A detailed investigation of interoperability for web services
- Authors: Wright, Madeleine
- Date: 2006
- Subjects: Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4592 , http://hdl.handle.net/10962/d1004832 , Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Description: The thesis presents a qualitative survey of web services' interoperability, offering a snapshot of development and trends at the end of 2005. It starts by examining the beginnings of web services in earlier distributed computing and middleware technologies, determining the distance from these approaches evident in current web-services architectures. It establishes a working definition of web services, examining the protocols that now seek to define it and the extent to which they contribute to its most crucial feature, interoperability. The thesis then considers the REST approach to web services as being in a class of its own, concluding that this approach to interoperable distributed computing is not only the simplest but also the most interoperable. It looks briefly at interoperability issues raised by technologies in the wider arena of Service Oriented Architecture. The chapter on protocols is complemented by a chapter that validates the qualitative findings by examining web services in practice. These have been implemented by a variety of toolkits and on different platforms. Included in the study is a preliminary examination of JAX-WS, the replacement for JAX-RPC, which is still under development. Although the main language of implementation is Java, the study includes services in C# and PHP and one implementation of a client using a Firefox extension. The study concludes that different forms of web service may co-exist with earlier middleware technologies. While remaining aware that there are still pitfalls that might yet derail the movement towards greater interoperability, the conclusion sounds an optimistic note that recent cooperation between different vendors may yet result in a solution that achieves interoperability through core web-service standards.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Madeleine
- Date: 2006
- Subjects: Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4592 , http://hdl.handle.net/10962/d1004832 , Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Description: The thesis presents a qualitative survey of web services' interoperability, offering a snapshot of development and trends at the end of 2005. It starts by examining the beginnings of web services in earlier distributed computing and middleware technologies, determining the distance from these approaches evident in current web-services architectures. It establishes a working definition of web services, examining the protocols that now seek to define it and the extent to which they contribute to its most crucial feature, interoperability. The thesis then considers the REST approach to web services as being in a class of its own, concluding that this approach to interoperable distributed computing is not only the simplest but also the most interoperable. It looks briefly at interoperability issues raised by technologies in the wider arena of Service Oriented Architecture. The chapter on protocols is complemented by a chapter that validates the qualitative findings by examining web services in practice. These have been implemented by a variety of toolkits and on different platforms. Included in the study is a preliminary examination of JAX-WS, the replacement for JAX-RPC, which is still under development. Although the main language of implementation is Java, the study includes services in C# and PHP and one implementation of a client using a Firefox extension. The study concludes that different forms of web service may co-exist with earlier middleware technologies. While remaining aware that there are still pitfalls that might yet derail the movement towards greater interoperability, the conclusion sounds an optimistic note that recent cooperation between different vendors may yet result in a solution that achieves interoperability through core web-service standards.
- Full Text:
- Date Issued: 2006
An investigation into some critical computer networking parameters : Internet addressing and routing
- Authors: Isted, Edwin David
- Date: 1996
- Subjects: Computer networks , Internet , Electronic mail systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4608 , http://hdl.handle.net/10962/d1004874 , Computer networks , Internet , Electronic mail systems
- Description: This thesis describes the evaluation of several proposals suggested as replacements for the currenT Internet's TCPJIP protocol suite. The emphasis of this thesis is on how the proposals solve the current routing and addressing problems associated with the Internet. The addressing problem is found to be related to address space depletion, and the routing problem related to excessive routing costs. The evaluation is performed based on criteria selected for their applicability as future Internet design criteria. AIl the protocols are evaluated using the above-mentioned criteria. It is concluded that the most suitable addressing mechanism is an expandable multi-level format, with a logical separation of location and host identification information. Similarly, the most suitable network representation technique is found to be an unrestricted hierarchical structure which uses a suitable abstraction mechanism. It is further found that these two solutions could adequately solve the existing addressing and routing problems and allow substantial growth of the Internet.
- Full Text:
- Date Issued: 1996
An investigation into some critical computer networking parameters : Internet addressing and routing
- Authors: Isted, Edwin David
- Date: 1996
- Subjects: Computer networks , Internet , Electronic mail systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4608 , http://hdl.handle.net/10962/d1004874 , Computer networks , Internet , Electronic mail systems
- Description: This thesis describes the evaluation of several proposals suggested as replacements for the currenT Internet's TCPJIP protocol suite. The emphasis of this thesis is on how the proposals solve the current routing and addressing problems associated with the Internet. The addressing problem is found to be related to address space depletion, and the routing problem related to excessive routing costs. The evaluation is performed based on criteria selected for their applicability as future Internet design criteria. AIl the protocols are evaluated using the above-mentioned criteria. It is concluded that the most suitable addressing mechanism is an expandable multi-level format, with a logical separation of location and host identification information. Similarly, the most suitable network representation technique is found to be an unrestricted hierarchical structure which uses a suitable abstraction mechanism. It is further found that these two solutions could adequately solve the existing addressing and routing problems and allow substantial growth of the Internet.
