Optimising data centre operation by removing the transport bottleneck

Data centres lie at the heart of almost every service on the Internet. Data centres are used to provide search results, to power social media, to store and index email, to host “cloud” applications, for online retail and to provide a myriad of other web services. Consequently the more efficient they can be made the better for all of us. The power of modern data centres is in combining commodity off-the-shelf server hardware and network equipment to provide what Google’s Barrosso and Ho ̈lzle describe as “warehouse scale” computers. Data centres rely on TCP, a transport protocol that was originally designed for use in the Internet. Like other such protocols, TCP has been optimised to maximise throughput, usually by filling up queues at the bottleneck. However, for most applications within a data centre network latency is more critical than throughput. Consequently the choice of transport protocol becomes a bottleneck for performance. My thesis is that the solution to this is to move away from the use of one-size-fits-all transport protocols towards ones that have been designed to reduce latency across the data centre and which can dynamically respond to the needs of the applications. This dissertation focuses on optimising the transport layer in data centre networks. In particular I address the question of whether any single transport mechanism can be flexible enough to cater to the needs of all data centre traffic. I show that one leading protocol (DCTCP) has been heavily optimised for certain network conditions. I then explore approaches that seek to minimise latency for applications that care about it while still allowing throughput-intensive applications to receive a good level of service. My key contributions to this are Silo and Trevi. Trevi is a novel transport system for storage traffic that utilises fountain coding to max- imise throughput and minimise latency while being agnostic to drop, thus allowing storage traffic to be pushed out of the way when latency sensitive traffic is present in the network. Silo is an admission control system that is designed to give tenants of a multi-tenant data centre guaranteed low latency network performance. Both of these were developed in collaboration with others

Combining SOA and BPM Technologies for Cross-System Process Automation

This paper summarizes the results of an industry case study that introduced a cross-system business process automation solution based on a combination of SOA and BPM standard technologies (i.e., BPMN, BPEL, WSDL). Besides discussing major weaknesses of the existing, custom-built, solution and comparing them against experiences with the developed prototype, the paper presents a course of action for transforming the current solution into the proposed solution. This includes a general approach, consisting of four distinct steps, as well as specific action items that are to be performed for every step. The discussion also covers language and tool support and challenges arising from the transformation

The design, development and evaluation of cross-platform mobile applications and services supporting social accountability monitoring

Local government processes require meaningful and effective participation from both citizens and their governments in order to remain truly democratic. This project investigates the use of mobile phones as a tool for supporting this participation. MobiSAM, a system which aims to enhance the Social Accountability Monitoring (SAM) methodology at local government level, has been designed and implemented. The research presented in this thesis examines tools and techniques for the development of cross-platform client applications, allowing access to the MobiSAM service, across heterogeneous mobile platforms, handsets and interaction styles. Particular attention is paid to providing an easily navigated user interface (UI), as well as offering clear and concise visualisation capabilities. Depending on the host device, interactivity is also included within these visualisations, potentially helping provide further insight into the visualised data. Guided by the results obtained from a comprehensive baseline study of the Grahamstown area, steps are taken in an attempt to lower the barrier of entry to using the MobiSAM service, potentially maximising its market reach. These include extending client application support to all identified mobile platforms (including feature phones); providing multi-language UIs (in English, isiXhosa and Afrikaans); as well as ensuring client application data usage is kept to a minimum. The particular strengths of a given device are also leveraged, such as its camera capabilities and built-in Global Positioning System (GPS) module, potentially allowing for more effective engagement with local municipalities. Additionally, a Short Message Service (SMS) gateway is developed, allowing all Global System for Mobile Communications (GSM) compatible handsets access to the MobiSAM service via traditional SMS. Following an iterative, user-centred design process, a thorough evaluation of the client application is also performed, in an attempt to gather feedback relating to the navigation and visualisation capabilities. The results of which are used to further refine its design. A comparative usability evaluation using two different versions of the cross-platform client application is also undertaken, highlighting the perceived memorability, learnabilitv and satisfaction of each. Results from the evaluation reveals which version of the client application is to be deployed during future pilot studies

