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Standards-based Access to LFCs: Interoperability and Grid Standards

This study focuses on creating a standards-based interface for accessing data resources in EGEE Grids, specifically aiming to read data from LCG File Catalogs via a standardized interface to enable interoperability. The paper covers the development, interoperability, and performance aspects, emphasizing the importance of grid standards. Key areas such as Infrastructure, Security, APIs, and Data handling are discussed in detail, along with the implementation of RNS and ByteIO operations using gLiteAPIs. The use of Apache Axis2/C in developing web services is also highlighted. The study concludes by discussing the successful implementation of RNS and ByteIO specifications for existing grid systems and suggesting future directions for enhancement.

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Standards-based Access to LFCs: Interoperability and Grid Standards

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  1. Standards-based Access to LFCs Karolina Sarnowska, University of Virginia Andrew Grimshaw, University of Virginia Mark Morgan, University of Virginia AkosFrohner, CERN Erwin Laure, KTH

  2. Outline • Introduction • Development • Interoperability • Performance • Conclusion

  3. Interoperability and Grid Standards Introduction

  4. Goal & Motivation • Create a standards-based interface for accessing data resources in EGEE grids • Read data from LFCs via standardized interface • Enable interoperability • Validate specifications

  5. LFC: The LCG File Catalog • Catalog of data files on storage elements • Each logical file entry can correspond to multiple physical files (replicas) • Provides mapping between logical file names and storage URLs LFC /grid /atlas /alice /cms Storage Elements EGEE Grid SE SE

  6. OGF Standards • Infrastructure WS-Addressing, Resource Namespace Service (RNS), WS-Naming • Compute JSDL, OGSA-BES, HPC Basic Profile • Data RNS, OGSA-ByteIO, gridFTP, WS-DAI • APIs SAGA, DRMAA, GridRPC • Security WSI-BSP, WS-Security, WS-Trust, WS-Federation, WSSecurityPolicy, WS-SecureNaming, WS-Secure Communication

  7. Step One: Identify Resource • Need means of referring to resources • What’s in a name? • human-readable • maps to unique resource

  8. The RNS Specification • RNS: Resource Namespace Service • Describes standard way of mapping names to grid endpoints • RNS 1.0 Operations: Add, List, Remove, Query, Move

  9. The SNARL Service:An Implementation of RNS Standards-based Naming for Accessing Resources in an LFC LFC /grid /atlas /alice /cms /dteam EGEE Grid Another Grid (1) RNS Requests SE Grid Client SE SNARL Service Storage Elements (2) LFC API Calls (3) RNS Responses

  10. Step Two: Access Resource Data • Need means of accessing data associated with resources

  11. The ByteIO Specification • Describes standard way of handling transfer of data associated with grid entities • POSIX-like interface • Random, session-less or stateful session access • Operations: Read, Write, Append, TruncAppend, SeekRead, SeekWrite

  12. The SABLE Service:An Implementation of ByteIO Standards-based Access to Bytes of LFC Entries EGEE Grid LFC /grid /atlas /alice /cms /dteam Another Grid (1) ByteIO Requests SABLE Service SE Client Storage Elements SE (2) GFAL API Calls (3) LCG & GFAL API Calls (3) ByteIO Responses

  13. Creating web services with Axis2/C Development

  14. Development Process • Setup web services framework with Axis2/C • Create skeleton services with WSDL2C • Create clients for testing • Implement RNS and ByteIO Operations using gLiteAPIs

  15. Why Apache Axis2/C? • Web services engine implemented in C • Handles SOAP message processing • Built-in support includes: • WS-Addressing • WS-Policy • WS-SecurityPolicy

  16. Service Skeleton Generation with WSDL2C Tool • Specify web service in WSDL file • Use tool to generate C web service skeleton Resulting Service Skeleton Size: SNARL: 89k LOC SABLE : 77k LOC

  17. Test Client Creation • Example: RNS Add Request <soap:Envelope> <soap:Header> <wsa:Action>http://schemas.ggf.org/rns/2006/03/rns/add</wsa:Action> </soap:Header> <soap:Body> <rns:addxmlns:rns=‘http://schemas.ggf.org/rns/2006/05/rns’> <rns:entry_name> foo </rns:entry_name> </rns:add> </soap:Body> </soap:Envelope>

  18. Implementing RNS Ops • Translating RNS operations to API calls • Should replicas be visible to users?

  19. Revealing Logical Files vs. Replicas (1) RNS List Grid Client SNARL Service (3) RNS List Response (2) LFC API Calls • SE • fooReplicaA • LFC • /grid/foo • SE • fooReplicaB

  20. Implementing ByteIO Ops • Translating ByteIO operations to API calls • Should writes be allowed?

  21. Interoperability Tests

  22. Spec Adoption

  23. Interoperability Test Setup • Using RNS list request, choose LFC entry • Using ByteIO read request, read data resource associated with LFC entry

  24. Step One:List LFC Entries via SNARL EGEE Grid LFC /grid /atlas /alice /cms /dteam GenesisII Grid Grid Client (1) RNS List Request (2) LFC API Calls SE SE (3) RNS List Response Storage Elements SNARL Service

  25. Step Two: Read Resource Data via SABLE GenesisII Grid EGEE Grid LFC /grid /atlas /alice /cms /dteam ByteIO ReadRequest Grid Client SABLE Service SE (3) ByteIO Read Response SE Storage Elements (2) GFAL API Calls

  26. performance

  27. Setup: Machine Specs • Scientific CERN Linux 4 • Intel Pentium 4 2.8 GHz CPU • 1 GB memory

  28. SNARL Performance

  29. SABLE Performance

  30. Conclusions

  31. Future Directions • Add security context • Implement MIME, DIME, MTOM • Explore use as interface between LFC and other tools • Update for RNS 1.1 • Implement StreamableByteIO

  32. Conclusion • Implementation of RNS and ByteIO specification for existing grid system is possible • RNS and ByteIO provide an interface that enables the sharing of grid data

  33. Thank You! • CERN & DM Team • UVA Genesis II Team • OpenLab Program at CERN

  34. "Open Grid Forum," http://www.ogf.org. M. Pereira, O. Tatebe, L. Luan, and T. Anderson, "Resource Namespace Service Specification,” http://www.ggf.org/documents/GFD.101.pdf, 2006. M. Morgan, “ByteIO Specification,” http://www.ggf.org/documents/GFD.87.pdf, 2006. M. M. Morgan and A. S. Grimshaw, "Genesis II – Standards Based Grid Computing," Seventh IEEE International Symposium on Cluster Computing and the Grid, 2007. “Apache Axis2/C,” http://ws.apache.org/axis2c Questions?

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