Replication issues in the MAP/MMS communication environment

Abstract

Distributed systems consist of a set of computers (usually called nodes) that communicate through a network. The communication is achieved through the exchange of messages with the help of a communication protocol. In order to enhance the tolerance of such systems in the presence of faults, replication of information on different nodes is a commonly used strategy.Open distributed systems provide homogeneous way to connect heterogeneous components because they use standard protocols. In industrial environment, the MAP/MMS protocol (which is based on the ISO/OSI standard) is widely used. However, this protocol does not support replication management. In order to overcome this deficiency, this paper will address the issue of maintaining coherency among multiple copies of information. More precisely, issues related to the adaptation and implementation of an algorithm used in distributed systems [8] to the MAP/MMS communication environment will be examined in detail.MAP/MMS is based on the client/server communication model. The algorithm is first modified such that it can be used in conjunction with this model. Performance study is conducted for the implementation with MMS with respect to the number of messages exchanged for each service request and to the number of MMS Object definitions.