Development and management of collective network and cloud computing infrastructures

Pla de Doctorat industrial de la Generalitat de CatalunyaIn the search and development of more participatory models for infrastructure development and management, in this dissertation, we investigate models for the financing, deployment, and operation of network and cloud computing infrastructures. Our main concern is to overcome the inherent exclusion in participation in the processes of development and management and in the right of use in the current dominant models. Our work starts by studying in detail the model of Guifi.net, a successful bottom-up initiative for building network infrastructure, generally referred to as a community networks. We pay special attention to its governance system and economic organisation because we argue that these are the key components of the success of this initiative. Then, we generalise our findings for any community network, aiming at becoming sustainable and scalable, and we explore the suitability of the Guifi.net model to the cloud computing infrastructure. As a result of both, we coin the attribute extensible to refer to infrastructure that is relatively easy to expand and maintain in contrast to those naturally limited or hard to expand, such as natural resources or highly complex or advanced artificial systems. We conclude proposing a generic model which, in our opinion, is suitable, at least, for managing extensible infrastructure. The Guifi.net model is deeply rooted in the commons; thus, the research in this field, in general, and Elinor Ostrom’s work, in particular, have left a profound imprint in our work. Our results show that the \guifinet model meets almost entirely the principles of long-enduring commons identified by E. Ostrom. This work has been developed as an industrial doctorate. As such, it combines academic research with elements of practice and pursues an effective knowledge transfer between academia and the private sector. Given that the private sector’s partner is a not-for-profit organisation, the effort to create social value has prevailed over the ambition to advance the development of a specific industrial product or particular technology.En la recerca i desenvolupament de models més participatius per al desenvolupament i gestió d'infraestructura, en aquesta tesi investiguem sobre models per al finançament, desplegament i operació d'infraestructures de xarxa i de computació al núvol. La nostra preocupació principal és fer front a l’exclusió inherent dels models dominants actualment pel que fa a la participació en els processos de desenvolupament i gestió i, també, als drets d’us. El nostre treball comença amb un estudi detallat del model de Guifi.net, un cas d'èxit d'iniciativa ciutadana en la construcció d'infraestructura de xarxa, iniciatives que es coneixen com a xarxes comunitàries. En fer-ho, parem una atenció especial al sistema de governança i a l’organització econòmica perquè pensem que són els dos elements claus de l'èxit d'aquesta iniciativa. Tot seguit passem a analitzar d'altres xarxes comunitàries per abundar en la comprensió dels factors determinants per a la seva sostenibilitat i escalabilitat. Després ampliem el nostre estudi analitzant la capacitat i el comportament del model de Guifi.net en el camp de les infraestructures de computació al núvol. A resultes d'aquests estudis, proposem l'atribut extensible per a descriure aquelles infraestructures que són relativament fàcil d'ampliar i gestionar, en contraposició a les que o bé estan limitades de forma natural o be són difícils d'ampliar, com ara els recursos naturals o els sistemes artificials avançats o complexos. Finalitzem aquest treball fent una proposta de model genèric que pensem que és d'aplicabilitat, com a mínim, a tot tipus d'infraestructura extensible. El model de Guifi.net està fortament vinculat als bens comuns. És per això que la recerca en aquest àmbit, en general, i els treballs de Elinor Ostrom en particular, han deixat una forta empremta en el nostre treball. Els resultats que hem obtingut mostren que el model Guifi.net s'ajusta molt bé als principis que segons Ostrom han de complir els béns comuns per ser sostenibles. Aquest treball s'ha desenvolupat com a doctorat industrial. Com a tal, combina la investigació acadèmica amb elements de practica i persegueix una transferència efectiva de coneixement entre l'àmbit acadèmic i el sector privat. Ates que el soci del sector privat és una organització sense ànim de lucre, l’esforç per crear valor social ha prevalgut en l’ambició d’avançar en el desenvolupament d'un producte industrial específic o d'una tecnologia particularPostprint (published version

