Web信息抽取系统的设计与实现

1、ELF: An Efficient Log-Structured Flash File System For Micro Sensor NodesBy Hui Dai, Michael Neufeld, Richard HanTalk given by Mingqu YueOutlineBackgroundsDesign OverviewImplementationData structuresFile operationsGarbage collectionCrash recoveryPerformance EvaluationBackgroundsMicro Sensor NodesCol

2、lecting data and cooperatively relay the data back to a more powerful collection point.Need to store data locallyFlash memorytwo orders of magnitude more memory than RAMenables the design of reliability mechanisms to recover sensor data after crashes. FeaturesConstrained resourceFlash access times a

3、re fixedWear levellingDesign OverviewObjectiveCharacteristics of data that are expected to handlePersistent storage attributes on sensor nodesLog-Structured File System Techniques in ELFELF Architecture OverviewImplementationOn-Flash Data StructuresIn-Memory Data StructuresIn-EEPROM Data Structures

4、and Related OperationsFile Operations in ELFResource Management and Garbage CollectionCrash RecoveryPerformance Evaluation (compared with Matchbox)Sequential Read PerformanceSequential Write PerformanceRandom Read PerformanceRandom Write PerformanceWear Levelling PerformanceEnergy ConsumptionFuture workIssues like frequent occurrence of rebooting , file opening and creationCaching writes enhance the risk of data lossA more detailed study of the reliability neededI