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The Globus eXtensible Input/Output System (XIO): A protocol independent IO system for the Grid

The Globus eXtensible Input/Output System (XIO): A protocol independent IO system for the Grid. Bill Allcock, John Bresnahan, Raj Kettimuthu and Joe Link Argonne National Laboratory. Grid IO. Geographically disperse resources Supercomputers/clusters Large data store

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The Globus eXtensible Input/Output System (XIO): A protocol independent IO system for the Grid

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  1. The Globus eXtensible Input/Output System (XIO):A protocol independent IO system for the Grid Bill Allcock, John Bresnahan, Raj Kettimuthu and Joe Link Argonne National Laboratory

  2. Grid IO • Geographically disperse resources • Supercomputers/clusters • Large data store • Specialized scientific devices • Telescopes, environmental sensors • Collaborative sessions • Access Grid • Varying network and file transfer protocols • TCP, UDP, XCP, GridFTP etc

  3. Typical Approach

  4. Example Application

  5. Problems • Development time • Application must learn to use many different APIs • Each API has its own semantics • Asynchronous/Synchronous • Threaded/non-threaded • Scalability and compatibility • Application must be modified to work with new protocols/devices • Application must keep up with orthogonal research issues

  6. Observations • Data stream IO abstraction • Many Grid IO needs can be treated as a stream of bytes • Open/close/read/write functionality satisfies most requirements • Protocol details • Rarely does the application need to deal with protocol details • Most needs can be satisfied at initialization time

  7. Solution • Globus XIO user API • Single API/single set of semantics • Simple open/close/read/write API • Driver abstraction • Hides protocol details • Allows for extensibility • Drivers can be selected at runtime

  8. Globus XIO Approach

  9. Example Application with XIO

  10. Drivers • Make single API do many types of IO • Specific drivers for specific protocols/devices • Transport • Moves data out of process space • TCP, UDP, File etc • Transform • Manipulate or examine data • Do not move data outside of process space • Compression, security etc

  11. Stack • Transport • Exactly one per stack • Must be on the bottom • Transform • Zero or many per stack • Control flows from user to the top of the stack, to the transport driver

  12. Driver development • A set of function signatures • Implemented by the driver • Registered with Globus XIO • Semantics • XIO makes calls to these functions expecting specific behavior • Read() interface function should produce data and write() should consume data

  13. Attributes and controls • Way to expose functionalities specific to a protocol • User API to control the attributes and special features of a driver • An opportunity to tweak parameters specific to a driver • Attributes and controls support is optional and a driver may choose not to have it

  14. Globus XIO Framework • Moves data from user to driver stack • Manages the interactions between drivers • Assist in the creation of drivers • Asynchronous support • Close and EOF barriers • Error checking • Internal API for passing operations down the stack

  15. Existing drivers • Transport • TCP, UDP, File, GridFTP • UDT - UDP based reliable data transport protocol • Multi-stream - uses multiple transport protocol streams for data transfer • Transform • GSI, HTTP, Ordering

  16. Performance analysis • Compare with raw sockets and Globus IO • Latency tests • Ping-Pong tests, 1000 times, average of 10 runs • Loopback, LAN and WAN • Bandwidth tests • Send 1000 back-to-back messages and wait for reply, average of 10 runs • LAN and WAN

  17. Latency over Loopback Interface

  18. Latency comparison on LAN

  19. Latency comparison on a WAN

  20. Bandwidth on a LAN

  21. Bandwidth on a WAN

  22. Multiple drivers on a stack

  23. Summary • Provides a simple and uniform IO API • Appropriate for most byte stream oriented applications • Ability to quickly adapt to • Different transport protocols • Different data access mechanisms • Provides a convenient framework for research and development

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