Rep4WS: A Paxos Based Replication Framework for Building Consistent and Reliable Web Services

Web services are widely used to enable remote access to heterogeneous resources through standard interfaces and build complex applications by reusing existing component services. However, massive commodity computers, storage, network devices and complex management tasks running behind web services make them subject to outage and unable to provide continuously reliable services. To address this issue, we present a Paxos-based replication framework for building consistent and reliable web services. The framework mainly consists of a replication protocol and a set of failure tackling algorithms. First, in the replication protocol, besides keeping consistency of service replicas we introduce pipeline concurrency and RDG (Request Dependency Graph) to traditional Paxos so as to improve its performance. Second, we design failure recovery algorithms to recover the failed nodes, which guarantee that each web service has enough available replicas and thus can deliver expected reliability. Third, through an extensive set of experiments, we show that our method is effective in terms of keeping consistency and reliability of web services and it outperforms other replication methods.