- Full Text:
- Date Issued: 1996
Investigating the viability of a framework for small scale, easily deployable and extensible hotspot management systems
- Authors: Thinyane, Mamello P
- Date: 2006
- Subjects: Local area networks (Computer networks) , Computer networks -- Management , Computer network architectures , Computer network protocols , Wireless communication systems , XML (Document markup language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4638 , http://hdl.handle.net/10962/d1006553
- Description: The proliferation of PALs (Public Access Locations) is fuelling the development of new standards, protocols, services, and applications for WLANs (Wireless Local Area Networks). PALs are set up at public locations to meet continually changing, multiservice, multi-protocol user requirements. This research investigates the essential infrastructural requirements that will enable further proliferation of PALs, and consequently facilitate ubiquitous computing. Based on these requirements, an extensible architectural framework for PAL management systems that inherently facilitates the provisioning of multiple services and multiple protocols on PALs is derived. The ensuing framework, which is called Xobogel, is based on the microkernel architectural pattern, and the IPDR (Internet Protocol Data Record) specification. Xobogel takes into consideration and supports the implementation of diverse business models for PALs, in respect of distinct environmental factors. It also facilitates next-generation network service usage accounting through a simple, flexible, and extensible XML based usage record. The framework is subsequently validated for service element extensibility and simplicity through the design, implementation, and experimental deployment of SEHS (Small Extensible Hotspot System), a system based on the framework. The robustness and scalability of the framework is observed to be sufficient for SMME deployment, withstanding the stress testing experiments performed on SEHS. The range of service element and charging modules implemented confirm an acceptable level of flexibility and extensibility within the framework.
- Full Text:
- Date Issued: 2006
- Authors: Thinyane, Mamello P
- Date: 2006
- Subjects: Local area networks (Computer networks) , Computer networks -- Management , Computer network architectures , Computer network protocols , Wireless communication systems , XML (Document markup language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4638 , http://hdl.handle.net/10962/d1006553
- Description: The proliferation of PALs (Public Access Locations) is fuelling the development of new standards, protocols, services, and applications for WLANs (Wireless Local Area Networks). PALs are set up at public locations to meet continually changing, multiservice, multi-protocol user requirements. This research investigates the essential infrastructural requirements that will enable further proliferation of PALs, and consequently facilitate ubiquitous computing. Based on these requirements, an extensible architectural framework for PAL management systems that inherently facilitates the provisioning of multiple services and multiple protocols on PALs is derived. The ensuing framework, which is called Xobogel, is based on the microkernel architectural pattern, and the IPDR (Internet Protocol Data Record) specification. Xobogel takes into consideration and supports the implementation of diverse business models for PALs, in respect of distinct environmental factors. It also facilitates next-generation network service usage accounting through a simple, flexible, and extensible XML based usage record. The framework is subsequently validated for service element extensibility and simplicity through the design, implementation, and experimental deployment of SEHS (Small Extensible Hotspot System), a system based on the framework. The robustness and scalability of the framework is observed to be sufficient for SMME deployment, withstanding the stress testing experiments performed on SEHS. The range of service element and charging modules implemented confirm an acceptable level of flexibility and extensibility within the framework.
- Full Text:
- Date Issued: 2006
An investigation into the viability of deploying thin client technology to support effective learning in a disadvantaged, rural high school setting
- Authors: Ndwe, Tembalethu Jama
- Date: 2002
- Subjects: Network computers , Education -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4627 , http://hdl.handle.net/10962/d1006500 , Network computers , Education -- Data processing
- Description: Computer Based Training offers many attractive learning opportunities for high school pupils. Its deployment in economically depressed and educationally marginalized rural schools is extremely uncommon due to the high technology skills and costs involved in its deployment and ongoing maintenance. This thesis puts forward thin client technology as a potential solution to the needs of education environments of this kind. A functional business case is developed and evaluated in this thesis, based upon a requirements analysis of media delivery in learning, and upon formal cost/performance models and a deployment field trial. Because of the economic constraints of the envisaged deployment area in rural education, an industrial field trial is used, and the aspects of this trial that can be carried over to the rural school situation have been used to assess performance and cost indicators. Our study finds that thin client technology could be deployed and maintained more cost effectively than conventional fat client solutions in rural schools, that it is capable of supporting the learning elements needed in this deployment area, and that it is able to deliver the predominantly text based applications currently being used in schools. However, we find that technological improvements are needed before future multimediaintensive applications can be adequately supported.
