ITR: System Support for Automatic and Consistent Replication of Internet Services

这个项目探索了两种互补的技术，以解决复制网络服务的基本限制。该建议的第一个方面寻求自动复制服务程序和状态信息，以允许动态服务的透明缓存或复制。这项研究的目标是允许动态服务的透明缓存或复制，这是将不可伸缩的服务实现自动转换为可伸缩服务实现的关键一步。这项工作的第二个主旨是允许网络服务动态地交换副本一致性，以提高系统可用性和性能。TACT(可调可用性和一致性权衡)工具包允许互联网服务灵活且动态地选择它们自己的可用性/一致性权衡。我们使用三个一致性度量：数值误差、顺序误差和陈旧程度来捕捉互联网服务特定应用的一致性需求。除了应用程序特定的参数之外，应用程序还使用这些度量来为系统一致性分配一个数值，例如，由于底层复制一致性而最终必须回滚的用户请求的百分比。最后，TACT允许在用户、客户端和副本的基础上指定一致性，从而实现差异化的服务质量。

This project explores two complementary techniques for addressingfundamental limitations in replicating network services. The first aspectof this proposal seeks to automatically replicate service programs andstate information to allow transparent caching or replication of dynamicservices. The goal of the research is to allow transparent caching orreplication of dynamic services, a key step toward automatically convertingunscalable service implementations into scalable ones. The second thrust ofthis work is to allow network services to dynamically trade replicaconsistency for increased system availability and performance. The TACT(Tunable Availability and Consistency Tradeoffs) toolkit allows Internetservices to flexibly and dynamically choose their ownavailability/consistency tradeoffs. We use three consistency metrics,Numerical Error, Order Error and Staleness to capture application-specificconsistency requirements of Internet services. Applications use thesemetrics in addition to application-specific parameters to assign a numericvalue to system consistency, e.g., the percentage of user requests thatmust eventually be rolled back because of underlying replicainconsistency. Finally, TACT allows consistency to be specified on aper-user, client, and replica basis, enabling differentiated quality ofservice.