VOEventNet Overview & Status

John Swinbank

Transcript

1. John Swinbank, swinbank@transientskp.org
   Vice Chair, IVOA Time Domain Interest Group
   LOFAR TKP Project Meeting
   3 December 2012, Amsterdam
   VOEventNet
   Overview & Status
   

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2. Transient Notifications
   

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3. Transient deluge
   • LSST promises us 2×106 transients/night
   (Two! Million!)
   • How will you decide what’s interesting
   for your science case? That’s a lot of
   ATels to read...
   • The faster your follow-up, the
   (potentially) better your science
   

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4. Standard tools
   • A solved problem (sorta)
   • XML
   • eXtensible Markup Language
   • “defines a set of rules for
   encoding documents in a format that is both
   human-readable and machine-readable”
   • Widespread acceptance means many off-the-
   shelf tools, libraries and procedures.
   

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5. VOEvent
   Who?
   What?
   When?
   How?
   So what?
   

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6. Transport
   • VOEvent is transport agnostic
   • Write it down, send an e-mail, engrave on
   stone tablets, ...
   • VOEvent Transport Protocol
   Alasdair Allan, Robert B. Denny, John Swinbank
   IVOA Note, Version 1.2 coming soon
   Draft version on request
   

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7. VTP Overview
   Broker
   Author
   Subscriber
   VOEvent
   Acknowledge
   Subscriber
   Subscriber
   Keep
   A
   live
   Keep
   A
   live
   VO
   Event
   VO
   Event
   Keep
   A
   live
   Keep
   A
   live
   

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8. VOEvent Backbone
   Broker
   Broker
   Broker
   Broker
   Watch out
   for loops!
   

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9. Comet
   http://comet.transientskp.org/
   

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10. Value Added Services
    • A broker may provide
    additional services to its
    subscribers
    • Filter event streams
    • Any node may provide
    additional services based
    on events received
    • Store in a database
    • Display on a web page
    • Perform a follow-up
    observation(!)
    http://www.skyalert.org/
    

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11. Stream Filtering by Comet
    • “XPath, the XML Path Language, is a query language for
    selecting nodes from an XML document. In addition, XPath
    may be used to compute values (e.g., strings, numbers, or
    Boolean values) from the content of an XML
    document” (Wikipedia)
    • Comet lets subscribers specify an XPath expression and only
    forward events for which it evaluates to true (or non-zero)
    • /*[local-name()="VOEvent" and @role!="test"]
    • //Who[AuthorIVORN="ivo://lofar.transients/"]
    • This is a Comet “special”, not an IVOA standard.
    

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12. Breaking news!
    FAKE
    

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13. A Short PGP Primer
    Alice Bob
    Alice wants to communicate securely with Bob
    ?
    And sends half to Bob
    Alice can sign with her key.
    Bob can verify the signature.
    A signature guarantees the sender of the
    message had possession of Alice’s key.
    She generates a PGP “key”
    PGP is an internet standard (RFC 4880) with
    various free & commercial implementations.
    

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14. Bits, bytes & infosets
    • A PGP signature guarantees the bits
    which make up the message are
    unchanged
    valuevalue2
    value
    value2
    • What is the legitimate role of a broker
    or repository?
    

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15. Standards & Support
    • Digital Signatures in VOEvent Messages,
    Robert B. Denny & John Swinbank,
    IVOA Note, Version 2.0
    coming soon (draft version by request).
    • Supported by the development version of
    Comet.
    • ...will this address all your use cases?
    

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16. Also on the horizon...
    • VOEventRegExt
    • How do you find a VOEvent broker?
    • How do you get hold of an event
    given an IVORN?
    • Time series data model
    • ... others
    • Please get involved!
    http://www.voevent.org/
    

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