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1
Dibley, James. "An investigation of the XMOS XSl architecture as a platform for development of audio control standards". Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1011789.
Testo completoAbstract (sommario):
This thesis investigates the feasiblity of using a new microcontroller architecture, the XMOS XS1, in the research and development of control standards for audio distribution networks. This investigation is conducted in the context of an emerging audio distribution network standard, Ethernet Audio/Video Bridging (`Ethernet AVB'), and an emerging audio control standard, AES-64. The thesis describes these emerging standards, the XMOS XS1 architecture (including its associated programming language, XC), and the open-source implementation of an Ethernet AVB streaming audio device based on the XMOS XS1 architecture. It is shown how the XMOS XS1 architecture and its associated features, focusing on the XC language's mechanisms for concurrency, event-driven programming, and integration of C software modules, enable a powerful implementation of the AES-64 control standard. Feasibility is demonstrated by the implementation of an AES-64 protocol stack and its integration into an XMOS XS1-based Ethernet AVB streaming audio device, providing control of Ethernet AVB features and audio hardware, as well as implementations of advanced AES-64 control mechanisms. It is demonstrated that the XMOS XS1 architecture is a compelling platform for the development of audio control standards, and has enabled the implementation of AES-64 connection management and control over standards-compliant Ethernet AVB streaming audio devices where no such implementation previously existed. The research additionally describes a linear design method for applications based on the XMOS XS1 architecture, and provides a baseline implementation reference for the AES-64 control standard where none previously existed.
2
Kheirkhah, Sabetghadam Morteza. "MMPTCP : a novel transport protocol for data centre networks". Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/61781/.
Testo completoAbstract (sommario):
Modern data centres provide large aggregate capacity in the backbone of networks so that servers can theoretically communicate with each other at their maximum rates. However, the Transport Control Protocol (TCP) cannot efficiently use this large capacity even if Equal-Cost Multi-Path (ECMP) routing is enabled to exploit the existence of parallel paths. MultiPath TCP (MPTCP) can effectively use the network resources of such topologies by performing fast distributed load balancing. MPTCP is an appealing technique for data centres that are very dynamic in nature. However, it is ill-suited for handling short flows since it increases their flow completion time. To mitigate these problems, we propose Maximum MultiPath TCP (MMPTCP), a novel transport protocol for modern data centres. Unlike MPTCP, it provides high performance for all network flows. It also decreases the bursty nature of data centres, which is essentially rooted in traffic patterns of short flows. MMPTCP achieves these nice features by randomising a flow's packets via all parallel paths to a destination during the initial phase of data transmission until a certain amount of data is delivered. It then switches to MPTCP with several subflows in which data transmission is governed by MPTCP congestion control. In this way, short flows are delivered very fast via the initial phase only, and long flows are delivered by MPTCP with several subflows. We evaluate MMPTCP in a FatTree topology under various network conditions. We found that MMPTCP decreases the loss rate of all the links throughout the network and helps competing flows to achieve a better performance. Unlike MPTCP with a fixed number of subflows, MMPTCP offers high burst tolerance and low-latency for short flows while it maintains high overall network utilisation. MMPTCP is incrementally deployable in existing data centres because it does not require any modification to the network and application layers.
3
Naicken, Stephen Murugapa. "Trusted content-based publish/subscribe trees". Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/38598/.
Testo completoAbstract (sommario):
Publish/Subscribe systems hold strong assumptions of the expected behaviour of clients and routers, as it is assumed they all abide by the matching and routing protocols. Assumptions of implicit trust between the components of the publish/subscribe infrastructure are acceptable where the underlying event distribution service is under the control of a single or multiple co-operating administrative entities and contracts between clients and these authorities exist, however there are application contexts where these presumptions do not hold. In such environments, such as ad hoc networks, there is the possibility of selfish and malicious behaviour that can lead to disruption of the routing and matching algorithms. The most commonly researched approach to security in publish/subscribe systems is role-based access control (RBAC). RBAC is suitable for ensuring confidentiality, but due to the assumption of strong identities associated with well defined roles and the absence of monitoring systems to allow for adaptable policies in response to the changing behaviour of clients, it is not appropriate for environments where: identities can not be assigned to roles in the absence of a trusted administrative entity; long-lived identities of entities do not exist; and where the threat model consists of highly adaptable malicious and selfish entities. Motivated by recent work in the application of trust and reputation to Peer-to-Peer networks, where past behaviour is used to generate trust opinions that inform future transactions, we propose an approach where the publish/subscribe infrastructure is constructed and re-configured with respect to the trust preferences of clients and routers. In this thesis, we show how Publish/Subscribe trees (PSTs) can be constructed with respect to the trust preferences of publishers and subscribers, and the overhead costs of event dissemination. Using social welfare theory, it is shown that individual trust preferences over clients and routers, which are informed by a variety of trust sources, can be aggregated to give a social preference over the set of feasible PSTs. By combining this and the existing work on PST overheads, the Maximum Trust PST with Overhead Budget problem is defined and is shown to be in NP-complete. An exhaustive search algorithm is proposed that is shown to be suitable only for very small problem sizes. To improve scalability, a faster tabu search algorithm is presented, which is shown to scale to larger problem instances and gives good approximations of the optimal solutions. The research contributions of this work are: the use of social welfare theory to provide a mechanism to establish the trustworthiness of PSTs; the finding that individual trust is not interpersonal comparable as is considered to be the case in much of the trust literature; the Maximum Trust PST with Overhead Budget problem; and algorithms to solve this problem.