- Full Text:
- Date Issued: 2002
- Authors: Ndwe, Tembalethu Jama
- Date: 2002
- Subjects: Network computers , Education -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4627 , http://hdl.handle.net/10962/d1006500 , Network computers , Education -- Data processing
- Description: Computer Based Training offers many attractive learning opportunities for high school pupils. Its deployment in economically depressed and educationally marginalized rural schools is extremely uncommon due to the high technology skills and costs involved in its deployment and ongoing maintenance. This thesis puts forward thin client technology as a potential solution to the needs of education environments of this kind. A functional business case is developed and evaluated in this thesis, based upon a requirements analysis of media delivery in learning, and upon formal cost/performance models and a deployment field trial. Because of the economic constraints of the envisaged deployment area in rural education, an industrial field trial is used, and the aspects of this trial that can be carried over to the rural school situation have been used to assess performance and cost indicators. Our study finds that thin client technology could be deployed and maintained more cost effectively than conventional fat client solutions in rural schools, that it is capable of supporting the learning elements needed in this deployment area, and that it is able to deliver the predominantly text based applications currently being used in schools. However, we find that technological improvements are needed before future multimediaintensive applications can be adequately supported.
- Full Text:
- Date Issued: 2002
Analyzing communication flow and process placement in Linda programs on transputers
- De-Heer-Menlah, Frederick Kofi
- Authors: De-Heer-Menlah, Frederick Kofi
- Date: 1992 , 2012-11-28
- Subjects: LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4675 , http://hdl.handle.net/10962/d1006698 , LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Description: With the evolution of parallel and distributed systems, users from diverse disciplines have looked to these systems as a solution to their ever increasing needs for computer processing resources. Because parallel processing systems currently require a high level of expertise to program, many researchers are investing effort into developing programming approaches which hide some of the difficulties of parallel programming from users. Linda, is one such parallel paradigm, which is intuitive to use, and which provides a high level decoupling between distributable components of parallel programs. In Linda, efficiency becomes a concern of the implementation rather than of the programmer. There is a substantial overhead in implementing Linda, an inherently shared memory model on a distributed system. This thesis describes the compile-time analysis of tuple space interactions which reduce the run-time matching costs, and permits the distributon of the tuple space data. A language independent module which partitions the tuple space data and suggests appropriate storage schemes for the partitions so as to optimise Linda operations is presented. The thesis also discusses hiding the network topology from the user by automatically allocating Linda processes and tuple space partitons to nodes in the network of transputers. This is done by introducing a fast placement algorithm developed for Linda. , KMBT_223
- Full Text:
- Date Issued: 1992
- Authors: De-Heer-Menlah, Frederick Kofi
- Date: 1992 , 2012-11-28
- Subjects: LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4675 , http://hdl.handle.net/10962/d1006698 , LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Description: With the evolution of parallel and distributed systems, users from diverse disciplines have looked to these systems as a solution to their ever increasing needs for computer processing resources. Because parallel processing systems currently require a high level of expertise to program, many researchers are investing effort into developing programming approaches which hide some of the difficulties of parallel programming from users. Linda, is one such parallel paradigm, which is intuitive to use, and which provides a high level decoupling between distributable components of parallel programs. In Linda, efficiency becomes a concern of the implementation rather than of the programmer. There is a substantial overhead in implementing Linda, an inherently shared memory model on a distributed system. This thesis describes the compile-time analysis of tuple space interactions which reduce the run-time matching costs, and permits the distributon of the tuple space data. A language independent module which partitions the tuple space data and suggests appropriate storage schemes for the partitions so as to optimise Linda operations is presented. The thesis also discusses hiding the network topology from the user by automatically allocating Linda processes and tuple space partitons to nodes in the network of transputers. This is done by introducing a fast placement algorithm developed for Linda. , KMBT_223
- Full Text:
- Date Issued: 1992
Initial findings of an investigation into the feasibility of a low level image processing workstation using transputers
- Authors: Cooke, Nicholas Duncan
- Date: 1990 , 2013-02-07
- Subjects: Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4679 , http://hdl.handle.net/10962/d1006702 , Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Description: From Introduction: The research concentrates primarily on a feasibility study involving the setting up of an image processing workstation. As broad as this statement concerning the workstation may seem, there are several factors limiting the extent of the research. This project is not concerned with the design and implementation of a fully-fledged image processing workstation. Rather, it concerns an initial feasibility study of such a workstation, centered on the theme image processing aided by the parallel processing paradigm. In looking at the hardware available for the project, in the context of an image processing environment, a large amount of initial investigation was required prior to that concerned with the transputer and parallel processing. Work was done on the capturing and displaying of images. This formed a vital part of the project. Furthermore, considering that a new architecture was being used as the work horse within a conventional host architecture, the INTEL 80286, several aspects of the host architecture had also to be investigated. These included the actual processing capabilities of the host, the capturing and storing of the images on the host, and most importantly, the interface between the host and the transputer [C0089]. Benchmarking was important in order for good conclusions to be drawn about the viability of the two types of hardware used, both individually and together. On the subject of the transputer as the workhorse, there were several areas whlch required investigation. Initial work had to cover the choice of network topology on whlch the benchmarking of some of the image processing applications were performed. Research into this was based on the previous work of several authors, whlch introduced features relevant to this investigation. The network used for this investigation was chosen to be generally applicable to a broad spectrum of applications in image processing. It was not chosen for its applicability for a single dedicated application, as has been the case for much of the past research performed in image processing [SAN88] [SCH89]. The concept of image processing techniques being implemented on the transputer required careful consideration in respect of what should be implemented. Image processing is not a new subject, and it encompasses a large spectrum of applications. The transputer, with image processing being hlghly suited to it, has attracted a good deal of research. It would not be rash to say that the easy research was covered first. The more trivial operations in image processing, requiring matrix type operations on the pixels attracted, the most coverage. Several researchers in the field of image processing on the transputer have broken the back of this set of problems. Conclusions regarding these operations on the transputer returned a fairly standard answer. An area of image processing which has not produced the same volume of return as that concerning the more trivial operations, is the subject of Fourier Analysis, that is, the Fourier Transform. Thus a major part of this project concerns an investigation into the Fourier Transform in image processing, in particular the Fast Fourier Transform. The network chosen for thls research has placed some constraint upon the degree of parallelism that can be achleved. It should be emphasized that this project is not concerned with the most efficient implementation of a specific image processing algorithm on a dedicated topology. Rather, it looks at the feasibility of a general system in the domain of image processing, concerned with a hlghly computationally intensive operation. This has had the effect of testing the processing power of the hardware used, and contributing a widely applicable parallel algorithm for use in Fourier Analysis. 3 These are discussed more fully in Chapter 2, which covers the work related to tbis project. The results of the investigation are presented along with a discussion of the methods throughout the thesis. The final chapter summarizes the findings of the research, assesses the value of the investigation, and points out areas for future investigation.