Development and management of collective network and cloud computing infrastructures

In the search and development of more participatory models for infrastructure development and management, in this dissertation, we investigate models for the financing, deployment, and operation of network and cloud computing infrastructures. Our main concern is to overcome the inherent exclusion in participation in the processes of development and management and in the right of use in the current dominant models. Our work starts by studying in detail the model of Guifi.net, a successful bottom-up initiative for building network infrastructure, generally referred to as a community networks. We pay special attention to its governance system and economic organisation because we argue that these are the key components of the success of this initiative. Then, we generalise our findings for any community network, aiming at becoming sustainable and scalable, and we explore the suitability of the Guifi.net model to the cloud computing infrastructure. As a result of both, we coin the attribute extensible to refer to infrastructure that is relatively easy to expand and maintain in contrast to those naturally limited or hard to expand, such as natural resources or highly complex or advanced artificial systems. We conclude proposing a generic model which, in our opinion, is suitable, at least, for managing extensible infrastructure. The Guifi.net model is deeply rooted in the commons; thus, the research in this field, in general, and Elinor Ostrom’s work, in particular, have left a profound imprint in our work. Our results show that the \guifinet model meets almost entirely the principles of long-enduring commons identified by E. Ostrom. This work has been developed as an industrial doctorate. As such, it combines academic research with elements of practice and pursues an effective knowledge transfer between academia and the private sector. Given that the private sector’s partner is a not-for-profit organisation, the effort to create social value has prevailed over the ambition to advance the development of a specific industrial product or particular technology.En la recerca i desenvolupament de models més participatius per al desenvolupament i gestió d'infraestructura, en aquesta tesi investiguem sobre models per al finançament, desplegament i operació d'infraestructures de xarxa i de computació al núvol. La nostra preocupació principal és fer front a l’exclusió inherent dels models dominants actualment pel que fa a la participació en els processos de desenvolupament i gestió i, també, als drets d’us. El nostre treball comença amb un estudi detallat del model de Guifi.net, un cas d'èxit d'iniciativa ciutadana en la construcció d'infraestructura de xarxa, iniciatives que es coneixen com a xarxes comunitàries. En fer-ho, parem una atenció especial al sistema de governança i a l’organització econòmica perquè pensem que són els dos elements claus de l'èxit d'aquesta iniciativa. Tot seguit passem a analitzar d'altres xarxes comunitàries per abundar en la comprensió dels factors determinants per a la seva sostenibilitat i escalabilitat. Després ampliem el nostre estudi analitzant la capacitat i el comportament del model de Guifi.net en el camp de les infraestructures de computació al núvol. A resultes d'aquests estudis, proposem l'atribut extensible per a descriure aquelles infraestructures que són relativament fàcil d'ampliar i gestionar, en contraposició a les que o bé estan limitades de forma natural o be són difícils d'ampliar, com ara els recursos naturals o els sistemes artificials avançats o complexos. Finalitzem aquest treball fent una proposta de model genèric que pensem que és d'aplicabilitat, com a mínim, a tot tipus d'infraestructura extensible. El model de Guifi.net està fortament vinculat als bens comuns. És per això que la recerca en aquest àmbit, en general, i els treballs de Elinor Ostrom en particular, han deixat una forta empremta en el nostre treball. Els resultats que hem obtingut mostren que el model Guifi.net s'ajusta molt bé als principis que segons Ostrom han de complir els béns comuns per ser sostenibles. Aquest treball s'ha desenvolupat com a doctorat industrial. Com a tal, combina la investigació acadèmica amb elements de practica i persegueix una transferència efectiva de coneixement entre l'àmbit acadèmic i el sector privat. Ates que el soci del sector privat és una organització sense ànim de lucre, l’esforç per crear valor social ha prevalgut en l’ambició d’avançar en el desenvolupament d'un producte industrial específic o d'una tecnologia particula

