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The evolving intercloud enables idle resources to be traded among cloud providers to facilitate utilization optimization and to improve the cost-effectiveness of the service for cloud consumers. However, several challenges are raised for this multi-tier dynamic market, in which cloud providers not only compete for consumer requests but also cooperate with each other. To establish a healthier and more efficient intercloud ecosystem, in this paper a multi-tier agent-based fuzzy constraint-directed negotiation (AFCN) model for a fully distributed negotiation environment without a broker to coordinate the negotiation process is proposed. The novelty of AFCN is the use of a fuzzy membership function to represent imprecise preferences of the agent, which not only reveals the opponent’s behavior preference but can also specify the possibilities prescribing the extent to which the feasible solutions are suitable for the agent’s behavior. Moreover, this information can guide each tier of negotiation to generate a more favorable proposal. Thus, the multi-tier AFCN can improve the negotiation performance and the integrated solution capacity in the intercloud. The experimental results demonstrate that the proposed multi-tier AFCN model outperforms other agent negotiation models and demonstrates the efficiency and scalability of the intercloud in terms of the level of satisfaction, the ratio of successful negotiation, the average revenue of the cloud provider, and the buying price of the unit cloud resource.

An independent component recovery approach for intrusion tolerance is proposed in this paper. Virtual Machines (VMs) are used to provide each online replica with an independent backup replica. The recovery of each component depends on the actual service state. A strict execution order is not needed to create VMs, destroy VMs and synchronize state data. The approach improves the flexibility of components of the system. In addition, for preventing the state data from losing during the recovery of replicas, a set of virtual storages, which can be connected or disconnected with online servers quickly, are used for storing the state data. A fixed cycle is set for synchronizing the state data independently. A prototype is implemented in the OpenStack cloud platform. Experimental results show that the approach improves the continuity and security of the services.