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Distributed computing paradigms for sharing resources such as Clouds, Grids, Peer-to-Peer systems, or voluntary computing are becoming increasingly popular. While there are some success stories such as PlanetLab, OneLab, BOINC, BitTorrent, and SETI@home, a widespread use of these technologies for business applications has not yet been achieved. In a business environment, mechanisms are needed to provide incentives to potential users for participating in such networks. These mechanisms may range from simple non-monetary access rights, monetary payments to specific policies for sharing. Although a few models for a framework have been discussed (in the general area of a "Grid Economy"), none of these models has yet been realised in practice. This book attempts to fill this gap by discussing the reasons for such limited take-up and exploring incentive mechanisms for resource sharing in distributed systems. The purpose of this book is to identify research challenges in successfully using and deploying resource sharing strategies in open-source and commercial distributed systems.

Inhaltsverzeichnis

Frontmatter

Economic Models and Algorithms for Distributed Systems

Economic Models and Algorithms for Distributed Systems

Modern computing paradigms have frequently adopted concepts from distributed systems. The quest for scalability, reliability and cost reduction has led to the development of massively distributed systems, which extend organisational boundaries. Voluntary computing environments (such as BOINC), Grids (such as EGEE and Globus), and more recently Cloud Computing (both open source and commercial) have established themselves as a range of distributed systems.
Dirk Neumann, Mark Baker, Jörn Altmann, Omer Rana

Reputation Mechanisms and Trust

Frontmatter

A Belief-based Trust Model for Dynamic Service Selection

Provision of services across institutional boundaries has become an active research area. Many such services encode access to computational and data resources (comprising single machines to computational clusters). Such services can also be informational, and integrate different resources within an institution. Consequently, we envision a service rich environment in the future, where service consumers can intelligently decide between which services to select. If interaction between service providers/users is automated, it is necessary for these service clients to be able to automatically chose between a set of equivalent (or similar) services. In such a scenario trust serves as a benchmark to differentiate between service providers. One might therefore prioritize potential cooperative partners based on the established trust. Although many approaches exist in literature about trust between online communities, the exact nature of trust for multi-institutional service sharing remains undefined. Therefore, the concept of trust suffers from an imperfect understanding, a plethora of definitions, and informal use in the literature. We present a formalism for describing trust within multi-institutional service sharing, and provide an implementation of this; enabling the agent to make trust-based decision. We evaluate our formalism through simulation.
Ali Shaikh Ali, Omer F. Rana

Reputation, Pricing and the E-Science Grid

One of the fundamental aspects for an efficient Grid usage is the optimization of resource allocation among the participants. However, this has not yet materialized. Each user is a self-interested participant trying to maximize his utility whereas the utility is not only determined by the fastest completion time, but on the prices as well. Future revenues are influenced by users’ reputation. Reputation mechanisms help to build trust between loosely coupled and geographically distributed participants. Providers need an incentive to reduce selfish cancellation of jobs and privilege own jobs. In this chapter we present first an offline scheduling mechanism with a fixed price. Jobs are collected by a broker and scheduled to machines. The goal of the broker is to balance the load and to maximize the revenue in the network. Consumers can submit their jobs according to their preferences, but taking the incentives of the broker into account. This mechanism does not consider reputation. In a second step a reputation-based pricing mechanism for a simple, but fair pricing of resources is analyzed. In e-Science researchers do not appreciate idiosyncratic pricing strategies and policies. Their interest lies in doing research in an efficient manner. Consequently, in our mechanism the price is tightly coupled to the reputation of a site to guarantee fairness of pricing and facilitate price determination. Furthermore, the price is not the only parameter as completion time plays an important role, when deadlines have to be met. We provide a flexible utility and decision model for every participant and analyze the outcome of our reputation-based pricing system via simulation.
Arun Anandasivam, Dirk Neumann

Trust-oriented Utility-based Community Structure in Multiagent Systems

The problem we address in this chapter is how to design the community structure of a multiagent system in such a way that agents join the communities that will maximize their utility and communities accept the agents that will maximize their utility, towards a stable and productive multiagent system. In order to accomplish this goal, we propose allowing communities to exchange information about the reputability of agents. In particular, it agent a 1 exists in community c 1 and would now like to join c 2, c 2 will ask c 1 for the reputation rating of a 1 and then decide whether to allow the agent to join. Allowing for the sharing of reputation ratings then requires i) a method for determining the truthfulness of the reputation reports ii) an incentive mechanism to encourage the sharing of information iii) some consideration of privacy of information within the system. In order for agents to make effective selection of communities in which to participate, it is also ideal community enjoy and about the tendency for the community to be truthful, when it reports reputation ratings of agents. We present a reputation sharing system that promotes effective community structure, along with examples to demonstrate the benefit of this particular approach.
Georgia Kastidou, Robin Cohen