- Full Text:
- Date Issued: 1990
- Authors: Cooke, Nicholas Duncan
- Date: 1990 , 2013-02-07
- Subjects: Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4679 , http://hdl.handle.net/10962/d1006702 , Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Description: From Introduction: The research concentrates primarily on a feasibility study involving the setting up of an image processing workstation. As broad as this statement concerning the workstation may seem, there are several factors limiting the extent of the research. This project is not concerned with the design and implementation of a fully-fledged image processing workstation. Rather, it concerns an initial feasibility study of such a workstation, centered on the theme image processing aided by the parallel processing paradigm. In looking at the hardware available for the project, in the context of an image processing environment, a large amount of initial investigation was required prior to that concerned with the transputer and parallel processing. Work was done on the capturing and displaying of images. This formed a vital part of the project. Furthermore, considering that a new architecture was being used as the work horse within a conventional host architecture, the INTEL 80286, several aspects of the host architecture had also to be investigated. These included the actual processing capabilities of the host, the capturing and storing of the images on the host, and most importantly, the interface between the host and the transputer [C0089]. Benchmarking was important in order for good conclusions to be drawn about the viability of the two types of hardware used, both individually and together. On the subject of the transputer as the workhorse, there were several areas whlch required investigation. Initial work had to cover the choice of network topology on whlch the benchmarking of some of the image processing applications were performed. Research into this was based on the previous work of several authors, whlch introduced features relevant to this investigation. The network used for this investigation was chosen to be generally applicable to a broad spectrum of applications in image processing. It was not chosen for its applicability for a single dedicated application, as has been the case for much of the past research performed in image processing [SAN88] [SCH89]. The concept of image processing techniques being implemented on the transputer required careful consideration in respect of what should be implemented. Image processing is not a new subject, and it encompasses a large spectrum of applications. The transputer, with image processing being hlghly suited to it, has attracted a good deal of research. It would not be rash to say that the easy research was covered first. The more trivial operations in image processing, requiring matrix type operations on the pixels attracted, the most coverage. Several researchers in the field of image processing on the transputer have broken the back of this set of problems. Conclusions regarding these operations on the transputer returned a fairly standard answer. An area of image processing which has not produced the same volume of return as that concerning the more trivial operations, is the subject of Fourier Analysis, that is, the Fourier Transform. Thus a major part of this project concerns an investigation into the Fourier Transform in image processing, in particular the Fast Fourier Transform. The network chosen for thls research has placed some constraint upon the degree of parallelism that can be achleved. It should be emphasized that this project is not concerned with the most efficient implementation of a specific image processing algorithm on a dedicated topology. Rather, it looks at the feasibility of a general system in the domain of image processing, concerned with a hlghly computationally intensive operation. This has had the effect of testing the processing power of the hardware used, and contributing a widely applicable parallel algorithm for use in Fourier Analysis. 3 These are discussed more fully in Chapter 2, which covers the work related to tbis project. The results of the investigation are presented along with a discussion of the methods throughout the thesis. The final chapter summarizes the findings of the research, assesses the value of the investigation, and points out areas for future investigation.
