.\" -*- nroff -*-
.\" Copyright 2013 Los Alamos National Security, LLC. All rights reserved.
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2007-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Comm_connect 3 "May 26, 2022" "4.1.4" "Open MPI"
.SH NAME
\fBMPI_Comm_connect \fP \- Establishes communication with a server.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Comm_connect(const char *\fIport_name\fP, MPI_Info \fIinfo\fP, int \fIroot\fP,
	MPI_Comm \fIcomm\fP, MPI_Comm *\fInewcomm\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_CONNECT(\fIPORT_NAME, INFO, ROOT, COMM, NEWCOMM, IERROR\fP)
	CHARACTER*(*)	\fIPORT_NAME\fP
	INTEGER		\fIINFO, ROOT, COMM, NEWCOMM, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Comm_connect(\fIport_name\fP, \fIinfo\fP, \fIroot\fP, \fIcomm\fP, \fInewcomm\fP, \fIierror\fP)
	CHARACTER(LEN=*), INTENT(IN) :: \fIport_name\fP
	TYPE(MPI_Info), INTENT(IN) :: \fIinfo\fP
	INTEGER, INTENT(IN) :: \fIroot\fP
	TYPE(MPI_Comm), INTENT(IN) :: \fIcomm\fP
	TYPE(MPI_Comm), INTENT(OUT) :: \fInewcomm\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
MPI::Intercomm MPI::Intracomm::Connect(const char* \fIport_name\fP,
	const MPI::Info& \fIinfo\fP, int \fIroot\fP) const

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
port_name
Port name (string, used only on \fIroot\fP).
.TP 1i
info
Options given by root for the connect (handle, used only on root). No options currently supported.
.TP 1i
root
Rank in \fIcomm\fP of root node (integer).
.TP 1i
comm
Intracommunicator over which call is collective (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
newcomm
Intercommunicator with client as remote group (handle)
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_Comm_connect establishes communication with a server specified by \fIport_name\fP. It is collective over the calling communicator and returns an intercommunicator in which the remote group participated in an MPI_Comm_accept. The MPI_Comm_connect call must only be called after the MPI_Comm_accept call has been made by the MPI job acting as the server.
.sp
If the named port does not exist (or has been closed), MPI_Comm_connect raises an error of class MPI_ERR_PORT.
.sp
MPI provides no guarantee of fairness in servicing connection attempts. That is, connection attempts are not necessarily satisfied in the order in which they were initiated, and competition from other connection attempts may prevent a particular connection attempt from being satisfied.

The \fIport_name\fP parameter is the address of the server. It must be the same as the name returned by MPI_Open_port on the server.


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

.SH SEE ALSO
MPI_Comm_accept
MPI_Open_port
.br