Cloud computing has been a hot topic in the research community since 2007. In cloud computing the online services are conducted to be pay as you use. Services need not to be in a long term contract with service providers. Service level agreements (SLAs) are agreements signed between a service provider and other party like a service consumer, broker agent, or monitoring agent. Because cloud computing is recent technology providing many services for critical business applications, the need for reliable and flexible mechanisms to manage online contracts is very important. This paper presents the main criteria which should be considered at the stage of designing SLA in cloud computing. Also, we investigate the negotiation strategies between cloud provider and cloud consumer and propose our method to maintain the trust and reliability between each party which is involved in the negotiation processes.

Cloud computing is a new form of technology, which infrastructure, developing platform, software, and storage can be delivered as a service in a pay as you use cost model. However, for critical business application and more sensitive information, cloud providers must be selected based on high level of trustworthiness. In this paper, we present a trust model to evaluate cloud services in order to help cloud users select the most reliable resources. We integrate our previous work "conceptual SLA framework for cloud computing" with the proposed trust management model to present a new solution of defining the reliable criteria for the selection process of cloud providers.

Abstract-Cloud services are becoming popular in terms of distributed technology because they allow cloud users to rent well-specified resources of computing, network, and storage infrastructure. Users pay for their use of services without needing to spend massive amounts for integration, maintenance, or management of the IT infrastructure. Before interaction occurs between cloud providers and users, trust in the cloud relationship is very important to minimize the security risk and malicious attacks. The notion of trust involves several dimensions. These dimensions include: the scalability, availability, security, and usability parameters of IaaS, PaaS, SaaS, and DaaS. Each of these dimensions is characterized by fuzzy aspects and linguistic terms. This paper develops a model for each of the dimensions for IaaS using fuzzy-set theory. It then uses the sugeno fuzzy-inference approach for developing an overall measure of trust value of the cloud providers. It is not easy to evaluate the cloud metrics for a general domain. So, in this paper, we will use an e-learning application as the main example when we collect the data and apply the fuzzy model to evaluate the trust for cloud computing. Test and results are presented to evaluate the effectiveness and robustness of the proposed model.

Cloud services are becoming popular in terms of distributed technology because they allow cloud users to rent well-specified resources of computing, network, and storage infrastructure. Users pay for their use of services without needing to spend massive amounts for integration, maintenance, or management of the IT infrastructure. This creates the need for a reliable measurement methodology of the scalability for this type of new paradigm of services. In this paper, we develop performance metrics to measure and compare the scalability of the resources of virtualization on the cloud data centres. First, we discuss the need for a reliable method to compare the performance of cloud services among a number of various services being offered. Second, we develop a different type of metrics and propose a suitable methodology to measure the scalability using these types of metrics. We focus on the visualization resources such as CPU, storage disk, and network infrastructure. Finally, we compare well-known cloud providers using the proposed approach and conclude the recommendations. This type of research will help cloud consumers, before signing any official contract to use the desired services, to ascertain the ability and capacity of the cloud providers to deliver a particular service.

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