- Full Text:
- Date Issued: 1990
Cogitator : a parallel, fuzzy, database-driven expert system
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
CREWS : a Component-driven, Run-time Extensible Web Service framework
- Authors: Parry, Dominic Charles
- Date: 2004
- Subjects: Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4628 , http://hdl.handle.net/10962/d1006501 , Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Description: There has been an increased focus in recent years on the development of re-usable software, in the form of objects and software components. This increase, together with pressures from enterprises conducting transactions on the Web to support all business interactions on all scales, has encouraged research towards the development of easily reconfigurable and highly adaptable Web services. This work investigates the ability of Component-Based Software Development (CBSD) to produce such systems, and proposes a more manageable use of CBSD methodologies. Component-Driven Software Development (CDSD) is introduced to enable better component manageability. Current Web service technologies are also examined to determine their ability to support extensible Web services, and a dynamic Web service architecture is proposed. The work also describes the development of two proof-of-concept systems, DREW Chat and Hamilton Bank. DREW Chat and Hamilton Bank are implementations of Web services that support extension dynamically and at run-time. DREW Chat is implemented on the client side, where the user is given the ability to change the client as required. Hamilton Bank is a server-side implementation, which is run-time customisable by both the user and the party offering the service. In each case, a generic architecture is produced to support dynamic Web services. These architectures are combined to produce CREWS, a Component-driven Runtime Extensible Web Service solution that enables Web services to support the ever changing needs of enterprises. A discussion of similar work is presented, identifying the strengths and weaknesses of our architecture when compared to other solutions.
- Full Text:
- Date Issued: 2004
- Authors: Parry, Dominic Charles
- Date: 2004
- Subjects: Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4628 , http://hdl.handle.net/10962/d1006501 , Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Description: There has been an increased focus in recent years on the development of re-usable software, in the form of objects and software components. This increase, together with pressures from enterprises conducting transactions on the Web to support all business interactions on all scales, has encouraged research towards the development of easily reconfigurable and highly adaptable Web services. This work investigates the ability of Component-Based Software Development (CBSD) to produce such systems, and proposes a more manageable use of CBSD methodologies. Component-Driven Software Development (CDSD) is introduced to enable better component manageability. Current Web service technologies are also examined to determine their ability to support extensible Web services, and a dynamic Web service architecture is proposed. The work also describes the development of two proof-of-concept systems, DREW Chat and Hamilton Bank. DREW Chat and Hamilton Bank are implementations of Web services that support extension dynamically and at run-time. DREW Chat is implemented on the client side, where the user is given the ability to change the client as required. Hamilton Bank is a server-side implementation, which is run-time customisable by both the user and the party offering the service. In each case, a generic architecture is produced to support dynamic Web services. These architectures are combined to produce CREWS, a Component-driven Runtime Extensible Web Service solution that enables Web services to support the ever changing needs of enterprises. A discussion of similar work is presented, identifying the strengths and weaknesses of our architecture when compared to other solutions.
- Full Text:
- Date Issued: 2004
RADGIS - an improved architecture for runtime-extensible, distributed GIS applications
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
Virtual sculpting : an investigation of directly manipulated free-form deformation in a virtual environment
- Authors: Gain, James Edward
- Date: 1996
- Subjects: Computer simulation , Computer graphics , Virtual reality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4660 , http://hdl.handle.net/10962/d1006661 , Computer simulation , Computer graphics , Virtual reality
- Description: This thesis presents a Virtual Sculpting system, which addresses the problem of Free-Form Solid Modelling. The disparate elements of a Polygon-Mesh representation, a Directly Manipulated Free-Form Deformation sculpting tool, and a Virtual Environment are drawn into a cohesive whole under the mantle of a clay-sculpting metaphor. This enables a user to mould and manipulate a synthetic solid interactively as if it were composed of malleable clay. The focus of this study is on the interactivity, intuitivity and versatility of such a system. To this end, a range of improvements is investigated which significantly enhances the efficiency and correctness of Directly Manipulated Free-Form Deformation, both separately and as a seamless component of the Virtual Sculpting system.
- Full Text:
- Date Issued: 1996
- Authors: Gain, James Edward
- Date: 1996
- Subjects: Computer simulation , Computer graphics , Virtual reality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4660 , http://hdl.handle.net/10962/d1006661 , Computer simulation , Computer graphics , Virtual reality
- Description: This thesis presents a Virtual Sculpting system, which addresses the problem of Free-Form Solid Modelling. The disparate elements of a Polygon-Mesh representation, a Directly Manipulated Free-Form Deformation sculpting tool, and a Virtual Environment are drawn into a cohesive whole under the mantle of a clay-sculpting metaphor. This enables a user to mould and manipulate a synthetic solid interactively as if it were composed of malleable clay. The focus of this study is on the interactivity, intuitivity and versatility of such a system. To this end, a range of improvements is investigated which significantly enhances the efficiency and correctness of Directly Manipulated Free-Form Deformation, both separately and as a seamless component of the Virtual Sculpting system.
