OpenMPI publish name example as explained here : http://tinyurl.com/gnba6zj

name-client.c

/*!
 * 
 *  OpenMPI nameserver example 
 * 
 * client that looks up name from nameserver then connects to that server
 * 
 * */

#include "mpi.h" 
#include "stdio.h"
#include "string.h"

#define  MAX_DATA 50
/*!
 \brief How to execute mpi name server 
 mpirun -np 1  ompi-server --no-daemonize -r + &
 * 
 * Success looks like this :
 * 
	"server available at 3653042176.0;tcp://192.168.10.191:52434+3653042177.0;tcp://192.168.10.191:48880:300"

*/
int main( int argc, char **argv ) 
{ 
    MPI_Comm server; 
    double buf[MAX_DATA]; 
    char port_name[MPI_MAX_PORT_NAME]; 
    int tag = 0;
		int done = 0;
		int n;
		double  * p;
		
		buf[0] = 25.5;
		buf[1] = 26.5;
		buf[2] = 27.5;
		n = 2;
		
    MPI_Init( &argc, &argv ); 
    //strcpy(port_name, argv[1] );/* assume server's name is cmd-line arg */ 
		
		fprintf(stderr, "looking up  server ... \n");
		// second command line parameter is the name of server to lookup
    MPI_Lookup_name( "ocean", MPI_INFO_NULL, port_name); 

		// connect to name and place data into server
    MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,  &server ); 
    // aim p at first double entry
		p = buf;
    while (!done) 
    { 

        tag = 2; /* Action to perform */ 
        MPI_Send( (void *) p, 1, MPI_DOUBLE, 0, tag, server ); 
        /* etc */ 
        n--;
        p++;
        if ( n < 0) done = 1; 
        
    } 
    MPI_Send( buf, 0, MPI_DOUBLE, 0, 1, server ); 
    MPI_Comm_disconnect( &server ); 
    MPI_Finalize(); 
    return 0; 
} 

/* client side lookup request
    MPI_Lookup_name("ocean", MPI_INFO_NULL, port_name); 
    MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_SELF,  
                      &intercomm); 


*/

name-server.c

/*!
 * 
 *  OpenMPI nameserver example 
 * 
 * server that publishes name to nameserver then awaits client connections
 * 
 * */

#include "mpi.h" 
#include "stdio.h"
#include "string.h"

#define  MAX_DATA 50

/*!
 \brief How to execute mpi name server 
 mpirun -np 1  ompi-server --no-daemonize -r + &
 * 
 * Success looks like this :
 * 
	"server available at 3653042176.0;tcp://192.168.10.191:52434+3653042177.0;tcp://192.168.10.191:48880:300"

*/

int main( int argc, char **argv ) 
{ 
    MPI_Comm client; 
    MPI_Status status; 
    char port_name[MPI_MAX_PORT_NAME]; 
    double buf[MAX_DATA]; 
    int    size, again; 
		MPI_Info info;
	  double * p; 
 
    MPI_Init( &argc, &argv ); 
    MPI_Comm_size(MPI_COMM_WORLD, &size); 
    if (size != 1) error( "Server too big"); 
    

    
    MPI_Open_port(MPI_INFO_NULL, port_name); 
    printf("server available at %s\n",port_name); 
    
   	MPI_Info_create(&info);
		MPI_Info_set(info, "ompi_global_scope", "true");    
		// publish to name server with global scope info 
    MPI_Publish_name("ocean", info, port_name);
        
    while (1) 
    { 
			// accept clients
        MPI_Comm_accept( port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,  &client ); 
        again = 1; 
        while (again) 
        { 
            MPI_Recv( buf, MAX_DATA, MPI_DOUBLE,  MPI_ANY_SOURCE, MPI_ANY_TAG, client, &status ); 
            switch (status.MPI_TAG) 
            { 
                case 0: 
									MPI_Unpublish_name("ocean", MPI_INFO_NULL, port_name);
									MPI_Comm_free( &client ); 
                  MPI_Close_port(port_name); 
                  MPI_Finalize(); 
                  return 0; 
                case 1: 
									MPI_Comm_disconnect( &client ); 
									again = 0; 
                  break; 
                case 2: /* do something */ 
									p = (double *) buf;
									fprintf(stderr, " we got a client's data: %f\n",  *p);
									break;
                default: 
                  /* Unexpected message type */ 
                  // radical original version aborted everything...
                  ;//MPI_Abort( MPI_COMM_WORLD, 1 ); 
             } 
        } 
     } 
} 

/* 

    MPI_Open_port(MPI_INFO_NULL, port_name); 
    MPI_Publish_name("ocean", MPI_INFO_NULL, port_name); 
 
    MPI_Comm_accept(port_name, MPI_INFO_NULL, 0, MPI_COMM_SELF, &intercomm); 
    // do something with intercomm 
    MPI_Unpublish_name("ocean", MPI_INFO_NULL, port_name); 

*/