Cloud Federation Formation: Enabling Factors, Requirements, Challenges, and Current Trends with an Emphasis on Institutional Trust and Distributed Trust Evaluation = 클라우드 연합 형성: 기관 신뢰도와 분산 신뢰도 평가를 통한 요인, 요구사항, 과제 및 현재 동향 지원

국문 초록 (Abstract)

클라우드 컴퓨팅은, 소비자들에게 신기술에 대한 접근, 혁신성 및 확장성 등 다양한 혜택을 제공하며 빠르게 성장하고 있다. 그러나 클라우드 컴퓨팅 시장은 주로 대기업의 영향력이 지배적이어서, 중소규모의 클라우드 공급자들의 시장 경쟁력이 제한되고 있다. 중소규모 클라우드 공급자들의 경쟁력 향상을 위해, 서로 다른 목적을 가진 여러 클라우드 공급자를 활용하는 멀티 클라우드 전략(multi-cloud strategy)을 채택할 수 있다. 이러한 멀티 클라우드 전략을 구현하는 한가지 방법에는 클라우드 연합(cloud federation)이 있는데, 클라우드 연합은 클라우드 공급자가 필요에 따라 다른 공급자의 서비스를 사고 팔 수 있게 하는 것으로, 클라우드 서비스의 안정성을 높이고, 비용과 에너지 소비를 줄이며, 리소스를 쉽게 확장하는 장점을 가지고 있다.
본 논문은, 클라우드 연합 형성에 대한 설득력 있고 포괄적인 조사를 수행하는데 그 목적이 있으며, 이를 위해 두가지 주요 연구가 수행되었다. 첫번째 연구는, 클라우드 연합 형성에 대한 기여 요인, 요구사항, 도전 과제, 현재 동향과 관련한 체계적인 문헌 고찰(systematic literature review)을 진행하였다. 그리고 문헌 고찰을 토대로, 혁신적인 기관 품질 인식 신뢰 클라우드 연합 형성 (Institutional Quality-Aware Trusted Cloud Federation Formation) 방법을 제안하였으며, 이를 통해 클라우드 연합 형성의 복잡성과 불확실성을 해결할 수 있도록 하였다. 또한, 제안된 방법으로, 새로운 클라우드 연합의 전체 아키텍처와 연합 형성 알고리즘을 도입하고, 클라우드 서비스 공급자가 신뢰할 수 있는 파트너를 선택할 수 있도록 2단계 신뢰 평가 프로세스를 제안하였다.
본 연구에서는, 클라우드 연합 형성을 포괄적으로 조사하기 위해 6개의 연구 질문을 설정하였다. 첫번째 연구인 체계적 문헌 검토(systematic literature review)를 통해서는 6개 연구 질문 중 4개의 연구 질문을 다루었으며, 16가지 클라우드 연합 구성 활성화 요인, 17가지 요구 사항, 18가지 주요 과제를 성공적으로 확인하였다. 활성화 요인 중에서 리소스 프로비저닝(provisioning)과 유연성이 가장 많이 논의되는 요인이었으며, 법률 문제와 규정 준수는 상대적으로 덜 논의되고 있었다. 요구사항과 관련해서는, 클라우드 서비스 공급자 간의 신뢰와 평판이 가장 광범위하게 연구되었으며, 신뢰와 평판은 성공적인 클라우드 연합 구성에 중요한 요소로 강조하였다. 또한, 클라우드 연합의 안정성은, 문헌 검토에서 클라우드 연합 구성을 위한 중요한 과제로 드러났으며, 가장 많이 사용된 연구 동향은, 게임이론(game theory)과 집합이론(set theory)으로, 주로 알고리즘적 접근과 수학적 모델을 중심의 해결책이 제안되었다.
두번째 연구에서는, 6개 연구 질문 중 2개를 다루기 위해 기관 품질 인식 신뢰 클라우드 연합 형성 접근법(institutional quality-aware trusted cloud federation formation approaches)을 제시하였다. 이 혁신적인 접근법은 2단계 신뢰 평가 과정(two-stage trust evaluation process)을 활용하는데, 첫번째 단계에서는 CSP신뢰와 기관 신뢰를 계산하여, CSP 전체 신뢰를 결정하였다. 이어서 두번째 단계에서는 CSP와 사용자로부터의 직접적, 간접적 피드백을 통해 신뢰를 집계하였다. 피드백 집계에 신뢰도 점수를 포함시킴으로써, 이 접근 방법은 거짓 긍정과 거짓 부정의 위험을 효과적으로 줄일 수 있었다. 제안된 모델은 두가지 실험을 통해 평가되어, 신뢰할 수 있는 연합 파트너를 확인하는데 효과적임을 입증하였다. 이러한 연구 결과는, 클라우드 연합 형성에 있어, 신뢰 인식 접근법의 중요성을 강조하고, 멀티 클라우드 전략(multi-cloud strategy)의 신뢰성과 성공확률을 높이는데 가치 있는 통찰력을 제시하였다. 나아가, 본 연구는 클라우드 서비스 공급자 간의 협업 촉진에 기여할 수 있으며, 중소규모 클라우드 서비스 공급자가 클라우드 컴퓨팅 시장의 지배적인 공급자와 효과적으로 경쟁할 수 있도록 기회를 제공하였다.