- Full Text:
- Date Issued: 1996
Extending the reach of personal area networks by transporting Bluetooth communications over IP networks
- Authors: Mackie, David Sean
- Date: 2007 , 2007-03-29
- Subjects: Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4637 , http://hdl.handle.net/10962/d1006551 , Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
- Description: This thesis presents an investigation of how to extend the reach of a Bluetooth personal area network by introducing the concept of Bluetooth Hotspots. Currently two Bluetooth devices cannot communicate with each other unless they are within radio range, since Bluetooth is designed as a cable-replacement technology for wireless communications over short ranges. An investigation was done into the feasibility of creating Bluetooth hotspots that allow distant Bluetooth devices to communicate with each other by transporting their communications between these hotspots via an alternative network infrastructure such as an IP network. Two approaches were investigated, masquerading of remote devices by the local hotspot to allow seamless communications and proxying services on remote devices by providing them on a local hotspot using a distributed service discovery database. The latter approach was used to develop applications capable of transporting Bluetooth’s RFCOMM and L2CAP protocols. Quantitative tests were performed to establish the throughput performance and latency of these transport applications. Furthermore, a number of selected Bluetooth services were tested which lead us to conclude that most data-based protocols can be transported by the system.
- Full Text:
- Date Issued: 2007
- Authors: Mackie, David Sean
- Date: 2007 , 2007-03-29
- Subjects: Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4637 , http://hdl.handle.net/10962/d1006551 , Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
- Description: This thesis presents an investigation of how to extend the reach of a Bluetooth personal area network by introducing the concept of Bluetooth Hotspots. Currently two Bluetooth devices cannot communicate with each other unless they are within radio range, since Bluetooth is designed as a cable-replacement technology for wireless communications over short ranges. An investigation was done into the feasibility of creating Bluetooth hotspots that allow distant Bluetooth devices to communicate with each other by transporting their communications between these hotspots via an alternative network infrastructure such as an IP network. Two approaches were investigated, masquerading of remote devices by the local hotspot to allow seamless communications and proxying services on remote devices by providing them on a local hotspot using a distributed service discovery database. The latter approach was used to develop applications capable of transporting Bluetooth’s RFCOMM and L2CAP protocols. Quantitative tests were performed to establish the throughput performance and latency of these transport applications. Furthermore, a number of selected Bluetooth services were tested which lead us to conclude that most data-based protocols can be transported by the system.
- Full Text:
- Date Issued: 2007
Adaptive flow management of multimedia data with a variable quality of service
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
Behavioural model debugging in Linda
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
Grouping complex systems for classification and parallel simulation
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
Towards a portable occam
- Authors: Hill, David Timothy
- Date: 1988 , 2013-03-07
- Subjects: occam (Computer program language) , Transputers , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4587 , http://hdl.handle.net/10962/d1004749 , occam (Computer program language) , Transputers , Parallel programming (Computer science)
- Description: Occam is designed for concurrent programming on a network of transputers. AIlocation and partitioning of the program is specified within the source code, binding the program to a specific network. An altemative approach is proposed which completely separates the source code from hardware considerations. Static allocation is performed as a separate phase and should, ideally, be automatic but at present is manual. Complete hardware abstraction requires that non-local, shared communication be provided for, introducing an efficiency overhead which can be minimised by the allocation. The proposal was implemented on a network of IBM PCs, modelled on a transputer network, and implementation issues are discussed
- Full Text:
- Date Issued: 1988
- Authors: Hill, David Timothy
- Date: 1988 , 2013-03-07
- Subjects: occam (Computer program language) , Transputers , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4587 , http://hdl.handle.net/10962/d1004749 , occam (Computer program language) , Transputers , Parallel programming (Computer science)
- Description: Occam is designed for concurrent programming on a network of transputers. AIlocation and partitioning of the program is specified within the source code, binding the program to a specific network. An altemative approach is proposed which completely separates the source code from hardware considerations. Static allocation is performed as a separate phase and should, ideally, be automatic but at present is manual. Complete hardware abstraction requires that non-local, shared communication be provided for, introducing an efficiency overhead which can be minimised by the allocation. The proposal was implemented on a network of IBM PCs, modelled on a transputer network, and implementation issues are discussed
- Full Text:
- Date Issued: 1988
A networking approach to sharing music studio resources
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
Parallel implementation of a virtual reality system on a transputer architecture
- Authors: Bangay, Shaun Douglas
- Date: 1994 , 2012-10-11
- Subjects: Virtual reality , Computer simulation , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4668 , http://hdl.handle.net/10962/d1006687 , Virtual reality , Computer simulation , Transputers
