A redundant nested invocation suppression mechanism for active replication fault-tolerant web service

Zwass suggested that middleware and message service is one of the five fundamental technologies used to realize Electronic Commerce (EC). The Simple Object Access Protocol (SOAP) is recognized as a more promising middleware for EC applications among other leading candidates such as CORBA. We notice that the fault-tolerance issue is somewhat neglected in the current standard, i.e., SOAP 1.1. We therefore proposed a fault tolerant web service called fault-tolerant SOAP or FT-SOAP through which web services can be built with higher resilience to failure. Active replication is a common approach to building highly available and reliable distributed software applications. The redundant nested invocation (RNI) problem arises when servers in a replicated group issues nested invocations to other server groups in response to a client invocation. In this work, we propose a mechanism to perform auto-suppression of redundant nested invocation in an active replication FT-SOAP system. Our approach ensures the portability requirement of a middleware, especially for FT-SOAP.