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============================================================================================ 
Man Page: rmr_wh_open 
============================================================================================ 
 
RMR Library Functions 
============================================================================================ 
 
 
NAME 
-------------------------------------------------------------------------------------------- 
 
rmr_wh_open 
 
SYNOPSIS 
-------------------------------------------------------------------------------------------- 
 
 
:: 
  
 #include <rmr/rmr.h>
 void* rmr_wh_open( void* vctx, char* target )
 
 
 
DESCRIPTION 
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The rmr_wh_open function creates a direct link for sending, a 
wormhole, to another RMR based process. Sending messages 
through a wormhole requires that the connection be 
established overtly by the user application (via this 
function), and that the ID returned by rmr_wh_open be passed 
to the rmr_wh_send_msg function. 
 
*Target* is the *name* or *IP-address* combination of the 
processess that the wormhole should be connected to. *Vctx* 
is the RMR void context pointer that was returned by the 
rmr_init function. 
 
When invoked, this function immediatly attempts to connect to 
the target process. If the connection cannot be established, 
an error is returned to the caller, and no direct messages 
can be sent to the target. Once a wormhole is connected, the 
underlying transport mechanism (e.g. NNG) will provide 
reconnects should the connection be lost, however the 
handling of messages sent when a connection is broken is 
undetermined as each underlying transport mechanism may 
handle buffering and retries differently. 
 
RETURN VALUE 
-------------------------------------------------------------------------------------------- 
 
The rmr_wh_open function returns a type rmr_whid_t which must 
be passed to the rmr_wh_send_msg function when sending a 
message. The id may also be tested to determine success or 
failure of the connection by using the RMR_WH_CONNECTED macro 
and passing the ID as the parameter; a result of 1 indicates 
that the connection was esablished and that the ID is valid. 
 
ERRORS 
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The following error values are specifically set by this RMR 
function. In some cases the error message of a system call is 
propagated up, and thus this list might be incomplete. 
 
 
EINVAL 
   
  A parameter passed was not valid. 
 
EACCESS 
   
  The user application does not have the ability to 
  establish a wormhole to the indicated target (or maybe any 
  target). 
 
ECONNREFUSED 
   
  The connection was refused. 
 
 
EXAMPLE 
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:: 
  
    void*  rmc;
    rmr_whid_t wh;
    rmc = rmr_init( "43086", 4096, 0 ); // init context
    wh = rmr_wh_open( rmc, "localhost:6123" );
    if( !RMR_WH_CONNECTED( wh ) ) {
      fprintf( stderr, "unable to connect wormhole: %s\\n",
              strerror( errno ) );
    }
 
 
 
SEE ALSO 
-------------------------------------------------------------------------------------------- 
 
rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), 
rmr_get_rcvfd(3), rmr_payload_size(3), rmr_send_msg(3), 
rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), 
rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), 
rmr_mk_ring(3), rmr_ring_free(3), rmr_wh_close(3), 
rmr_wh_send_msg(3), rmr_wh_state(3)