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Objective. What is RFT ? How does it work Architecture of RFT RFT and OGSA Issues Demo Questions. What is Reliability. The ability of a system or component to perform its required functions under stated conditions for a specified period of time. (IEEE)

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objective
Objective
  • What is RFT ?
  • How does it work
  • Architecture of RFT
  • RFT and OGSA
  • Issues
  • Demo
  • Questions
what is reliability
What is Reliability
  • The ability of a system or component to perform its required functions under stated conditions for a specified period of time. (IEEE)
  • What is Reliability in the context of File Transfer (What is the scope of the problem )
  • How much of it we want to address ?
  • Reliability can mean different things to different people
  • Hash out something that is most general and acceptable to wide range of applications.
our goal
Our Goal
  • To design and implement a Service that allows byte streams to be transferred in a Reliable manner
  • Reliability,in our context, means that problems of less than a certain,user defined magnitude are dealt with automatically.
  • Build prototypes using different technologies.
    • Java
    • Web Services
    • Etc..
our goal cont
Our Goal (cont..)
  • A non user based service
    • GridFTP already provides restart markers for recovery but however the client needs to be active.
    • Loss of client requires a manual restart from scratch
  • Store transfer state persistently
  • Recover from a set of Failure conditions reliably
failure conditions
Failure Conditions
  • List of Failure conditions we want to address
    • Network Failures like dropped connections
    • Machine crashes
    • Temporary Network outages
    • Failure of File Systems
    • Etc…
interface
Interface
  • submitTransfer()
    • Set of URLs
    • File size for partial file transfers
  • getStatus()
  • cancelTransfer()
  • resumeTransfer()
ogsa and rft
OGSA and RFT
  • How does RFT fit in OGSA?
  • Things that are different from SC Demo
  • RFT is a Web Service
  • Single Transfer Reliability
  • Service Definition in WSDL
  • Talks XML over SOAP just like any standard Web Service
rft web service interface
RFT Web Service Interface
  • submitTransferJob()
    • Intput message:fromURL and toURL (strings)
    • Output message: transferJobID (integer)
  • commitTransferJob()
    • Input message: transferJobID
    • Output message: transferJobID
  • getStatus()
    • Input message: transferJobID
    • Output message: status (integer)
  • getStatistics()
    • Input message: transferJobId
    • Output message: Statistics ( complex type)
our experience
Our Experience
  • SC2001 Demo
  • List of Tests
    • Longest – 3 days transferring 0.3 Terabytes of data from ANL to NERSC
  • Failures recovered from
    • NFS Failures
    • Network outages
    • Server crashes
issues
Issues
  • Language
    • Prototypes are in Java
    • Language issue should not matter since it is a service whose interface is a socket
  • Persistence Mechanism
    • We used PostGreSQL as database to store the transfer state
    • Can we use File based persistence mechanism
  • Scalability
    • Multiple instances of RFT which may appear as a single logical entity
    • Request redirection ?
issues cont
Issues (cont..)
  • XRM Functionality
    • Reservations for disk and bandwidth
  • Higher Level Services
    • Interaction between RFT and Higher level Services like Reliable Replication Service
    • Scheduler ??
    • Services like NWS that can give performance estimates
  • ComputeJob Submission
    • File transfer as a Job ?
issues cont1
Issues(cont..)
  • Security
    • CAS
    • Proxy renewal
  • Error Propagation
slide15
DEMO
  • SC2001 Demo
  • OGSA and RFT
more info
More Info
  • http://www.mcs.anl.gov/~madduri/RFT.html
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