• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.23-31
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• 2001

Current CORBA has been suggested a solution for complexity of software in distributed environment. But it can't provide reliability about data transfer. For instance, CORBA can't provide object to client when the network are unstable or congested. In an existing CORBA, client has to wait when there is congestion between client and object implementation while client get a service from object implementation. So In this paper, we propose Fault-Tolerant CORBA Service (FTS) which has an intelligent redirection about an object that client requests. Moreover, we designed and implemented Fault-Tolerant Service to provide reliability by extending existing CORBA ORB. Therefore it provides reliable connection throughout the proposed Fault-Tolerant Service.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1199-1202
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• 2000

CORBA 환경에서 지속적이고 안정적인 객체 서비스틀 제공하기 위해 기존 CORBA에 고장 감내 기능을 부여한 Fault-Tolerant CORBA가 필요하게 되었다. Orbix+ISIS, Eletra 등이 CORBA에서 고장 감내 기능을 제공하고 있으며 OMG에서도 Fault-Tolerant CORBA 규격에 관한 작업을 진행 중이다. CORBA 환경에서 고장 감내 기능을 ORB 에 추가하는 방법은 통합 방식(Integration Approach), 서비스 방식(Service Approach), 인터셉트 방식(Intercept Approach) 등이 있다. 본 논문에서는 OMG에서 작업 중인 Fault-Tolerant CORBA 규격을 기본으로 하여 통합 방식과 서비스 방식을 결합하여 클라이언트 응용에게 투명하게 고장 감내 기능을 제공하는 Fault-Tolerant CORBA 구조를 설계하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.267-269
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• 1999

고장 감내형 CORBA*Fault Tolerant Common Object Broker Architecture)는 분산 객체 시스템 통합기술의 표준인 CORBA에 고장에 대한 회복수단을 제공하기 위해 제안되었다. CORBA에 고장 감내성을 추가하기 위해서는 객체단위의 중복그룹의 관리, 호출 구조 및 이에 따른 고장인지 및 회복기법이 필요하다. 기존에 제안된 분산 시스템 환경에서의 고장인지 및 회복기법들은 프로세스 단위의 동작, 실행시간에 생성된 객체의 동적 환경구성 기능의 부제 등의 문제로 고장 감내형 CORBA에 적용시키기에는 많은 문제점을 가지고 있다. 따라서, 본 논문에서는 사용자에게 고장투명성과 연속적인 서비스 제공을 보장하는 고장 가내형 CORBA에 필요한 핵심기술인 객체 그룹간 고장인지 방법 및 고장으로부터의 회복 메커니즘을 제안한다.

• The KIPS Transactions:PartD
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• v.10D no.6
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• pp.991-998
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• 2003

There are many methods to enhance the fault tolerance of the CORBA based real time systems by viewpoints. Among them, this paper provides a method to enable seamless services where the systems based on the CORBA have object's faults originated processing real time information. Namely, this paper observes a method to deal efficiently with object's faults happening in 3 tier architecture environments. It is possible to replicate objects as a way to enhance the fault tolerance considering object's faults. Along with it, this paper shows a method to enhance the fault tolerance ultimately and then keep the service continuity by prividing a way to allow to continue to run the systems until the FT-CORBA based one's faults are recovered.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.562-572
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• 2002

Distributed object technologies have become popular in developing distributed systems. Although such middleware platforms as DSOM, DCOM, CORBA and Java RMI ease the development of distributed applications, they do not directly improve the reliability and the availability of these applications. Because the task of developing fault-tolerance techniques for distributed object paradigms is often complicated and error-prone, there is a great need for a development toolkit that enhances the reliability and the availability of distributed objects. In this paper, we propose a fault-tolerant distributed middleware system based on RMI, called IMMORTAL. We use a log-based rollback-recovery mechanism for supporting reliable distributed computing. Through a series of experiments, we observe that benchmark applications on the IMMORTAL tolerate hardware and software failures and evaluate its performance and scalability.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.209-211
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• 1999

본 논문에서는 CORBA의 고장 감내(fault tolerance) 방식을 이용하여 교환기 시스템을 위한 객체 지향 실시간 운영체계상에서의 고장 감내 객체서비스 구현을 목표로 한다. 이를 위해 먼저 CORBA의 고장 감내 방식을 분석하고, 전자 교환기에 적합한 실시간 고장 감내 방식에 대하여 제안한다. 이 방식에서는 교환기내의 이중화 시스템을 이용하여 객체 단위에서 고장 감내 기능을 제공하게 된다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.157-159
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• 2000

분산 객체 시스템을 통합하기 위한 표준인 CORBA(Common Object Request Broker Atchitecture)는 분산 환경에서 더욱 더 자주 발생하는 고장에 대한 회복 수단을 제공하지 않기 때문에, 높은 신뢰성을 요구하는 상업용 어플리케이션에 도입되지 못하고 있다. 이에 따라, CORBA 구조 내에 자체적인 고장 감내 구조를 추가해 신뢰성 높은 서비스를 제공할 수 있는 고장 감내 CORBA에 대한 연구가 진행되고 있다. 그러나, 2000년 4월에 채택된 고장 감내 CORBA에 대한 명세서에서는 객체의 인터페이스를 정의하는 기술 언어인 CORBA IDL(Interface Definition Language)로 객체 단위의 중복과 이를 위한 시스템의 구조 및 각 모듈의 설계를 요약하고 있으나, 그 세부적인 메커니즘이 제시되지 않고 있다. 따라서 본 논문에서는 CORBA에 고장 감내성을 부여하기 위해 세부적인 고장 감내 CORBA를 위한 로깅 및 회복 기법을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.2
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• pp.1-9
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• 2002

The use of Object-Oriented Distributed Programming(OODP) environment such as DCOM, DSOM, Java RMI, CORBA to implement distributed applications is becoming increasingly popular. However, absence of a fault-tolerance feature in these middleware platforms complicates the design and implementation of reliable distributed object-based applications, although they greatly enhance the quality and reusability of the distributed object-based applications. In this paper, we propose a fault-tolerant programming environment based on RMI, namely Evergreen, for the reliable distributed computing with checkpoints and rollback-recovery mechanism. Based on a series of experiments, we evaluate the performance of Evergreen and find its possibility of extension to fully support our optimal design goal.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.461-468
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• 2001

Large-scale distributed applications based on Internet and client/server applications have to deal with series of problems such as load balancing, unpredictable communication delays, partial errors, and networking failures. Therefore, sophisticated applications such as teleconferencing, video-on-demand, and concurrent software engineering require an abstracted communication. In this paper, we present our design, implementation and performance analysis of group communication using the CORBA ORB, JAVA RMI, Socket based on distributed computing. We anticipate our study may apply to the various field of applications such as fault-tolerant client/server system, groupware, scalable text retrieval system, and financial information systems.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.2
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• pp.121-131
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• 2001

The failure of network and/or node on which server object is executed is a single point of system failure in the CORBA application. One of the possible ways to overcome such problem is to replicate server objects to several independent nodes. The replicated objects executing same tasks are called object group. In order to provide fault tolerance of server object, this paper proposes and implements new CORBA model that supports the object group based on active replication. The proposed model not only provides interoperability with existing CORBA application but also minimizes additional application interface required to support object group because it uses nop to exchange messages between client and server. And this paper extends IDL structure. Depending to application logic, it makes possible to prevent performance degradation caused by consistency maintenance. At present, this paper supports only active replication. But it can be easily extended to provide warm ancVor cold passive replication without modification of architecture required for active replication.