[show abstract][hide abstract] ABSTRACT: Peer-to-peer (P2P) communication and computing frame-works are important for constructing robust large-scale distributed sys-tems. Overlay network systems use distributed hash-table (DHT) to pro-vide scalable and efficient node search capabilities. However, the DHT-based method has a problem for the maintenance cost of dynamically changing large-scale-network, in which nodes are frequently joining and leaving. This paper proposes a novel technique of P2P communication path management. The proposed technique devises a robust semi-structured overlay network called Ordered Tree with Tuft (OTT for short). OTT provides not only efficient node searching, but also low-cost self-maintenance capabilities for the dynamically changing network. In this method, join-ing and leaving of a node are managed in O(1) with high probability. Furthermore, the proposed OTT-based technique can find and construct a path shorter than that on the normal ordered tree, by setting up bypass links between remote nodes on OTT.
[show abstract][hide abstract] ABSTRACT: Current trend of research on multithreading processors is toward the chip multithreading (CMT), which exploits thread level
parallelism (TLP) and improves performance of softwares built on traditional threading components, e.g., Pthread. There exist
commercially available processors that support simultaneous multithreading (SMT) on multicore processors. But they are basically
based on the conventional sequential execution model, and execute multiple threads in parallel under the control of OS that
handles interruptions. Moreover, there exist few languages or programming techniques to utilize the multicore processors effectively.
We are taking another approach to develop a multithreading processor, which is dedicated to TLP. Our processor, named Fuce, is based on the continuation-based multithreading. A thread is defined as a block of sequentially ordered instructions which
are executed without interruption. Every thread execution is triggered only by the event called continuation.
This paper first introduces the continuation-based multithread execution model and its processor architecture then gives multithreaded
programming techniques and the continuation-based multithreading language system CML. Last, the performance of the Fuce processor is evaluated by means of the clock-level software simulation.
The Journal of Supercomputing 01/2009; 47:228-252. · 0.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Community-based collaboration support systems are useful for exchanging information on topics that community members are interested
in. Most of them developed so far are based on server-client architecture and provide their services on Web servers. They
require special administrative facilities, and ask users to upload their data on the systems. Furthermore, security mechanisms
are not often provided for the communities. Considering these problems, we have been developing an Agent-Community-Network-based
collaboration support system: in particular, a business-matching support system. Our system requires neither any special administrative
facilities nor the need to upload user data to a special server. Furthermore, it supports secure peer-to-peer communication
between users. It is implemented with a multi-agent Kodama framework.
[show abstract][hide abstract] ABSTRACT: Business matching and collaboration support systems are useful, in particular for small-and-medium sized companies. Most of them developed so far are based on the server-client architecture and provide their services on Web servers. They require special administrative facilities, ask users to upload their data for matching between business needs and seeds, and leave to themselves peer-to-peer communication or ne- gotiation between matched companies. Considering these problems, we have been developing an agent-community- network-based business matching and collaboration support system. Our system requires neither any special adminis- trative facilities nor uploading user data to a special server. It furthermore supports secure peer-to-peer communication between users. It is implemented with multi-agent Kodama framework.
7th International Joint Conference on Autonomous Agents and Multiagent Systems (AAMAS 2008), Estoril, Portugal, May 12-16, 2008, Industry and Applications Track Proceedings; 01/2008
[show abstract][hide abstract] ABSTRACT: Current trends of research on multithreading processors are the chip multithreading (CMT), which aims to exploit thread level parallelism (TLP) and to improve performance of software built onalltraditional threading components, e.g. pthreads. However, CMT is principally a straight forward extension of conventionalall symmetric multiprocessor (SMP) techniques, and it will suffer from the same limits to scalable multithreaded processing ifallit is built only on the traditional sequential-computation-based framework. Consideringallthese limitations of sequential-processor-basedallmultithreading, we are taking another approach to developing a multithreading processor dedicated to thread level parallelism(TLP). Our processor, named Fuce, is based on continuation-based multithreading. A thread is defined as a block of sequentially ordered instructions which areall executed exclusively. Every execution of a thread is triggered by one or more events, each of which is called continuation. The hardware cost and performance of the Fuce processor areallevaluated by means of a hardware implementation on FPGA and software simulation.
