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) [24]. 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 [23]. 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 [14]. 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-SOAR.