Toshibumi Seki

HMS Development and Implementation Environments

In this chapter, desirable features of Holonic Manufacturing System (HMS) development and implementation environments are extracted, and HMS-Shell and JDPS are explained, as examples that provide these features. HMS-Shell is a GUI-based design tool for HMSs based on the Cooperation Domain (CD) that encapsulates cooperation partners and cooperation protocols. JDPS is a HMS implementation and execution environment based on reliable broadcast messaging that achieves complete location and multiplication transparency of entities. These features of HMS-Shell and JDPS make application programs independent of cooperation mechanisms, and enable easy dynamic reconfiguration and incremental development of HMSs while systems are in operation.

Hypersequential programming: a new way to develop concurrent programs

The authors present hypersequential programming, a new method that eases the difficulty of concurrent programming and makes the concurrent program highly reliable. The difficulty of concurrent programming is due mainly to its nondeterminism. The authors classify nondeterminism into three types: intended, harmful, and persistent. In traditional concurrent programming, a programmer first designs and implements programs so as to maximize concurrency, which may include all three types of nondeterminism. She then tries to detect harmful nondeterministic behavior by testing and debugging them. However, removing all harmful nondeterministic behavior is actually very difficult. Hypersequential programming, on the other hand, first serializes the concurrent program to remove all types of nondeterminism, and then the programmer tests and debugs it as a sequential program. Finally, it is parallelized by restoring only intended and persistent nondeterminism. Hypersequential programming can develop a highly reliable concurrent program, because the injection of harmful nondeterminism is precluded. In this article, the authors also present a simple embodiment of hypersequential programming using Petri nets.

Development of Intellectual Distributed Processing System

Abstract The Intellectual Distributed Processing System (IDPS) does not have any centralized managing element. IDPS system elements find their roles autonomously, in order to complete given objectives. IDPS system elements are also able to solve conflicts among different objectives without any supervisory element, by exchanging information among elements. In this paper, fundamental mechanisms for managing system elements distributedly are described. These mechanisms are implemented on the object oriented distributed operating system, which has been developed on multi micro computers connected by local area network. It is expected that large scale adaptive systems can be developed and operated easier by these mechanisms.

Network integrated supervisory control for power systems based on distributed objects

This paper proposes a new architecture called SCOPE (System Configuration Of PowEr control system) for flexible supervisory control of power systems. Energy Management Systems / Supervisory Control and Data Acquisition (EMS/SCADA) systems are usually widely distributed and have hierarchical operational organizations. They are continuously changing in accordance with various requirements and environments. Therefore, they need to be flexible enough to quickly adapt to those changes. SCOPE classifies software for conventional electric power systems into three hierarchical layers, the Application dependent part, the Power system dependent part and the Computer system dependent part. The power system dependent part realizes flexibility for changing of power system equipment and operational organization by introducing a reduction relationship which enhances the generalize/specialize relationship of object oriented technology. SCOPE architecture enables EMS/SCADA systems to be flexible, and also enables efficient and economic development. It is confirmed through developing and evaluating a SCOPE prototype system that the flexibility of EMS/SCADA systems is improved.

A fault-tolerant architecture based on autonomous replicated objects

The paper proposes an architecture for the replication of program modules enabling them to behave in accordance with their own local knowledge, without any influence by not only their location, replication degree and fault-tolerant mechanism but also system level modules. In the proposed architecture, program modules are implemented as objects and communication among them is carried out by a total ordering broadcast protocol, enabling individual objects to behave autonomously. Therefore, individual objects can choose the most suitable replication degree and fault-tolerant mechanism in accordance with their own required reliability and execution efficiency without the need to change programs or for the object location to be influenced.<<ETX>>

A Fault-Tolerant Architecture for the Intellectual Distributed Processing System

The Intellectual Distributed Processing System (IDPS) is a system architecture to realize highly extensible and adaptive distributed systems. The reliability of the IDPS relies on replicated objects model, and this paper presents two new mechanisms for implementing that model on the IDPS. One is a fail-stop broadcast communication protocol, where replicated objects receive the same messages in the same order. The other is a commitment method, where each object receives only correct messages. By these mechanisms, an individual object does not need to be aware of the replication degree and the location of relevant objects. Moreover, each object can communicate with other individual objects without confirming message transmission. Therefore, the overhead for the fault-tolerant mechanisms can be maintained at a small level.

Intellectual Distributed Processing System Development

The Intellectual Distributed Processing System (IDPS) is a system which has no centralized managing element. IDPS system elements find their roles autonomously in order to complete objectives given to the system. IDPS system elements are also able to solve conflicts among different objectives without any supervisory element, by exchanging information among elements.

Distributed Deadlock Avoidance and Detection in Intellectual Distributed Processing System

Distributed systems have advantages in developing large, flexible, and reliable systems. The Intellectual Distributed Processing System(IDPS) eliminates all central managing mechanisms from systems in order to make the best use of these advantages. This paper describes the deadlock avoidance and detection method adopted in the IDPS. The proposed mechanism has the following characteristics. 1) The proposed mechanism, which is completely distributed, is carried out by communication among jobs and resources. Therefore, it is possible to make highly flexible and reliable systems easily, Moreover, the proposed mechanism does not trace individual hold-claim and/or hold-wait relations in directed graphs sequentially. Therefore, it is possible to execute deadlock handlings in parallel on different sites. 2) It is possible to use deadlock avoidance and detection mechanisms simultaneously. Deadlock detection is used for data resources and deadlock avoidance is used for physical resources.