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Electric power consumed by servers has to be reduced in order to realize green societies. We consider computation ({\it{CP}}) and storage ({\it{ST}}) types of application processes performed on servers in this paper, where CPU and storage drives are mainly used, respectively. In the storage and computation based power consumption (SCBPC) model proposed by the authors, the power consumption rate of...
It is critical to discuss how to realize not only energy-aware but also robust clusters of servers. A client usually issues a request to one server in a cluster and the server sends a reply to the client. Once the server stops by fault, the client does not receive a reply of the request and might be suspended to wait for a reply. Hence, each request is redundantly performed on multiple servers to...
We discuss how to efficiently and consistently manipulate multiple replicas of a multimedia object. Multimedia replicas are characterized in terms of not only data structure but also quality of service (QoS). Multimedia replicas are written in enriching and impoverishing types of write operations where some data is added and removed in a replica, respectively. Computation resources are spent to materialize,...
Nowadays information systems are being shifted to distributed architectures, i.e. Grid and P2P models to obtain the benefits like scalability, autonomy, and fault-tolerance. We consider the peer-to-peer (P2P) model as a fully distributed, scalable system, which is composed of peer processes (peers). A group of multiple peers cooperate with each other. Here, peers have to efficiently and flexibly deliver...
In order to realize digital ecosystems, the total electric power consumption of computers and networks have to be reduced. In distributed systems, clients issue requests to servers and then servers send replies to clients. Here, application processes are composed of a pair of modules which mainly consume computation and communication resources, respectively. Based on the measurement of the power consumption...
Information systems are composed of various types of computers interconnected in networks. In addition, information systems are being shifted from the traditional client-server model to the peer-to-peer (P2P) model. P2P systems are scalable and fully distributed without any centralized coordinator. Here, it is getting more significant to discuss how to reduce the total electric power consumption of...
In peer-to-peer (P2P) applications, a scalable group of multiple peer processes (peers) are required to cooperate with each other. In this paper, we discuss a two-layered heterogeneous hybrid time (THHT) protocol which takes advantage of the linear time (LT) and physical time (PT) to causally order messages in a scalable heterogeneous group. In a heterogeneous type of group, the clock accuracy of...
Peer-to-peer (P2P) systems are in nature fully distributed with no centralized coordinator. A peer ps has to collect correct object information from trustworthy acquaintances which are considered to hold correct information. We consider two types of trustworthiness. First, the subjective trustworthiness stst on an acquaintance pt shows how much the peer ps trusts the acquaintance pt. The objective...
In information system, it is critical to reduce the total electrical power consumption. We have discussed a power consumption model for communication-based applications. Then, we have proposed a pair of PCB (power consumption-based) and TRB (transmission rate-based) algorithms to select a server so that the total power consumption of the servers is reduced. In addition, we showed the PCB algorithm...
In peer-to-peer (P2P) applications, a group of multiple peer processes (peers) are required to cooperate with each other. In this paper, we discuss a heterogeneous hybrid time group communication (HHT) protocol which takes advantage of the linear time (LT) and physical time (PT) to causally order messages in a scalable heterogeneous group. It depends on accuracy of each physical clock and minimum...
The peer-to-peer (P2P) model is a fully distributed system which is composed of peer processes (peers) which cooperate with each other to achieve a common goal. Here, peers have to efficiently and flexibly make an agreement on one common value which satisfies an agreement condition. We discuss a novel approach to efficiently making an agreement where each peer sends a package of multiple possible...
Information systems are composed of various types of computers interconnected in networks. In addition, information systems are being shifted from the traditional client server model to the peer-to-peer (P2P) model. The P2P systems are scalable and fully distributed without centralized coordinators. It is getting more significant to discuss how to reduce the total electric power consumption of computers...
In various types of peer-to-peer (P2P) applications, peers have to efficiently and flexibly make an agreement on one value which satisfies an agreement condition. In traditional agreement protocols, each peer sends one value to the other peers at each round. If each peer could not make an agreement on the values, the peer sends another value to the other peers at next round. Depending on the order...
In various types of peer-to-peer (P2P) applications, peers have to so efficiently and flexibly make an agreement on one opinion that the peers can change their opinions according to the others. We discuss a flexible agreement protocol of multiple peers in a fully unstructured P2P network. In order to efficiently make an agreement, we discuss a novel approach that each peer sends a package of possible...
Information systems are composed of various types of computers interconnected in types of networks like wireless networks. In addition, information systems are being shifted from the traditional client-server model to the peer-to-peer (P2P) model. The P2P systems are composed of peer processes (peers). They are scalable and fully distributed without centralized coordinators. It is getting more significant...
Energy efficiency has become a very important issue to reduce the consumption of resources on the Earth. We have to consider how to save the energy consumption anywhere and anytime, including a large set of servers, for example, servers in the Google company. Hence, power and energy consumption has recently become key concerns, especially huge number of servers are deployed in large cluster configurations...
In a peer-to-peer (P2P) overlay network, a peer process (peer) communicates with other peers and manipulates objects in local and remote peers. In a fully distributed, unstructured P2P network, there is no centralized coordinator like index and super peer. Each peer has to communicate with its acquaintance peers and obtain service information of other peers. It is critical for a peer to identify which...
In peer-to-peer (P2P) applications, peers make an agreement on one opinion. Agreement procedures have to be so flexible that persons can change their opinions. We discuss a flexible agreement protocol of multiple peers by taking advantage of human behaviors in a fully unstructured P2P network. There are forward, backward, mining, and observation strategies for each peer to find a value to make an...
In peer-to-peer (P2P) applications, peers make an agreement on one opinion. Agreement procedures have to be so flexible that persons can change their opinions. We discuss a flexible agreement protocol of multiple peers by taking advantage of human behaviors in a fully unstructured P2P network. There are forward, backward, mining, and observation strategies for each peer to find a value to make an...
In peer-to-peer (P2P) applications, peers exchange their opinions with each other and make an agreement on one opinion. Agreement procedures have to be so flexible that persons can change their opinions, withdraw previous opinions under some constraints on the opinions, and use various types of agreement conditions like majority-condition in our society. We discuss a flexible agreement protocol of...
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