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NAME

       MPI_Publish_name - Publishes a service name associated with a port

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Publish_name(char *service_name, MPI_Info info,
            char *port_name)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_PUBLISH_NAME(SERVICE_NAME, INFO, PORT_NAME, IERROR)
            CHARACTER*(*)  SERVICE_NAME, PORT_NAME
            INTEGER        INFO, IERROR

C++ Syntax

       #include <mpi.h>
       void MPI::Publish_name(const char* service_name, const MPI::Info& info,
            const char* port_name)

INPUT PARAMETERS

       service_name  A service name (string).

       info          Options to the name service functions (handle).

       port_name     A port name (string).

OUTPUT PARAMETER

       IERROR        Fortran only: Error status (integer).

DESCRIPTION

       This  routine  publishes  the pair (service_name, port_name) so that an
       application may retrieve  port_name  by  calling  MPI_Lookup_name  with
       service_name  as  an  argument.  It  is  an  error  to publish the same
       service_name twice, or  to  use  a  port_name  argument  that  was  not
       previously opened by the calling process via a call to MPI_Open_port.

INFO ARGUMENTS

       The following keys for info are recognized:

       Key                   Type      Description
       ---                   ----      -----------

       ompi_global_scope     bool      If set to true, publish the name in
                                       the global scope.  Publish in the local
                                       scope otherwise.  See the NAME SCOPE
                                       section for more details.

       bool  info  keys  are actually strings but are evaluated as follows: if
       the string value is a number, it is converted to an integer and cast to
       a boolean (meaning that zero integers are false and non-zero values are
       true).  If the string value is (case-insensitive) "yes" or "true",  the
       boolean  is  true.   If  the string value is (case-insensitive) "no" or
       "false",  the  boolean  is  false.   All  other   string   values   are
       unrecognized, and therefore false.

       If  no  info key is provided, the function will first check to see if a
       global server has been specified and is  available.  If  so,  then  the
       publish function will default to global scope first, followed by local.
       Otherwise, the data will default to publish with local scope.

NAME SCOPE

       Open MPI supports two name scopes: global and local. Local  scope  will
       place  the  specified  service/port pair in a data store located on the
       mpirun of the calling process' job. Thus,  data  published  with  local
       scope  will  only  be  accessible  to processes in jobs spawned by that
       mpirun - e.g., processes in  the  calling  process'  job,  or  in  jobs
       spawned via MPI_Comm_spawn.

       Global  scope  places  the  specified service/port pair in a data store
       located on a central server that is accessible to all jobs  running  in
       the  cluster or environment. Thus, data published with global scope can
       be accessed by multiple  mpiruns  and  used  for  MPI_Comm_Connect  and
       MPI_Comm_accept between jobs.

       Note  that  global  scope  operations  require both the presence of the
       central server and that the calling process be able to  communicate  to
       that  server.  MPI_Publish_name will return an error if global scope is
       specified and a global server is either  not  specified  or  cannot  be
       found.

       Open  MPI  provides a server called ompi-server to support global scope
       operations. Please refer  to  its  manual  page  for  a  more  detailed
       description of data store/lookup operations.

       As  an  example of the impact of these scoping rules, consider the case
       where a job has been started with mpirun -  call  this  job  "job1".  A
       process in job1 creates and publishes a service/port pair using a local
       scope. Open MPI will store this data in the data store within mpirun.

       A process in job1 (perhaps the same as did the publish, or perhaps some
       other  process  in  the job) subsequently calls MPI_Comm_spawn to start
       another job (call it "job2") under this  mpirun.  Since  the  two  jobs
       share  a  common  mpirun,  both  jobs  have access to local scope data.
       Hence, a process in job2 can perform an MPI_Lookup_name  with  a  local
       scope to retrieve the information.

       However,  assume another user starts a job using mpirun - call this job
       "job3". Because the service/port data published by job1 specified local
       scope,  processes  in job3 cannot access that data. In contrast, if the
       data had been published using global scope, then any  process  in  job3
       could  access the data, provided that mpirun was given knowledge of how
       to  contact  the  central  server  and  the  process  could   establish
       communication with it.

ERRORS

       Almost  all MPI routines return an error value; C routines as the value
       of the  function  and  Fortran  routines  in  the  last  argument.  C++
       functions  do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before  the  error  value is returned, the current MPI error handler is
       called. By default, this error handler aborts the MPI job,  except  for
       I/O   function   errors.   The   error  handler  may  be  changed  with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may  be  used  to cause error values to be returned. Note that MPI does
       not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

SEE ALSO

       MPI_Lookup_name
       MPI_Open_port



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