Formation of Virtual Organizations in Grids: A Game-Theoretic Approach

The execution of large scale grid applications requires the use of several computational resources owned by various Grid Service Providers (GSPs). GSPs must form Virtual Organizations (VOs) to be able to provide the composite resource to these applications. We consider grids as self-organizing systems composed of autonomous, self-interested GSPs that will organize themselves into VOs with every GSP having the objective of maximizing its profit. We formulate the resource composition among GSPs as a coalition formation problem and propose a game-theoretic framework based on cooperation structures to model it. Using this framework, we design a resource management system that supports the VO formation among GSPs in a grid computing system.
Thomas E. Carroll, Daniel Grosu

Towards Dynamic Authentication in the Grid — Secure and Mobile Business Workflows Using GSet

Until now, the research community mainly focused on the technical aspects of Grid computing and neglected commercial issues. However, recently the community tends to accept that the success of the Grid is crucially based on commercial exploitation. In our vision Foster’s and Kesselman’s statement “The Grid is all about sharing.” has to be extended by “... and making money out of it!”. To allow for the realization of this vision the trust-worthyness of the underlying technology needs to be ensured. This can be achieved by the use of gSET (Gridified Secure Electronic Transaction) as a basic technology for trust management and secure accounting in the presented Grid based workflow. We present a framework, conceptually and technically, from the area of the Mobile-Grid, which justifies the Grid infrastructure as a viable platform to enable commercially successful business workflows.
Jürgen Mangler, Erich Schikuta, Christoph Witzany, Oliver Jorns, Irfan Ul Haq, Helmut Wanek

Service Level Agreements

Frontmatter

Enforcing Service Level Agreements Using an Economically Enhanced Resource Manager

Traditional resource management has had as its main objective the optimisation of throughput, based on parameters such as CPU, memory, and network bandwidth. With the appearance of Grid Markets, new variables that determine economic expenditure, benefit and opportunity must be taken into account. The SORMA project aims to allow resource owners and consumers to exploit market mechanisms to sell and buy resources across the Grid. SORMA’s motivation is to achieve efficient resource utilisation by maximising revenue for resource providers, and minimising the cost of resource consumption within a market environment. An overriding factor in Grid markets is the need to ensure that desired Quality of Service levels meet the expectations of market participants. This paper explains the proposed use of an Economically Enhanced Resource Manager (EERM) for resource provisioning based on economic models. In particular, this paper describes techniques used by the EERM to support revenue maximisation across multiple Service Level Agreements.
Mario Macías, Garry Smith, Omer Rana, Jordi Guitart, Jordi Torres

Extended Resource Management Using Client Classification and Economic Enhancements

Commercialization of computing resources will become more and more important as the transition from Grid computing in academic environments to commercial services based on concepts such as utility or Cloud computing progresses. This results in the necessity to not only base components on technical aspects, but also to include economical aspects in their design. This paper presents a framework that links technical and economical aspects to the management of computational resources. Economic enhancements like dynamic pricing and client classification are introduced based on a technical resource management environment and positioned within this resulting in a proposed architecture for an Economically Enhanced Resource Manager (EERM). The introduced approach is evaluated considering various economic design criteria and example scenarios.
Tim Püschel, Nikolay Borissov, Dirk Neumann, Mario Macías, Jordi Guitart, Jordi Torres

Mitigating Provider Uncertainty in Service Provision Contracts

Uncertainty is an inherent property of open, distributed and multiparty systems. The viability of the mutually beneficial relationships which motivate these systems relies on rational decision-making by each constituent party under uncertainty. Service provision in distributed systems is one such relationship. Uncertainty is experienced by the service provider in his ability to deliver a service with selected quality level guarantees due to inherent non-determinism, such as load fluctuations and hardware failures. Statistical estimators utilized to model this non-determinism introduce additional uncertainty through sampling error. Inability of the provider to accurately model and analyze uncertainty in the quality level guarantees can result in the formation of sub-optimal service provision contracts. Emblematic consequences include loss of revenue, inefficient resource utilization and erosion of reputation and consumer trust. We propose a utility model for contract-based service provision to provide a systematic approach to optimal service provision contract formation under uncertainty. Performance prediction methods to enable the derivation of statistical estimators for quality level are introduced, with analysis of their resultant accuracy and cost.
Chris Smith, Aad van Moorsel

Text-Content-Analysis based on the Syntactic Correlations between Ontologies

The work presented in this chapter is concerned with the analysis of semantic knowledge structures, represented in the form of Ontologies, through which Service Level Agreements (SLAs) are enriched with new semantic data. The objective of the enrichment process is to enable SLA negotiation in a way that is much more convenient for a Service Users. For this purpose the deployment of an SLA-Management-System as well as the development of an analyzing procedure for Ontologies is required. This chapter will refer to the BREIN, the FinGrid and the LarKC projects. The analyzing procedure examines the syntactic correlations of several Ontologies whose focus lies in the field of mechanical engineering. A method of analyzing text and content is developed as part of this procedure. In order to so, we introduce a formalism as well as a method for understanding content. The analysis and methods are integrated to an SLA Management System which enables a Service User to interact with the system as a service by negotiating the user requests and including the semantic knowledge. Through negotiation between Service User and Service Provider the analysis procedure considers the user requests by extending the SLAs with semantic knowledge. Through this the economic use of an SLA-Management-System is increased by the enhancement of SLAs with semantic knowledge structures. The main focus of this chapter is the analyzing procedure, respectively the Text-Content-Analysis, which provides the mentioned semantic knowledge structures.
Axel Tenschert, Ioannis Kotsiopoulos, Bastian Koller

