Byzantine Fault-Tolerant Web Services for n-Tier and Service Oriented Architectures

Mission-critical services must be replicated to guarantee correctness and high availability in spite of arbitrary (Byzantine) faults. Traditional Byzantine fault tolerance protocols suffer from several major limitations. Some protocols do not support interoperability between replicated services. Other protocols provide poor fault isolation between services leading to cascading failures across organizational and application boundaries. Moreover, traditional protocols are unsuitable for applications with tiered architectures, long-running threads of computation, or asynchronous interaction between services.