[saga-rg] Advert Service Interface

[Andre Merzky]

Hi all, 

attached is yet-another-proposal for a future SAGA
extension.  Please note that this proposal is not intended
to enter the SAGA API draft anytime soon - however, it would
be nice to get feedback on this early on.

Motivation:

  Interfaces to information Services are _neccessary_ on
  Grid Middleware Level, in order to allow informed
  decisions of resource avialability, to store persitant
  information about system configurations etc.  Well, you
  know.

  On application level, a number of uses cases require (or
  at least can benefit) from a interface to persistent
  global information storage as well.  A simple example is a
  streaming server and client, where the handshaking
  procedure is greatly simplified by read/write access to
  such an information repository - all other solutions need
  global knowledge.

  In GridLab (and the GAT), we have very good experiences
  with what we called the AdvertService.  It allowed to
  publish metadata tables (named adverts, just a list of key
  value pairs really) in a globally visible name space.  For
  the example above, the streaming server could publich an
  URL at /home/andre/my_stream_urls/test-server.url, and
  attach meta data to it, such as:

    "url"     = "http://remote.host.net:1234/test"
    "desc"    = "my super service URL"
    "contact" = "merzky at cs.vu.nl"

  We used that service in a number of scenarios.


SAGA:
   
  in SAGA, a specification of an advert service would be
  trivial.  In fact, the complete spec would be:

  namespace saga
  {
    class advert implements-all name_space_entry
                 implements-all attributes
                 implements-all permissions { };
  
    class advert-dierctory 
                 implements-all name_space_directory
                 implements-all permissions { };
  }


Thats all for now, really - as usual, any feedback would be
welcome :-)

Cheers, Andre.
  

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| Andre Merzky                      | phon: +31 - 20 - 598 - 7759 |
| Vrije Universiteit Amsterdam (VU) | fax : +31 - 20 - 598 - 7653 |
| Dept. of Computer Science         | mail: merzky at cs.vu.nl       |
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