Optimizing Paxos with request exchangeability for highly available web services

There are a variety of factors such as massive commodity computers, storage, network devices and complex management tasks running behind web services which make web services not available. Replication is an effective solution in that case. There are a variety of replication protocols, and which has been used most is called Paxos. For high available web services, we introduce Paxos as replication protocol and have done a series of optimization work. Firstly, we find that there exists exchangeability between requests to web services and the exchangeability can be used to improve the performance of Paxos. Secondly, in the light of the characteristics of web services with business processes, we find the exchangeable relationship between operations. The exchangeability between operations and the exchangeability between requests can be one-to-one correspondence. Thirdly, we apply the exchangeability to the optimization of Paxos for high available web services. Finally, we have implemented some experiments and experimental results show its effectiveness and performance advantages compared with other replication methods.