Proceedings of the 4th Conference on Computing Frontiers, 2007, Ischia, Italy, May 7-9, 2007; 01/2007
[show abstract][hide abstract] ABSTRACT: Multi-tasking operating systems not only handle concurrent tasksbut also have concurrency and parallelism of various granularities in themselves. We claim that operating systems need to be developed based on a computation model that can deal with concurrency and parallelism of various granularities. In order to investigate this claim, we have been developing an operating system called CEFOS based on a dataflow-based computation model. A program for CEFOS consists of zero-waitthreads, each of which runs to completion without suspension once started. Synchronization between zero-wait threads is performed in a dataflow manner according to their continuation relations. Handler routines for I/O devices are also realized with zero-wait threads and executed under the continuation-based multithreading mechanism. We can eliminate "interrupts" that interfere with the execution ofinstruction streams in typical conventional approaches, and we can naturally handle concurrency and exploit parallelism in programs even for I/O-centric computation. In this paper, after introducing our model and our operating system based on the model, we discuss implementation issues on Fuce, which is a continuation-based multithreading processor dedicated to fine-grained multithreading. Then we evaluate the scalability of our system with the number of execution units and I/O devices.
Proceedings of the 4th Conference on Computing Frontiers, 2007, Ischia, Italy, May 7-9, 2007; 01/2007
[show abstract][hide abstract] ABSTRACT: Fine-grained multithreading based on a natural model, such as dataflow model, is promising in achieving high efficiency and high programming productivity. In this paper, we discuss operating system issues for fine-grained multithread programs. We are developing an operating system called CEFOS based on a dataflow based computation model. A program on CEFOS consists of zero-wait threads which run to completion without suspension once started. Firing control among such threads is performed in a dataflow manner along with continuation relations in the program. Target platforms include Fuce processor, which is dedicated to fine-grained multithreading, and commodity processors such as Intel x86. In this paper, after introducing our basic model and our operating system model, we discuss implementation issues on Fuce and commodity platforms. The evaluation results indicate that our approach on commodity platforms is effective in reducing overheads while our approach on a special architecture naturally exploit parallelism even in I/O handling.
Parallel and Distributed Processing Symposium, International. 01/2007;
[show abstract][hide abstract] ABSTRACT: Nowadays, development of processors which support concurrent multi-thread execution is becoming a trend. Most of these processors are aimed at exploiting instruc- tion level parallelism (ILP). But many researchers feel that the limits of ILP exploitation are rapidly being reached. In addition, exploiting more ILP makes the circuitry of proces- sor very complicated. We are taking another simpler ap- proach, and developing a processor focused only on thread level parallelism (TLP). Our processor is named Fuce. it is based on the continuation model which is derived from the dataflow computing model. In this paper, we introduce the core concepts of Fuce, the programming model for Fuce and an overview of Fuce architecture. We also show simu- lation results.
Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Applications & Conference on Real-Time Computing Systems and Applications, PDPTA 2006, Las Vegas, Nevada, USA, June 26-29, 2006, Volume 1; 01/2006
[show abstract][hide abstract] ABSTRACT: In the near future, people will be able to access information and resources on the public open network environment. However, few current network environments seem to have unified method for protection of information and resource. This paper proposes a unified resource protection scheme on the basis of fusion of two multi-agent systems called Kodama and VPC. Kodama has the power of constructing flexible hierarchical logical spaces, and VPC has the ability to dynamically change its behavior according to the circumstance of user. As a protection scheme, two kinds of policies called public policy and private policy are introduced into the fused multi-agent system. Combination of these policies makes it possible to realize an open and secure information sharing system. We show practical sample applications using the scheme.
Information Technology and Applications, 2005. ICITA 2005. Third International Conference on; 08/2005
[show abstract][hide abstract] ABSTRACT: Grid computing is promissing as an infrastructure that allows users to use distributed computer resources by simple connecting
a computer to the network without special operation; just like connecting to the electricity, water or gas grid. In this paper,
regarding resources as services, we propose a new architecture for realizing an environment in which users can use services
that are in various locations through their portable terminals. In this architecture, a service is managed by an agent, which has two resource management spaces named the Public Zone and the Private Zone. The Public Zone is a space for realizing flexible public service use. The Private Zone is a space for protecting private
user information. Moreover, agents are organized in a group called the community and are managed independently in each community. Thus, we realize both of flexible service use while protecting private information.
[show abstract][hide abstract] ABSTRACT: We are developing the Fuce processor based on the dataflow computing model. Fuce means fusion of communication and execution. In order to execute many threads with multiple thread execution units efficiently, the Fuce processor executes multiple threads using the exclusive multi-thread execution model. The core concept of the exclusive multi-thread execution model is continuation based multi-thread execution, which is derived from dataflow computing. The Fuce processor aims to fuse the intra-processor execution and inter-processor communication. The Fuce processor unifies processing inside the processor and communication with processors outside as events, and executes the event as a thread. In this paper, we introduce the architecture of the Fuce processor and evaluate the concurrency performance of a Fuce processor which we described in VHDL. As a result, we understood that the processor has concurrency capability when there is sufficient thread level parallelism.