다국어 초록 (Multilingual Abstract)

Cloud computing is a rapidly growing industry offering numerous benefits to customers, including access to emerging technologies, innovation, and scalability. However, the market is largely dominated by a few major players, limiting the competitiveness of small and medium-sized cloud providers. To effectively compete, small and medium-sized cloud providers need to adopt a multi-cloud strategy, utilizing multiple cloud providers for different purposes. One way to implement a multi-cloud strategy is through cloud federation, which allows cloud providers to buy and sell services from other providers on demand to increase reliability, reduce cost and energy consumption, and provide easy scaling up of resources. This dissertation presents a compelling and comprehensive investigation into the critical phase of cloud federation formation, encompassing two essential studies. The first study conducts a systematic literature review to explore the enabling factors, requirements, challenges, and current trends in cloud federation formation. This review serves as a strong foundation for the subsequent study, which proposes an innovative Institutional Quality-Aware Trusted Cloud Federation Formation approach. The Institutional Quality-Aware Trusted Cloud Federation Formation method is designed to address the complexities and uncertainties involved in forming cloud federations. A novel cloud federation overall architecture and a novel cloud federation formation algorithm is introduced, while also emphasizing a two-stage trust evaluation process for cloud service providers to select reliable partners.
In this study, six research questions were formulated to investigate cloud federation formation comprehensively. The systematic literature review addressed the first four research questions and successfully identified 16 enabling factors, 17 requirements, and 18 major challenges related to cloud federation formation. Among the enabling factors, resource provisioning and flexibility emerged as the most extensively discussed, while legal issues and regulatory compliance were relatively underexplored.
Regarding requirements, trust and reputation among cloud service providers were the most extensively studied, emphasizing their significance in forming successful cloud federations. Additionally, cloud federation stability emerged as a prominent challenge that received substantial attention in the reviewed studies. Notably, the most commonly used research trends were game theory and set theory, and the proposed solutions predominantly revolved around algorithmic approaches and mathematical models.
The second study aimed to address the last two research questions and presented institutional quality-aware trusted cloud federation formation approaches. This innovative approach utilized a two-stage trust evaluation process. The first stage involved computing cloud service provider trust and institutional trust to determine the cloud service provider's global trust. In the second stage, trust was aggregated based on direct and indirect feedback from cloud service providers and users. By incorporating a confidence score for feedback aggregation, the approach effectively mitigated the risks of false positive and false negative feedback. The proposed model was subjected to evaluation through two experiments, demonstrating its effectiveness in identifying trusted potential partners for forming a coalition based on trust. These findings highlight the importance of trust-aware approaches in cloud federation formation and contribute valuable insights to enhance the reliability and success of multi-cloud strategies. Furthermore, the research provides a solid basis for fostering collaboration between cloud service providers and enables small and medium-sized providers to effectively compete with dominant players in the cloud computing market.

