What is OASIS?OASIS (Overlay Anycast Service InfraStructure) is a shared locality-aware server selection infrastructure. OASIS is organized as an infrastructure overlay, providing high availability and scalability. At a high level, OASIS allows a service to register a list of servers, then answers the query, ``Which server should the client contact?'' Selection is primarily optimized for network locality, but also incorporates liveness and load. OASIS can, for instance, be used by CGI scripts to redirect clients to an appropriate web mirror. It can locate servers for IP anycast proxies, or it can select distributed SMTP servers in large email services. OASIS is publicly deployed on PlanetLab and has already been adopted by a number of services. Currently, we have implemented a DNS redirector that performs server selection upon hostname lookups, thus supporting a wide range of unmodified client applications. We also provide an HTTP and RPC interface to expose its anycast and locality-estimation functions to OASIS-aware hosts. Please note that the live version of CoralCDN has yet to be switched over to OASIS during our alpha testing phase. Check out a real-time map of our current deployment:
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