Dependability Assessment of an OGSA Compliant Middleware Implementation by Fault Injection

This paper presents our research on applying our dependability assessment method to an OGSA compliant middleware product. Our initial proof of concept experiment was implemented using a stateless Tomcat web server and Apache SOAP. This research adapts and enhances our existing fault injection software (OGSA-FIT) from the stateless environment of a standard web service to the stateful environment of an OGSA Toolkit (Globus). We compare our initial proof of concept experiment to our new target system based on the Globus Toolkit. The Globus Toolkit is implemented around an Apache Tomcat server using the Axis SOAP library as well as OGSA interfaces and libraries. We address issues arising from latencies introduced into the system by OGSA-FIT. We introduce a model for calculating this latency and introduce new mechanisms into the software to reduce this. We also present results from our initial experiments, which showed a problem with an alpha version of the Globus Toolkit. We detail future research including plans to enhance our user GUI to provide semi-automatic test campaign generation. Also since our OGSA-FIT software is intended to support both OGSA based middleware as well as standard SOAP based web-service environments we outline our research into providing interchangeable personality modules.