Mine Action: Lessons and Challenges

Mine Action: Lessons and Challenges represents the views of selected experts as to what some of the key lessons have been, and what challenges remain for the future. Following an Executive Summary of its main conclusions and findings, this work is laid out in two parts. Part I looks at the core activities — the “pillars” — of mine action: advocacy, victim assistance, mine risk education, demining (survey, marking and clearance of mines and unexploded ordnance) and stockpile destruction. Part II looks at key management issues, specifically, programme coordination and management, information management and capacity development. This work concludes with a thought-provoking assessment of what mine action has actually achieved

Helping developers to help each other: a technique to facilitate understanding among professional software developers.

Much of a professional software developer’s work involves amending or extending pre-existing software; creating new software from scratch represents only a small proportion of their time. Even in a brand new project they still need to make sense of work others have done in the emerging software system. This research addresses how developers are helped or hindered in their own daily tasks by the actions of their peers. The literature commonly focuses on a specific aspect of the work such as code comprehension or the processes by which a project is run. This research instead takes a holistic view that considers all the activities involved in the job, but from a single uniting perspective: rather than conventional measures such as coding errors or delivery timescales, the criterion here is how a developer personally experiences their own productivity to be affected by their peers. The research used one-to-one interviews to identify common behaviours that help or hinder fellow software developers. Experienced software developers discussed team- friendly (and otherwise) behaviours across the breadth of their typical workplace tasks. The key themes to emerge from this qualitative data make a contribution to the understanding of software development by giving a comprehensive, developer’s- eye view of behaviours that help or hinder them across the whole range of tasks that fill their days. These themes laid the foundation for a practical application of the research. Techniques which had proved engaging and useful in the interviews were adapted into a continuing professional development workshop designed to encourage team discussion on issues of local resonance, selected by participants from those which the interviews had shown to be important. The topics resonated in a way which reinforces the validity of the interview findings. Participants enthusiastically identified useful actions for their own teams and would recommend the workshop to others. They also saw potential for future development into different workplace scenarios. The workshop is just one application of the understanding contributed by the research. The principles of good practice from the human perspective that have been identified also offer an empirical foundation that could be of practical use in appraisals, recruitment and any other scenario which requires an understanding of software developers not just as computer programmers but as people

Operational managers handbook to information technology outsourcing

The academic, consulting, and business community is inundated with books, articles, web sites, and consulting services devoted to IT Outsourcing. As the technology advances and the business community gains practical experience in the area, outsourcing options require constant updating. This handbook provides the sequence of business process steps along with numerous guidelines, checklists, and detailed descriptions for developing a successful outsourcing contract. What is unique about the handbook is that it synthesizes the organizational, cultural, and political aspects of the enterprise that form the underpinnings for the development of a successful outsourcing function within the enterprise. The handbook then delves into the formation of a successful contracting team describing the skill set of the team members and their organization from the planning through the implementation stages of the outsourcing process. Last, the handbook provides the content detail and rationale of the three stages of contract formulation - Request For Information (RFI); Request For Proposal; and the Contract itself

Multi-perspective modelling for knowledge management and knowledge engineering

ii It seems almost self-evident that “knowledge management ” and “knowledge engineering” should be related disciplines that may share techniques and methods between them. However, attempts by knowledge engineers to apply their techniques to knowledge management have been praised by some and derided by others, who claim that knowledge engineers have a fundamentally wrong concept of what “knowledge management” is. The critics also point to specific weaknesses of knowledge engineering, notably the lack of a broad context for the knowledge. Knowledge engineering has suffered some criticism from within its own ranks, too, particularly of the “rapid prototyping ” approach, in which acquired knowledge was encoded directly into an iteratively developed computer system. This approach was indeed rapid, but when used to deliver a final system, it became nearly impossible to verify and validate the system or to maintain it. A solution to this has come in the form of knowledge engineering methodology, and particularly in the CommonKAD