Innovative Architecture for Future Generation High-Performance Processors and Systems, 2005; 02/2005
[show abstract][hide abstract] ABSTRACT: Agent technology is ready to shift from the stage in which agent architectures are proposed to the stage in which applications
working in the real world are developed. Accordingly, we have developed an agent-based application integrating VPC and KODAMA,
as an example of a system where agents can behave effectively in the real world. VPC on KODAMA is a framework for actualizing
a ubiquitous computing environment. VPC on KODAMA has a mechanism that assigns services to user agents according to their
profiles. Using VPC on KODAMA, we developed an information notification system. This system sends advertisement e-mail tailored
to user profiles, including user location, to the user’s cellular phone. We have conducted a large-scale experiment in shopping
malls. The results of this experiment show that agent technology is effective for applications in ubiquitous computing environments.
[show abstract][hide abstract] ABSTRACT: Recently, agent technologies have attracted a lot of interest as an
emerging programming paradigm. With such agent technologies, services
are provided through collaboration among agents. At the same time, the
spread of mobile technologies and communication infrastructures has made
it possible to access the network anytime and from anywhere. Using
agents and mobile technologies to realize ubiquitous computing systems,
we propose a new framework based on KODAMA and VPC. KODAMA provides
distributed management mechanisms by using the concept of community and
communication infrastructure to deliver messages among agents without
agents being aware of the physical network. VPC provides a method of
defining peer-to-peer services based on agent communication with policy
By merging the characteristics of both KODAMA and VPC
functions, we propose a new framework for ubiquitous computing
environments. It provides distributed management functions according to
the concept of agent communities, agent communications which are
abstracted from the physical environment, and agent collaboration with
Using our new framework, we conducted a
large-scale experiment in shopping malls in Nagoya, which sent
advertisement e-mails to users' cellular phones according to user
location and attributes. The empirical results showed that our new
framework worked effectively for sales in shopping malls.
Transactions of the Japanese Society for Artificial Intelligence 01/2004; 19:300-310.
[show abstract][hide abstract] ABSTRACT: The KODAMA methodology is our endeavour to explore new analysis and design methodologies, as well as new tools, for developing
ubiquitous applications around autonomous, interacting software agents. To concrete and detail the well-known multiagent system
paradigm, KODAMA introduces a plug-and-play agent model, an agent community model and an on-demand interaction model. At the
top level, a whole system is decomposed into various agent communities. Working one level down, communities are broken down
into independent agents. At the lowest level, agent roles are the basic entities for specifying agent activities in online
interactions. In this article, we first present how these new models are exploited in the analysis and design phases; then
discuss some details of how they are implemented in a practical shopping-support system.
Embedded Software and Systems, First International Conference, ICESS 2004, Hangzhou, China, December 9-10, 2004, Revised Selected Papers; 01/2004
[show abstract][hide abstract] ABSTRACT: Next generation of information systems will rely on cooperative intelligent agents for playing a fundamental role in actively searching and finding relevant information on behalf of their users in complex and open environments, such as the Internet. User interface agents (UIA) are semi-intelligent systems, which help the users to access, manage, share and exchange information. Recently, various researchers have proposed a learning approach towards building such agents and some working prototypes have been demonstrated. Such agents learn by watching over the shoulder of the user and detect patterns and regularities in the user's behavior. We present a new approach of the collaborative UIA that helps the user to retrieve information that is consistent to the user's need. The model provides tools and utilities for the user to manage his/her information repositories with dynamic organization and adaptation views. In order to investigate the performance of the UIA, we carried out several experiments. Through the experiments, the results ensure that the techniques of personalization, clustering the user's preferences, and making use of the preferences promise to achieve more relevant information to the user's queries.
[show abstract][hide abstract] ABSTRACT: Mobile devices and wireless network infrastructures will be leading users to seamlessly use peer-to-peer services and ubiquitous computing by the growing of the infrastructures. In order to realize to use peer-to-peer services and ubiquitous services seamlessly, a new framework that enables users to use peer-to-peer services and ubiquitous computing is required. Hence, this paper describes a new ubiquitous computing framework, called VPC on KODAMA, using a peer-to-peer mechanism. Virtual Private Community (VPC) is an execution environment for peer-to-peer services, and provides a framework for definition of peer-to-peer services. Peer-to-peer services in VPC are defined as policy packages that have necessary elements to provide the services. Peer-to-peer services are offered in communities by collaboration among roles that are assigned to users. KODMA provides a network infrastructure for agents. Agents in KODAMA have their own community, and represent the communities. Communities have a hierarchy structure by agents residing in other agent's communities. Agents have message filtering policy, and refuse messages that are against the policy. By unifying VPC and KODAMA, a new framework that enables services to define roles and their behavior and to manage logical relationship among communities is provided. VPC on KODAMA enables users to use peer-to-peer services and appliances seamlessly with their mobile devices.
Distributed Computing Systems, 2003. FTDCS 2003. Proceedings. The Ninth IEEE Workshop on Future Trends of; 06/2003