Service Name

• Establishing contact via a service name
  service name arbitrary, specific to an application
• Server publishes the pair (service name, port name)
  client asks for port name to a given service name
  "third party" = name server
• Name server routines optional in MPI-2
  possibly not supported in some implementations!
• Scope of service name:
  • where is it unique, which clients find it?
  • possible scopes e.g. job, machine, internet
  • implementation can use MPI_Info to limit the scope
• MPI routines:
  MPI_publish_name

  • server publishes portname corresponding to a servicename
  MPI_Unpublish_name

  • unpublishes service name
  MPI_Lookup_name

  • client asks for portname to a servicename
• Remarks on the example programs (lbpi_q.c, query.c, query.h)
  server: load balanced version of PI (LBPI) with additional query function
  client: asks server for state of pi computation
  server:

  • task 0: server, handels all communication with client
  • task 1: master, distributes work to slaves and collects results
  • task 2-n: slaves, compute partial results

  
  

  • master distinguishes between server and slaves through rank
  • master aborts at end of computation
  • unpublish at the end, otherwise error during next run
  client:

  • just a single task
  • gets state of computation and prints out intermediate result
  LAM implementation:

  • implements preliminary version of MPI-2 (different names etc.)
  • server task must have rank 0