4
Kant, Tanya. "Making it personal : web users and algorithmic personalisation". Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/65082/.
Testo completoAbstract (sommario):
This thesis investigates how web users negotiate and engage with contemporary algorithmic personalisation practices; that is, practices which seek to infer (via data tracking mechanisms and other algorithmic means) a user's habits, preferences or identity categorisations in order to ‘make personal' some component of that user's web experience. Drawing on thirty-six semi-structured interviews, I employ a qualitative methodology that seeks to bridge the gap between critical theorisations of algorithmic personalisation and the negotiations of web users themselves who encounter algorithmic personalisation in everyday life. To do this I focus on three sites of investigation. I first examine privacy tool Ghostery and the ways in which Ghostery users' negotiate their positions as data-tracked subjects, especially in relation to privacy, knowledge and their sense of self. I then investigate Facebook's autoposting apps as examples of algorithmic personalisation that act on the user's behalf, and draw on the accounts of Facebook app users to explore themes such as identity performance, autonomous control and algorithmic governance. Finally I examine users' engagement with the ‘predictive powers' (Google Now, 2014) of the personalisation app Google Now, specifically in regards to notions of user trust, expectation and speculation. My critical enquiries produced a number of themes that tie this thesis together. Central were: the epistemic uncertainties that emerged as trust and anxiety in participant responses; the implications for a performative understanding of selfhood when algorithmic personalisation intervenes in user self-articulation; the (asymmetrical) data-for-services exchange which web users must negotiate with commercial data trackers; and the struggle for autonomy between user and system that algorithmic personalisation creates. The thesis also argues that algorithmic personalisation demands that web users' identities be constituted as both a stable and fixable ‘single identity', but also as recursively reworkable, dividualised and endlessly expressable entities.
5
Cheong, Chi Po. "Participant Domain Name Token Profile for security enhancements supporting service oriented architecture". Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/49364/.
Testo completoAbstract (sommario):
This research proposes a new secure token profile for improving the existing Web Services security standards. It provides a new authentication mechanism. This additional level of security is important for the Service-Oriented Architecture (SOA), which is an architectural style that uses a set of principles and design rules to shape interacting applications and maintain interoperability. Currently, the market push is towards SOA, which provides several advantages, for instance: integration with heterogeneous systems, services reuse, standardization of data exchange, etc. Web Services is one of the technologies to implement SOA and it can be implemented using Simple Object Access Protocol (SOAP). A SOAP-based Web Service relies on XML for its message format and common application layer protocols for message negotiation and transmission. However, it is a security challenge when a message is transmitted over the network, especially on the Internet. The Organization for Advancement of Structured Information Standards (OASIS) announced a set of Web Services Security standards that focus on two major areas. “Who” can use the Web Service and “What” are the permissions. However, the location or domain of the message sender is not authenticated. Therefore, a new secure token profile called: Participant Domain Name Token Profile (PDNT) is created to tackle this issue. The PDNT provides a new security feature, which the existing token profiles do not address. Location-based authentication is achieved if adopting the PDNT when using Web Services. In the performance evaluation, PDNT is demonstrated to be significantly faster than other secure token profiles. The processing overhead of using the PDNT with other secure token profiles is very small given the additional security provided. Therefore all the participants can acquire the benefits of increased security and performance at low cost.