- Description: A Virtual Reality is a computer model of an environment, actual or imagined, presented to a user in as realistic a fashion as possible. Stereo goggles may be used to provide the user with a view of the modelled environment from within the environment, while a data-glove is used to interact with the environment. To simulate reality on a computer, the machine has to produce realistic images rapidly. Such a requirement usually necessitates expensive equipment. This thesis presents an implementation of a virtual reality system on a transputer architecture. The system is general, and is intended to provide support for the development of various virtual environments. The three main components of the system are the output device drivers, the input device drivers, and the virtual world kernel. This last component is responsible for the simulation of the virtual world. The rendering system is described in detail. Various methods for implementing the components of the graphics pipeline are discussed. These are then generalised to make use of the facilities provided by the transputer processor for parallel processing. A number of different decomposition techniques are implemented and compared. The emphasis in this section is on the speed at which the world can be rendered, and the interaction latency involved. In the best case, where almost linear speedup is obtained, a world containing over 250 polygons is rendered at 32 frames/second. The bandwidth of the transputer links is the major factor limiting speedup. A description is given of an input device driver which makes use of a powerglove. Techniques for overcoming the limitations of this device, and for interacting with the virtual world, are discussed. The virtual world kernel is designed to make extensive use of the parallel processing facilities provided by transputers. It is capable of providing support for mUltiple worlds concurrently, and for multiple users interacting with these worlds. Two applications are described that were successfully implemented using this system. The design of the system is compared with other recently developed virtual reality systems. Features that are common or advantageous in each of the systems are discussed. The system described in this thesis compares favourably, particularly in its use of parallel processors. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Bangay, Shaun Douglas
- Date: 1994 , 2012-10-11
- Subjects: Virtual reality , Computer simulation , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4668 , http://hdl.handle.net/10962/d1006687 , Virtual reality , Computer simulation , Transputers
- Description: A Virtual Reality is a computer model of an environment, actual or imagined, presented to a user in as realistic a fashion as possible. Stereo goggles may be used to provide the user with a view of the modelled environment from within the environment, while a data-glove is used to interact with the environment. To simulate reality on a computer, the machine has to produce realistic images rapidly. Such a requirement usually necessitates expensive equipment. This thesis presents an implementation of a virtual reality system on a transputer architecture. The system is general, and is intended to provide support for the development of various virtual environments. The three main components of the system are the output device drivers, the input device drivers, and the virtual world kernel. This last component is responsible for the simulation of the virtual world. The rendering system is described in detail. Various methods for implementing the components of the graphics pipeline are discussed. These are then generalised to make use of the facilities provided by the transputer processor for parallel processing. A number of different decomposition techniques are implemented and compared. The emphasis in this section is on the speed at which the world can be rendered, and the interaction latency involved. In the best case, where almost linear speedup is obtained, a world containing over 250 polygons is rendered at 32 frames/second. The bandwidth of the transputer links is the major factor limiting speedup. A description is given of an input device driver which makes use of a powerglove. Techniques for overcoming the limitations of this device, and for interacting with the virtual world, are discussed. The virtual world kernel is designed to make extensive use of the parallel processing facilities provided by transputers. It is capable of providing support for mUltiple worlds concurrently, and for multiple users interacting with these worlds. Two applications are described that were successfully implemented using this system. The design of the system is compared with other recently developed virtual reality systems. Features that are common or advantageous in each of the systems are discussed. The system described in this thesis compares favourably, particularly in its use of parallel processors. , KMBT_223
- Full Text:
- Date Issued: 1994
A machine-independent microprogram development system
- Authors: Ward, Michael John
- Date: 1987 , 2013-03-11
- Subjects: Microprogramming
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4581 , http://hdl.handle.net/10962/d1003738 , Microprogramming
- Description: The aims of this project are twofold. They are firstly, to implement a microprogram development system that allows the programmer to write microcode for any microprogrammable machine, and secondly, to build a microprogrammable machine, incorporating the user friendliness of a simulator, while still providing the 'hands on' experience obtained actual hardware. Microprogram development involves a two stage process. The first step is to describe the target machine, using format descriptions and mnemonic-based template definitions. The second stage involves using the defined mnemonics to write the microcodes for the target machine. This includes an assembly phase to translate the mnemonics into the binary microinstructions. Three main components constitute the microprogrammable machine. The Arithmetic and Logic Unit (ALU) is built using chips from Advanced Micro Devices' Am29ØØ bit-slice family, the action of the Microprogram Control Unit (MCU) is simulated by software running on an IBM Personal Computer, and a section of the IBM PC's main memory acts as the Control Store (CS) for the system. The ALU is built on a prototyping card that plugs into one of the slots on the IBM PC's mother board. A hardware simulator program, that produces the effect of the ALU, has also been developed. A small assembly language has been developed using the system, to test the various functions of the system. A mini-assembler has also been written to facilitate assembly of the above language. A group of honours students at Rhodes University tested the microprogram development system. Their ideas and suggestions have been tabulated in this report and some of them have been used to enhance the system's performance. The concept of allowing 'inline' microinstructions in the macroprogram is also investigated in this report and a method of implementing this is shown.