목차 (Table of Contents)

• Table of Contents
• Abstract I
• List of Figures X
• List of Tables XIII
• List of Abbreviations XV
• Chapter 1. Introduction 1
• 1.1. Background and Motivation 1
• 1.2. Problem Statement 8
• 1.3. Research Objectives and Questions 12
• 1.4. Research Methodology 15
• 1.5. Significance of the Study 16
• 1.6. Research Contribution 21
• 1.6. Research Outline and Design 24
• Chapter 2. Literature review 26
• 2.1. Cloud Computing 26
• 2.2. Cloud Federation 28
• 2.3. Cloud Federation Lifecycle 32
• 2.3.1. Formation Phase 33
• 2.3.2. Operation and Management Phase 34
• 2.3.3. Evaluation Phase 35
• 2.3.4. Termination Phase 36
• 2.4. Why Cloud Federation Formation 36
• 2.5. Cloud Federation in Practical Perspectives 39
• 2.5.1. ARISTOTLE Cloud Federation 41
• 2.5.2. BEACON (Enabling Federated Cloud Networking) 42
• 2.5.3. Data Federations (Cloud federation use case) 42
• 2.5.4. Federated Learning (Cloud Federation use case) 44
• 2.6. Cloud Federation in Policy Perspective 46
• 2.6.1. Data Privacy and Protection 46
• 2.6.2. Security and Compliance 47
• 2.6.3. Interoperability and Standards 47
• 2.6.4. Governance and Accountability 48
• 2.6.5. Cross-Border Data Transfer 48
• 2.7. Cloud Federation in Theoretical Perspective 49
• 2.7.1. Distributed System and Virtualization 49
• 2.7.2. Resource Management and Allocation 50
• 2.7.3. Interoperability and Standardization 50
• 2.7.4. Trust, Security, and Privacy 51
• 2.7.5. Economic and Business Models 51
• 2.7.6. Performance Evaluation and Optimization 52
• Chapter 3. Enabling Factors, Requirements, Challenges, and Trend Analysis of Cloud Federation Formation using Systematic Literature Review 58
• 3.1. Introduction 58
• 3.1.1. Cloud Federation Formation 60
• 3.1.2. Lack of Existing Review 61
• 3.1.3. Goal and Contribution 62
• 3.2. State of the Art 65
• 3.2.1. Overview 65
• 3.2.2. Comparison of existing review research for identifying the research gap 69
• 3.3. Methodology 74
• 3.3.1. Planning 76
• 3.3.2. Selection 77
• 3.3.3. Data Extraction 81
• 3.4. Analysis 81
• 3.4.1. Descriptive Analysis 82
• 3.4.2. Cloud Federation Formation Enabling (Driving) Factors 85
• 3.4.3. Cloud Provider's Requirements for Establishing Cloud Federation 92
• 3.4.4. Addressed Cloud Federation Formation Challenges 99
• 3.4.5. Existing Trends of Cloud Federation Formation 105
• 3.5. Discussion and Implication of the Findings 119
• 3.5.1. Implications related to Cloud Federation Formation Enabling factors 122
• 3.5.2. Implication related to Cloud Federation Formation requirements 124
• 3.5.3. Implication related to Cloud Federation Formation challenges 126
• 3.5.4. Implication related to current trends 128
• 3.6. Conclusion 130
• 3.6.1. Summary 130
• 3.6.2. Limitation 133
• Chapter 4. Institutional Quality Aware Trusted Cross-Border Cloud Federation Formation 135
• 4.1. Introduction 135
• 4.1.1. Motivation 135
• 4.1.2. Relevance of study 137
• 4.2. State-of-the-art 140
• 4.2.1. Trust Overview 140
• 4.2.2. Identification of Gaps and Problem Formulation 150
• 4.3. Proposed Trusted Cloud Federation Formation Model 159
• 4.3.1. Architectural Overview and overall process (System Architecture) 159
• 4.3.2. Institutional Quality Aware-Trust-based Cloud Federation Formation 164
• 4.3.3. Trust Evaluation Models 179
• 4.4. Experiment 207
• 4.4.1. Initial Trust Evaluation (Experiment 1) 207
• 4.4.2. Trust Evaluation Based on Evidence (Experiment 2) 223
• 4.5. Discussions and Implications 242
• 4.5.1. Discussions 242
• 4.5.2. Implications 248
• Chapter 5. Conclusion 252
• 5.1. Summary 252
• 5.2. Policy Implication 254
• 5.3. Limitation and Future Research 256
• Bibliography 260
• Appendix 1 329
• Acknowledgments 342
• Abstract (Korean) 343

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