6
Tsietsi, Mosiuoa Jeremia. "Prototyping a peer-to-peer session initiation protocol user agent". Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1006603.
Testo completoAbstract (sommario):
The Session Initiation Protocol (SIP) has in recent years become a popular protocol for the exchange of text, voice and video over IP networks. This thesis proposes the use of a class of structured peer to peer protocols - commonly known as Distributed Hash Tables (DHTs) - to provide a SIP overlay with services such as end-point location management and message relay, in the absence of traditional, centralised resources such as SIP proxies and registrars. A peer-to-peer layer named OverCord, which allows the interaction with any specific DHT protocol via the use of appropriate plug-ins, was designed, implemented and tested. This layer was then incorporated into a SIP user agent distributed by NIST (National Institute of Standards and Technology, USA). The modified user agent is capable of reliably establishing text, audio and video communication with similarly modified agents (peers) as well as conventional, centralized SIP overlays.
7
McLean, Angus L. M. Thom III. "Real-time distributed simulation analysis : an application of temporal database and simulation systems research". Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/9124.
Testo completo
8
Tsai, Shang-Yuan. "Device profiling analysis in Device-Aware Network". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FTsai.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, December 2004.Thesis advisor(s): Singh Gurminder, John Gibson. Includes bibliographical references (p. 65-66). Also available online.
9
Foulkes, Philip James. "An investigation into the control of audio streaming across networks having diverse quality of service mechanisms". Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1004865.
Testo completoAbstract (sommario):
The transmission of realtime audio data across digital networks is subject to strict quality of service requirements. These networks need to be able to guarantee network resources (e.g., bandwidth), ensure timely and deterministic data delivery, and provide time synchronisation mechanisms to ensure successful transmission of this data. Two open standards-based networking technologies, namely IEEE 1394 and the recently standardised Ethernet AVB, provide distinct methods for achieving these goals. Audio devices that are compatible with IEEE 1394 networks exist, and audio devices that are compatible with Ethernet AVB networks are starting to come onto the market. There is a need for mechanisms to provide compatibility between the audio devices that reside on these disparate networks such that existing IEEE 1394 audio devices are able to communicate with Ethernet AVB audio devices, and vice versa. The audio devices that reside on these networks may be remotely controlled by a diverse set of incompatible command and control protocols. It is desirable to have a common network-neutral method of control over the various parameters of the devices that reside on these networks. As part of this study, two Ethernet AVB systems were developed. One system acts as an Ethernet AVB audio endpoint device and another system acts as an audio gateway between IEEE 1394 and Ethernet AVB networks. These systems, along with existing IEEE 1394 audio devices, were used to demonstrate the ability to transfer audio data between the networking technologies. Each of the devices is remotely controllable via a network neutral command and control protocol, XFN. The IEEE 1394 and Ethernet AVB devices are used to demonstrate the use of the XFN protocol to allow for network neutral connection management to take place between IEEE 1394 and Ethernet AVB networks. User control over these diverse devices is achieved via the use of a graphical patchbay application, which aims to provide a consistent user interface to a diverse range of devices.
10
Mascarenhas, da Veiga Alves Manoel Eduardo. "Characterisation of end-to-end performance for web-based file server respositories". Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ENS/09ensm395.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 128-135. Investigates the behaviour of TCP bulk file transfer application sessions in a broadband access environment. Introduces some concepts for evaluating network behaviour: a path instability parameter for analyzing different TCP connections; a minimum RTT delay and a minimum typical path for estimating path characteristics between a client and application servers.
11
Klaška, Patrik. "Návrh autentizace uživatelů ve společnosti". Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2018. http://www.nusl.cz/ntk/nusl-378339.
Testo completoAbstract (sommario):
This thesis is focused on the creation of functional authentication process of users into computer network in company Wistron InfoComm s.r.o. and discusses issues related to this process. The main aim of the thesis is to implement a functional and simultaneously realistic solution based on the company's requirements as well as described problems associated with the implementation of this solution.
12
Hsiao, Chih-Wen, David Turner e Keith Ross. "A secure lightweight currency service provider". CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2594.
Testo completoAbstract (sommario):
The main purpose of this project is to build a bank system that offers a friendly and simple interface to let users easily manage their lightweight currencies. The Lightweight Currency Protocol (LCP) was originally proposed to solve the problem of fairness in resource cooperatives. However, there are other possible applications of the protocol, including the control of spam and as a general purpose medium of exchange for low value transactions. This project investigates the implementation issues of the LCP, and also investigates LCP bank services to provide human interface to currency operations.
