider a class of queueing systems that consist of server pools in parallel and multiple customer classes. Customer service times are assumed to be exponentially distributed. We study the asymptotic behavior of these queueing systems in a heavy traffic regime that is known as the Halfin and Whitt many-server asymptotic regime. Our main contribution is a general framework for establishing state space collapse results in the Halfin and Whitt many-server asymptotic regime for parallel server systems having multiple customer classes. In our work, state space collapse refers to a decrease in the dimension of the processes tracking the number of customers in each class waiting for service and the number of customers in each class being served by various server pools. We define and introduce a state space collapse function, which governs the exact details of the state space collapse. Our methodology is similar in spirit to that in Bramson (1998); however, Bramson studies an asymptotic regime in which the number of servers is fixed and Bramson does not require a state space collapse function. We illustrate the applications of our results in three different parallel server systems. The first system is a distributed parallel server system under the minimum-expected-delay faster-server-first (MED-FSF) or minimumexpected- delay load-balancing (MED-LB) policies. We prove that the MED-FSF policy minimizes the stationary distribution of total number of customers in the system. However, under the MED-FSF policy all the servers in our distributed system except those with the lowest service rate experience 100% utilization but under the MED-LB policy, on the other hand, the utilizations of all the server pools are equal. The second system we consider is known as the N-model. We show that when the service times only depend on the server pool providing service a static priority rule is asymptotically optimal. Finally, we study two results conjectured in the literature for V-systems. We show for all of these systems that the conditions on the hydrodynamic limits can easily be checked using the standard tools that have been developed in the literature to analyze fluid models.

Submitted in fulfillment of the academic requirements for the degree of Doctor of Philosophy in Information Technology, Durban University of Technology, Durban, South Africa, 2016. / Motivated by the literature regarding the need for further research on client participation in software development, a systemic framework for the understanding of client requirements in Information System development projects is developed. This systemic framework is particularly relevant for project contexts characterized by diversity of stakeholder values and complexity. To address this complexity, research led to the selection of methods from three systems methodologies and the conclusion for the need to mix them in the process of requirements understanding by clients. The mixing of methods from various methodologies is justified through the principles of Critical Systems Practice, and the process of their use is guided by Action Design Research. In spite of the strong research tradition associated with Soft Systems Methodology and the growing interest in the Work System Method, the level of use of these by practitioners is not high because complex project situations require harnessing of the strengths of more than one methodology. The proposed framework also includes a third system methodology Critical Systems Heuristics. This study demonstrated how the meta-methodology Critical Systems Practice is applied in justifying the selection and the mix of methods from the above three methodologies in the proposed framework. The principles of design science were applied, where the framework is the design artifact that is developed. Action Research was used to guide evaluation of the framework in the pilot study. The framework was applied in a pilot study to the understanding of the management of a Wellness Centre which operates within the Kenneth Gardens Housing Estate, through action research. As a result of the pilot study some modifications were made to the framework and the process of its implementation. The modified framework was applied in a further main study concerning the management of the Kenneth Gardens Housing Estate which has a broader context than the pilot study. The contribution of this research to the field of Information Systems is both theoretical and practical. One theoretical contribution is provision of a framework for clearer understanding of software requirements by clients. The second theoretical contribution is that Action Design Research is enhanced by adding proper justification for the methods included in the framework through the application of Critical Systems Thinking and Critical Systems Practice. The practical contribution is through the demonstration of Action Design Research being applied to a real-world problem in both the pilot and the main study. / D

Applications that use directory services or relational databases operate in client-server mode where a client requests information from a server, and the server returns a response to the client. Communication between each client-server application is achieved by using separate custom built front-ends with non-portable data formats. A need exists to access information from different heterogeneous client-server systems in a standard message request-response format. This research proposes a generic XML document that presents a common request-response interface to the client from which they can access network protocol or database information. The XML component is easily adaptable to accessing any new client-server type protocol or database data that may be added to a server. The approach in determining the XML elements is, firstly review each systems command and data structure separately, and then determine if there are any commonalities within each protocol that would allow for a common representation of both the data and command structure. For the purposes of this project, three different data sources that are typically used in an Internet application were analysed, namely: -- a TCP based server program; -- a relational type database; and -- a directory service. The solution was implemented using Linux as the operating system, Java as the programming language, MySQL as the relational database, openLDAP as the directory server and a proprietary TCP based server application. Initially the complete system was developed for the proprietary TCP-based application. The other systems were added with minimum additional work. The result of the implementation was that it is relatively easy to add new protocols (for e.g. LDAP) on an as needed basis with minimal changes required on the server side. A client will receive XML responses that the client can either adapt (typically using a separate style-sheet) to their specific needs or use the existing front-ends if they are suitable. After the design was implemented and tested, the performance of XML and non-XML messages was evaluated. As expected the increased verbosity of XML results in a larger footprint that requires more processing time and resources. This means that any implementation using XML has to carefully weight the benefits of flexibility, extensibility and standard message formats against reduced performance. After evaluating XML type messages in an Internet type environment that involved human-computer interaction, it was concluded that the slower response times is not that significant to negate the benefits of a common message interface provided by using XML. / Dissertation (M Eng (Computer Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

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 purpose of this project is to develop a generic Java Application Programming Interface (API) that would be used to provide security and user privacy to functions such as data transfer, key management, digital signature, etc.

In today's highly competitive global economy, information resources representing enterprise-wide information are essential to the survival of an organization. The development of and increase in the use of personal computers and data communication networks are supporting or, in many cases, replacing the traditional computer mainstay of corporations. The client/server model incorporates mainframe programming with desktop applications on personal computers. The aim of the research is to compile a technology model for the development of client/server software. A comprehensive overview of the individual components of the client/server system is given. The different methodologies, tools and techniques that can be used are reviewed, as well as client/server-specific design issues. The research is intended to create a road map in the form of a Technology Reference Model for Client/Server Software Development. / Computing / M. Sc. (Information Systems)