MPI_Publish_name(3)                Open MPI                MPI_Publish_name(3)



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





1.4.1                            Jan 14, 2010              MPI_Publish_name(3)