13
Konga, Yannick Lokombo Kala. "Formal specification and verification of peer-to-peer network protocols". 2011. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000638.
Testo completoAbstract (sommario):
M. Tech. Electrical Engineering.This research presented an integrated formal model of the JXTA protocol suite. The integrated model is constructed from the individual models describing the behaviours of protocols entities. Written in the PROMELA specification language, the finite state automata of these models are shown instead. The SPIN-based formal verification revealed that this studys integrated model was too large to perform for the computational resources available. This was in spite of the application of multiple complexity reduction techniques. Subsequently, as final recourse, the research resorted to the formal verification of individual protocols by making further abstraction of the interaction and dependencies between protocols. A number of errors were found including an invalid end state in the routing protocols and multiple non-progress cycles.
14
Srinivasan, Suman Ramkumar. "Improving Content Delivery and Service Discovery in Networks". Thesis, 2016. https://doi.org/10.7916/D8Z89CCC.
Testo completoAbstract (sommario):
Production and consumption of multimedia content on the Internet is rising, fueled by the demand for content from services such as YouTube, Netflix and Facebook video. The Internet is shifting from host-based to content-centric networking. At the same time, users are shifting away from a homogeneous desktop computing environment to using a heterogeneous mix of devices, such as smartphones, tablets and thin clients, all of which allow users to consume data on the move using wireless and cellular data networks.
The popularity of these new class of devices has, in turn, increased demand for multimedia content by mobile users. The emergence of rich Internet applications and the widespread adoption and use of High Definition (HD) video has also placed higher pressure on the service providers and the core Internet backbone, forcing service providers to respond to increased bandwidth use in such networks.
In my thesis, I aim to provide clarity and insight into the usage of core networking protocols and multimedia consumption on both mobile and wireless networks, as well as the network core. I also present research prototypes for potential solutions to some of the problems caused by the increased multimedia consumption on the Internet.
15
Chen, Mingye. "Performance evaluation of routing protocols using NS-2 and realistic traces on driving simulator". Thesis, 2014. http://hdl.handle.net/1805/4437.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)With the rapid growth in wireless mobile communication technology, Vehicular Ad-hoc Network (VANET) has emerged as a promising method to effectively solve transportation-related issues. So far, most of researches on VANETs have been conducted with simulations as the real-world experiment is expensive. A core problem affecting the fidelity of simulation is the mobility model employed. In this thesis, a sophisticated traffic simulator capable of generating realistic vehicle traces is introduced. Combined with network simulator NS-2, we used this tool to evaluate the general performance of several routing protocols and studied the impact of intersections on simulation results. We show that static nodes near the intersection tend to become more active in packet delivery with higher transferred throughput.
16
Kabiwa, Tchokonte Maxime Stephane. "Development of an improved link metric for routing protocols in wireless ad-hoc networks". 2014. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001649.
Testo completoAbstract (sommario):
M. Tech. Electrical engineering.Discusses the interference and bandwidth adjusted ETX routing metric uses a logical interference model that refers to the interference arising from the Carrier Sensing Multiple Access with Collision Avoidance (CSMA-CA) based Medium Access Control. This approach of capturing inter-flow is complex and more restrictive. In this dissertation, a more realistic and less restrictive approach based on the information available at the physical layer (signal strength) is used to capture the interference.In contrast to the logical interference model, this has the excellent advantage of measuring the parameters using online data traffic. The question is whether actual capacity improvements can be achieved by considering the physical interference model.
17
Mahlaba, Simon Bonginkosi. "A MAC protocol for IP-based CDMA wireless networks". Thesis, 2005. http://hdl.handle.net/10413/2772.
