The Reliable Server Pooling Framework RSerPool Features: Lightweight Realtime Scalable Extendable Simple RSerPool Terminology: Pool Element (PE): Server Pool: Set of PEs PE ID: Unique ID of PE Pool Handle: Unique ID of pool Handlespace: Set of pools Registrar (PR) Pool User (PU): Client RSerPool Protocols: ASAP (Aggregate Server Access Protocol) ENRP (Endpoint HaNdlespace Redundancy Protocol) Our Demo System Usage of SCTP for: Multi-Homing Network Path Redundancy Dynamic Address Reconfiguration Message Framing Thomas Dreibholz's Reliable Server Pooling Page http://tdrwww.exp-math.uni-essen.de/dreibholz/rserpool/ Application Example Policy-Based Server Selection Session Establishment (PU requests service from a pool): PU asks any PR (e.g. local PR in its LAN) to resolve pool handle to list of PEs PR selects set of PEs by pool's selection policy (e.g. round robin) PU puts PE set into its local cache PU selects one PE, again by policy, and establishes application connection Subsequent requests may be satisfied from cache (default timeout: 30s) Failover (PU handles a PE failure): PU should report the PE's failure to its PR (PR may decide to remove this PE from the handlespace) PU selects a new PE (from its cache , or by PR query ) PU invokes an application-specific failover procedure (Example: file download - tell new PE the file name and last position) Selections 1 2 SS7 Gateway for Telephone Signalling over IP Networks Client-Based Application State Sharing Our Research Activity Fast Server Selection Policy Performance: Which server should be selected? Different capacities Current load status => Definition of appropriate pool policies Our Prototype Implementation Our New Policies Existing Policies Our New Policies Weighted Random Static Non-Deterministic Priority Least Used Dynamic PE provides information ''How much does a new job increase my load?'' Use PE that will be least loaded after it gets a new job Design Decisions Open Source (GPL License) Platform independence Currently: Linux, FreeBSD, Darwin, Solaris Implemented in ANSI-C Basic Components rsplib Library ASAP protocol Basic Mode API for PE/PU <-> PR communication Enhanced Mode API: The RSerPool Session Layer Registrar ENRP protocol New policies achieve significant performance gain Contribution to the standard -> Internet Draft (Status: IETF RSerPool Working Group Document) http://tdrwww.exp-math.uni-essen.de/dreibholz/rserpool/