Business Models and Market Mechanisms

Frontmatter

Cloud Computing Value Chains: Understanding Businesses and Value Creation in the Cloud

Based on the promising developments in Cloud Computing technologies in recent years, commercial computing resource services (e.g. Amazon EC2) or software-as-a-service offerings (e.g. Salesforce. com) came into existence. However, the relatively weak business exploitation, participation, and adoption of other Cloud Computing services remain the main challenges. The vague value structures seem to be hindering business adoption and the creation of sustainable business models around its technology. Using an extensive analyze of existing Cloud business models, Cloud services, stakeholder relations, market configurations and value structures, this Chapter develops a reference model for value chains in the Cloud. Although this model is theoretically based on porter’s value chain theory, the proposed Cloud value chain model is upgraded to fit the diversity of business service scenarios in the Cloud computing markets. Using this model, different service scenarios are explained. Our findings suggest new services, business opportunities, and policy practices for realizing more adoption and value creation paths in the Cloud.
Ashraf Bany Mohammed, Jörn Altmann, Junseok Hwang

A Model for Determining the Optimal Capacity Investment for Utility Computing

Utility computing has emerged as a new IT model for future computing and storage resource management for enterprises. Utility computing has drawn attention from enterprise customers who seek to reduce upfront IT investment and enhance computing agility. Major IT service providers envisioned that the commoditization and standardization of IT resources would usher in the shift of the IT paradigm towards utility computing. In this paper, a decision model is presented for determining the optimal capacity of a utility computing which maximizes the total profit for a utility computing service provider. The model considers both capacity investment cost and demand level, and derives closed from solutions for the investment.
In Lee

A Combinatorial Exchange for Complex Grid Services

The Grid is a promising concept to solve the dilemma of increasingly complex and demanding applications being confronted with the need for a more efficient and flexible use of existing computer resources. Even though Grid technologies have made progress within the context of large enterprises and academic projects, there has not yet been a widespread adoption by public institutions and small enterprises. One barrier to this adoption is the lack of economic paradigms which support the dynamic and efficient sharing of Grid resources by balancing resource scarity and idle capacities. Economic algorithms promise to provide a good fit to the Grid’s inherent strategic dimension by enabling users to express their valuation for computer resources. At the same time they provide incentives to contribute idle resources to the Grid in return for the market price.
This paper presents a market-based approach for trading complex computational Grid services. The implemented combinatorial exchange aims at maximizing the social welfare of users. At its core, it provides a rich bidding language which is able to represent complex Grid services and simple workflows. The allocation mechanism is evaluated by means of a numerical experiment in order to gain detailed insights into the computational complexity of the underlying allocation problem. Our analysis provides input for the configuration of Grid markets.
Melanie Moßmann, Jochen Stößer, Adam Ouorou, Eric Gourdin, Ruby Krishnaswamy, Dirk Neumann

Heuristic Scheduling in Grid Environments: Reducing the Operational Energy Demand

In a world where more and more businesses seem to trade in an online market, the supply of online services to the ever-growing demand could quickly reach its capacity limits. Online service providers may find themselves maxed out at peak operation levels during high-traffic timeslots but too little demand during low-traffic timeslots, although the latter is becoming less frequent. At this point deciding which user is allocated what level of service becomes essential. The concept of Grid computing could offer a meaningful alternative to conventional super-computing centres. Not only can Grids reach the same computing speeds as some of the fastest supercomputers, but distributed computing harbors a great energy-saving potential. When scheduling projects in such a Grid environment however, simply assigning one process to a system becomes so complex in calculation that schedules are often too late to execute, rendering their optimizations useless. Current schedulers attempt to maximize the utility, given some sort of constraint, often reverting to heuristics. This optimization often comes at the cost of environmental impact, in this case CO 2 emissions. This work proposes an alternate model of energy efficient scheduling while keeping a respectable amount of economic incentives untouched. Using this model, it is possible to reduce the total energy consumed by a Grid environment using ‘just-in-time’ flowtime management, paired with ranking nodes by efficiency.
Christian Bodenstein

Facing Price Risks in Internet-of-Services Markets

Internet-of-Services markets allow companies to procure computational resources and application services externally and thus to save both internal capital expenditures and operational costs. Despite the advantages of this new paradigm only few work has been done in the field of risk management concerning Internet-of-Services markets. We simulate such a market using a Grid simulator. The results show that market participants are exposed to price risk. Based on our results we identify and assess technical failures which could lead to loss on service consumer’s side. We also show that technical failures influence service prices which lead to volatile prices. Both, service provider and service consumer are exposed to this uncertainty and need a way to face it. Therefore we apply a financial option model to overcome price risk.
Raimund Matros, Werner Streitberger, Stefan Koenig, Torsten Eymann
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