Testo completoAbstract (sommario):
The evolution of the intemet protocol (IP) to offer quality of service
(QoS) makes it a suitable core network protocol for next generation
networks (NGN). The QoS features incorporated to IP will enable future lP-based wireless networks to meet QoS requirements of various multimedia traffic. The Differentiated Service (Diffserv) Architecture is a promising QoS technology due to its scalability which arises from traffic flow aggregates. For this reason, in this dissertation a network infrastructure based on DiffServ is assumed. This architecture provides assured service (AS) and premium service (PrS) classes in addition to best-effort service (BE). The medium access control (MAC) protocol is one of the important design issues in wireless networks. In a wireless network carrying multimedia traffic, the MAC protocol is required to provide simultaneous support for a wide variety of traffic types, support traffic with delay and jitter bounds, and assign bandwidth in an efficient and fair manner among traffic classes. Several MAC protocols capable of supporting multimedia services have been proposed in the literature, the majority of which were designed for wireless A1M (Asynchronous Transfer Mode). The focus of this dissertation is on time division multiple access and code division multiple access (TDMAlCDMA)
based MAC protocols that support QoS in lP-based wireless networks. This dissertation begins by giving a survey of wireless MAC protocols. The survey considers MAC protocols for centralised wireless networks and classifies them according to their multiple access technology and as well as their method of resource sharing. A novel TDMAlCDMA based MAC protocol incorporating techniques from existing protocols is then proposed. To provide the above-mentioned services, the bandwidth is partitioned amongst AS and PrS classes. The BE class utilizes the remaining bandwidth from the two classes because it does not have QoS requirements. The protocol employs a demand assignment (DA) scheme to support traffic from PrS and AS classes. BE traffic is supported by a random reservation access scheme with dual multiple access interference (MAl) admission thresholds. The performance of the protocol, i.e. the AS or PrS call blocking probability, and BE throughput are evaluated
through Markov analytical models and Monte-Carlo simulations.
Furthermore, the protocol is modified and incorporated into IEEE 802.16 broadband wireless access (BWA) network.Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.
18
Zare, Afifi Saharnaz. "Securing sensor network". Thesis, 2014. http://hdl.handle.net/1805/6186.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)A wireless sensor network consists of lightweight nodes with a limited power source. They can be used in a variety of environments, especially in environments for which it is impossible to utilize a wired network. They are easy/fast to deploy. Nodes collect data and send it to a processing center (base station) to be analyzed, in order to detect an event and/or determine information/characteristics of the environment. The challenges for securing a sensor network are numerous. Nodes in this network have a limited amount of power, therefore they could be faulty because of a lack of battery power and broadcast faulty information to the network. Moreover, nodes in this network could be prone to different attacks from an adversary who tries to eavesdrop, modify or repeat the data which is collected by other nodes. Nodes may be mobile. There is no possibility of having a fixed infrastructure. Because of the importance of extracting information from the data collected by the sensors in the network there needs to be some level of security to provide trustworthy information. The goal of this thesis is to organize part of the network in an energy efficient manner in order to produce a suitable amount of integrity/security. By making nodes monitor each other in small organized clusters we increase security with a minimal energy cost. To increase the security of the network we use cryptographic techniques such as: public/ private key, manufacturer signature, cluster signature, etc. In addition, nodes monitor each other's activity in the network, we call it a "neighborhood watch" In this case, if a node does not forward data, or modifies it, and other nodes which are in their transmission range can send a claim against that node.
19
Pamulapati, Santhan. "Link failure detection in OSPF network using OpenFlow protocol". Thesis, 2014. http://hdl.handle.net/1805/4443.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)The study of this thesis is focused on reducing the link failure detection time in OSPF network. When a link failure occurs, OSPF protocol detects it using RouterDeadInterval time. This timer is fired only after a predefined time interval, thus increasing the time of convergence after the link failure. There are previous studies to reduce the RouterDeadInterval time, but they introduce other effects which are discussed later in the thesis. So, a novel approach is proposed in this thesis to reduce the link failure detection time with the help of emerging network architecture Software Defined Networking (SDN) and OpenFlow Protocol.
20
Pandita, Shreya. "OpenFlow based load balancing and proposed theory for integration in VoIP network". Thesis, 2014. http://hdl.handle.net/1805/4444.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)In today's internet world with such a high traffic, it becomes inevitable to have multiple servers representing a single logical server to share enormous load. A very common network configuration consists of multiple servers behind a load balancer. The load balancer determines which server would service a clients request or incoming load from the client. Such a hardware is expensive, runs a fixed policy or algorithm and is a single point of failure. In this paper, we will implement and analyze an alternative load balancing architecture using OpenFlow. This architecture acquires flexibility in policy, costs less and has the potential to be more robust. This paper also discusses potential usage of OpenFlow based load balancing for media gateway selection in SIP-PSTN networks to improve VoIP performance.