- Full Text:
- Date Issued: 1987
- Authors: Ward, Michael John
- Date: 1987 , 2013-03-11
- Subjects: Microprogramming
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4581 , http://hdl.handle.net/10962/d1003738 , Microprogramming
- Description: The aims of this project are twofold. They are firstly, to implement a microprogram development system that allows the programmer to write microcode for any microprogrammable machine, and secondly, to build a microprogrammable machine, incorporating the user friendliness of a simulator, while still providing the 'hands on' experience obtained actual hardware. Microprogram development involves a two stage process. The first step is to describe the target machine, using format descriptions and mnemonic-based template definitions. The second stage involves using the defined mnemonics to write the microcodes for the target machine. This includes an assembly phase to translate the mnemonics into the binary microinstructions. Three main components constitute the microprogrammable machine. The Arithmetic and Logic Unit (ALU) is built using chips from Advanced Micro Devices' Am29ØØ bit-slice family, the action of the Microprogram Control Unit (MCU) is simulated by software running on an IBM Personal Computer, and a section of the IBM PC's main memory acts as the Control Store (CS) for the system. The ALU is built on a prototyping card that plugs into one of the slots on the IBM PC's mother board. A hardware simulator program, that produces the effect of the ALU, has also been developed. A small assembly language has been developed using the system, to test the various functions of the system. A mini-assembler has also been written to facilitate assembly of the above language. A group of honours students at Rhodes University tested the microprogram development system. Their ideas and suggestions have been tabulated in this report and some of them have been used to enhance the system's performance. The concept of allowing 'inline' microinstructions in the macroprogram is also investigated in this report and a method of implementing this is shown.
- Full Text:
- Date Issued: 1987
Investigating call control using MGCP in conjuction with SIP and H.323
- Authors: Jacobs, Ashley
- Date: 2005 , 2005-03-14
- Subjects: Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4631 , http://hdl.handle.net/10962/d1006516 , Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Description: Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
- Full Text:
- Date Issued: 2005
- Authors: Jacobs, Ashley
- Date: 2005 , 2005-03-14
- Subjects: Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4631 , http://hdl.handle.net/10962/d1006516 , Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Description: Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
- Full Text:
- Date Issued: 2005
Modelling parallel and distributed virtual reality systems for performance analysis and comparison
- Authors: Bangay, Shaun Douglas
- Date: 1997
- Subjects: Virtual reality Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4657 , http://hdl.handle.net/10962/d1006656
- Description: Most Virtual Reality systems employ some form of parallel processing, making use of multiple processors which are often distributed over large areas geographically, and which communicate via various forms of message passing. The approaches to parallel decomposition differ for each system, as do the performance implications of each approach. Previous comparisons have only identified and categorized the different approaches. None have examined the performance issues involved in the different parallel decompositions. Performance measurement for a Virtual Reality system differs from that of other parallel systems in that some measure of the delays involved with the interaction of the separate components is required, in addition to the measure of the throughput of the system. Existing performance analysis approaches are typically not well suited to providing both these measures. This thesis describes the development of a performance analysis technique that is able to provide measures of both interaction latency and cycle time for a model of a Virtual Reality system. This technique allows performance measures to be generated as symbolic expressions describing the relationships between the delays in the model. It automatically generates constraint regions, specifying the values of the system parameters for which performance characteristics change. The performance analysis technique shows strong agreement with values measured from implementation of three common decomposition strategies on two message passing architectures. The technique is successfully applied to a range of parallel decomposition strategies found in Parallel and Distributed Virtual Reality systems. For each system, the primary decomposition techniques are isolated and analysed to determine their performance characteristics. This analysis allows a comparison of the various decomposition techniques, and in many cases reveals trends in their behaviour that would have gone unnoticed with alternative analysis techniques. The work described in this thesis supports the Performance Analysis and Comparison of Parallel and Distributed Virtual Reality systems. In addition it acts as a reference, describing the performance characteristics of decomposition strategies used in Virtual Reality systems.
- Full Text:
- Date Issued: 1997
- Authors: Bangay, Shaun Douglas
- Date: 1997
- Subjects: Virtual reality Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4657 , http://hdl.handle.net/10962/d1006656
- Description: Most Virtual Reality systems employ some form of parallel processing, making use of multiple processors which are often distributed over large areas geographically, and which communicate via various forms of message passing. The approaches to parallel decomposition differ for each system, as do the performance implications of each approach. Previous comparisons have only identified and categorized the different approaches. None have examined the performance issues involved in the different parallel decompositions. Performance measurement for a Virtual Reality system differs from that of other parallel systems in that some measure of the delays involved with the interaction of the separate components is required, in addition to the measure of the throughput of the system. Existing performance analysis approaches are typically not well suited to providing both these measures. This thesis describes the development of a performance analysis technique that is able to provide measures of both interaction latency and cycle time for a model of a Virtual Reality system. This technique allows performance measures to be generated as symbolic expressions describing the relationships between the delays in the model. It automatically generates constraint regions, specifying the values of the system parameters for which performance characteristics change. The performance analysis technique shows strong agreement with values measured from implementation of three common decomposition strategies on two message passing architectures. The technique is successfully applied to a range of parallel decomposition strategies found in Parallel and Distributed Virtual Reality systems. For each system, the primary decomposition techniques are isolated and analysed to determine their performance characteristics. This analysis allows a comparison of the various decomposition techniques, and in many cases reveals trends in their behaviour that would have gone unnoticed with alternative analysis techniques. The work described in this thesis supports the Performance Analysis and Comparison of Parallel and Distributed Virtual Reality systems. In addition it acts as a reference, describing the performance characteristics of decomposition strategies used in Virtual Reality systems.
- Full Text:
- Date Issued: 1997