Isao Kaji

Assuring interoperability between heterogeneous multi-agent systems with a gateway agent

In this research, we address the problem of a lack of communications between heterogeneous multi-agent systems. For example, the KQML-based agent cannot talk to the FIPA-based agent and vice versa. We have identified three main reasons why different multi-agent systems are not interoperable, which we call architectural elements: (1) inconsistent mental state structures; (2) different syntax and semantics of the agent communication languages; and (3) incompatible message transport mechanisms. To solve this problem, we propose a gateway agent as a translator of the agent communications that assures the integration of heterogeneous multi-agent systems. We have developed a prototype of the gateway agent that can translate messages between the KQML agent and FIPA agent. Based on the results, we are studying a higher level of interoperability based on conversation protocols between agents.

Autonomous data synchronization in heterogeneous systems to assure the transaction

Many companies have been forced to quickly respond to changing user needs. To provide more convenient services to consumers, the cooperation within a company or across companies have been requested. As a result, the heterogeneous information systems are also requested to be integrated together. By utilizing the heterogeneity among systems and by cooperating between systems, it becomes possible to draw out new values from them without violating each systems characteristic. In the heterogeneous systems, such as the data generation timings or frequencies are different, the data synchronization itself should be done by each system without relying on the single coordinator, because the system configurations are always changing, and members of application group which use synchronous data combination are also changing. In this paper we propose the autonomous data synchronization technique in the heterogeneous systems. The application objects which requires the synchronous combination of the data in each system can locally judge which combination of data is most adequate as the synchronous combination by comparing the synchronous information with others. Thus all systems can use the consistent combination as the synchronous data only by collecting the data locally and exchanging the synchronous information. In addition, the cost of synchronization in each system, which is measured by the synchronization waiting time (SWT) and backward data utilization (BDU) becomes even. As this proposed method is not relying on the single coordinator, it works correctly even if the system configuration is dynamically changed, or even if members of SyncApps are changed. The simulation results show the cost fairness when three systems are interconnected in straight line.

Distribution Algorithm for Newly Allocated Update Allowance (AV) in the Autonomous Decentralized Database System(ADDS)

The autonomous decentralized database system (ADDS) was proposed to flexibly cope with companys requirements in dynamically changing environments. In the ADDS each node holds a copy of database, and update requests to the data items in a node can be processed independent of other nodes if the requested amounts are less than the allowances that are called the allowance volume (AV). Many researches have been done regarding the AV adjustments, coordination among nodes, recovery techniques, reconfiguration techniques, etc, but no work has been reported how to distribute the initial or newly added AV to others. This paper proposes how to distribute the initial or newly added AV to other nodes autonomously and tries to confirm the effectiveness through the simulation works

Considerations on transaction response time and configuration checking in autonomous decentralized DB (ADDS)

In a distributed computing environment, the autonomous decentralized database system (ADDS) has been proposed to avoid the single point of failure. In ADDS, the update operations at each node are autonomously performed without communicating with other nodes if the amount of update requests are within the allowance volume (AV), thus the short response time of the transactions can be realized. Each node starts the AV adjustments when given AV amounts reach the threshold value, and gets the AV from relatively surplus nodes. To communicate with other nodes, there are two types of communications, one is a point to point (P2P) communication and the other is a mobile agent (MA) circulation. This paper discusses the relationship among the message amount, the configuration check frequency and the transaction response time in the P2P communication. We have defined the configuration checking frequency (f) that expresses how frequently a node confirms the configuration per AV request. It is expected that the value f which gives the minimum transaction response may exist. The simulator has been developed to evaluate the relationship and simulations have been performed in various parameters.

Autonomous and proactive adjustment of update allowance in autonomous decentralized database system

The autonomous decentralized DB system (ADDS) has been proposed to avoid the single point of failure (SPOF), where the databases are replicated among distributed subsystem nodes, and update operations to the numerical values of the DBs are independently performed at subsystem nodes within their allowances (called allowance volumes). If the request is within the AV, it will be satisfied immediately, and the transaction will be finished shortly. If a shortage of the AV in a subsystem node happens, each node interchanges its request among neighbored nodes. If the AV surplus nodes are there in the system, they give their surplus AV to the request node. Thus the total AV are autonomously adjusted in the system, but the requesting node must wait for the AV satisfied. The arrival rates of the update requests to the subsystems are various, so some nodes consume the AV fast, some nodes slowly. Once the AV shortage condition happens in the system, the response time for that node becomes long. No research work for the proactive AV adjustment has been reported, thus the authors propose to proactively and autonomously adjust the AV in the system in order to balance the AV among the nodes and to lessen the number of the AV shortage nodes as possible.

Autonomous data consistency technique through fair evaluation among heterogeneous systems

By integrating heterogeneous systems with different individual requirements, it becomes possible for application systems to use the various data generated in the heterogeneous systems. Integrated systems also make it possible to process the applications from different points of view and to obtain higher assurance levels. The important requirements for the integration of application systems are not to halt the entire systems, not to violate individual system missions and to derive a synergetic effect. The autonomous decentralized system (ADS), by its online property, enables the integration of systems without stopping any system and without violating any systems mission. To collect consistent data combinations from different systems each subsystem needs to determine the combination independently and autonomously. This paper proposes a new concept, the data alliance, to determine consistent data combination from heterogeneous systems. In addition, the fairness must be maintained between the subsystems to achieve the consistency to satisfy the nature of the autonomous coordinability. This paper defines the fairness among systems in terms of the cost of the data freshness and the alliance waiting time. The data freshness value expresses the degree of how recent the data combination is for the subsystem, and the alliance waiting time expresses how long the subsystem must wait to get agreement among cooperating applications. The last part of the paper shows by simulation that the proposed technique is effective in different system topologies.