21
Lu, Zebin. "SECURE WEB APPLICATIONS AGAINST OFF-LINE PASSWORD GUESSING ATTACK: A TWO WAY PASSWORD PROTOCOL WITH CHALLENGE RESPONSE USING ARBITRARY IMAGES". 2013. http://hdl.handle.net/1805/3425.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)The web applications are now being used in many security oriented areas, including online shopping, e-commerce, which require the users to transmit sensitive information on the Internet. Therefore, to successfully authenticate each party of web applications is very important. A popular deployed technique for web authentication is the Hypertext Transfer Protocol Secure (HTTPS) protocol. However the protocol does not protect the careless users who connect to fraudulent websites from being trapped into tricks. For example, in a phishing attack, a web user who connects to an attacker may provide password to the attacker, who can use it afterwards to log in the target website and get the victim’s credentials. To prevent phishing attacks, the Two-Way Password Protocol (TPP) and Dynamic Two-Way Password Protocol (DTPP) are developed. However there still exist potential security threats in those protocols. For example, an attacker who makes a fake website may obtain the hash of users’ passwords, and use that information to arrange offline password guessing attacks. Based on TPP, we incorporated challenge responses with arbitrary images to prevent the off-line password guessing attacks in our new protocol, TPP with Challenge response using Arbitrary image (TPPCA). Besides TPPCA, we developed another scheme called Rain to solve the same problem by dividing shared secrets into several rounds of negotiations. We discussed various aspects of our protocols, the implementation and experimental results.
22
Puranik, Darshan Gajanan. "Real-time monitoring of distributed real-time and embedded systems using Web". 2014. http://hdl.handle.net/1805/3801.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)Asynchronous JavaScript and XML (AJAX) is the primary method for enabling asynchronous communication over the Web. Although AJAX is providing warranted real-time capabilities to the Web, it requires unconventional programming methods at the expense of extensive resource usage. WebSockets, which is an emerging protocol, has the potential to address many challenges with implementing asynchronous communication over the Web. There, however, has been no in-depth study that quantitatively compares AJAX and WebSockets. This thesis therefore provides two contributions to Web development. First, it provides an experience report for adding real-time monitoring support over the Web to the Open-source Architecture of Software Instrumentation of Systems(OASIS), which is open-source real-time instrumentation middleware for distributed real-time and embedded (DRE) systems. Secondly, it quantitatively compares using AJAX and WebSockets to stream collected instrumentation data over the Web in real-time. Results from quantitative comparison between WebSockets and AJAX show that a WebSockets server consumes 50% less network bandwidth than an AJAX server; a WebSockets client consumes memory at constant rate, not at an increasing rate; and WebSockets can send up to 215.44% more data samples when consuming the same amount network bandwidth as AJAX.
23
Marais, Hester 1961. "Authority control in an academic library consortium using a union catalogue maintained by a central office for authority control". Thesis, 2004. http://hdl.handle.net/10500/2546.
Testo completoAbstract (sommario):
Authority control is the backbone of the library catalogue and therefore a critical library activity. Experienced staff create authority records to assist users in their quest for information. The focus of this study is on authority control as a means of co-operation in academic library consortia using a union catalogue maintained by a Central Office for Authority Control.
Literature studies were conducted on three sub-problems: the development of academic library consortia in South Africa, and various forms, characteristics and functions of academic library consortia in general; the characteristics, principals and objectives of authority control; and the functions of union catalogues with special reference to the role of Z39.50 within virtual union catalogues. The conclusion was that existing and new authority records should be made available as widely as possible within consortia through a union catalogue. It is however a partial solution, because not all the libraries within the consortium have the expertise to create new authority records.
Two empirical studies were conducted. A cost analysis was done to determine the cost of creating and changing authority records within academic library consortia in South Africa, in order to choose a system within which authority control can be performed effectively and speedily.
Secondly, a questionnaire was sent to libraries in the United States to gather information on their experiences with regard to authority control, library co-operation in general, and virtual union catalogues. The United States was the natural choice because it could be regarded as the birthplace of modern library consortia. Inferences drawn from the information received was used to develop the structure and functions for a Central Office for Authority Control in academic library consortia in South Africa.
It was found that authority control within an academic library consortium using a union catalogue could be conducted most cost-effectively and timeously through such a Central Office for Authority Control. The purpose of the Central Office would be to co-ordinate authority control within the consortium. Pooling available resources within the consortium would keep the cost of authority control as low as possible. Libraries with the required infrastructure and expertise would have the opportunity to create authority records on behalf of other libraries and be compensated for their services. Through such a Central Office more authority records created according to mutually accepted standards would be available for sharing within the consortium.Information Science
D.Litt. et Phil. (Information Science)