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 RPC_CLNT_CREATE 3NSL "Jul 25, 2015"
 NAME
rpc_clnt_create, clnt_control, clnt_create, clnt_create_timed,
clnt_create_vers, clnt_create_vers_timed, clnt_destroy, clnt_dg_create,
clnt_pcreateerror, clnt_raw_create, clnt_spcreateerror, clnt_tli_create,
clnt_tp_create, clnt_tp_create_timed, clnt_vc_create, rpc_createerr,
clnt_door_create - library routines for dealing with creation and manipulation
of CLIENT handles

 SYNOPSIS


#include <rpc/rpc.h>

bool_t clnt_control(CLIENT *clnt, const uint_t req, char *info);






CLIENT *clnt_create(const char *host, const rpcprog_t prognum,
 const rpcvers_t versnum, const char *nettype);






CLIENT *clnt_create_timed(const char *host, const rpcprog_t prognum,
 const rpcvers_t versnum, const char *nettype,
 const struct timeval *timeout);






CLIENT *clnt_create_vers (const char *host,
 const rpcprog_t prognum, rpcvers_t *vers_outp,
 const rpcvers_t vers_low, const rpcvers_t vers_high,
 const char *nettype);






CLIENT *clnt_create_vers_timed(const char *host,
 const rpcprog_t prognum, rpcvers_t *vers_outp,
 const rpcvers_t vers_low, const rpcvers_t vers_high,
 char *nettype, const struct timeval *timeout);






void clnt_destroy(CLIENT *clnt);






CLIENT *clnt_dg_create(const int fildes,
 const struct netbuf *svcaddr, const rpcprog_t prognum,
 const rpcvers_t versnum, const uint_t sendsz,
 const uint_t recsz);






void clnt_pcreateerror(const char *s);






CLIENT *clnt_raw_create(const rpcprog_t prognum,
 const rpcvers_t versnum);






char *clnt_spcreateerror(const char *s);






CLIENT *clnt_tli_create(const int fildes,
 const struct netconfig *netconf, const struct netbuf *svcaddr,
 const rpcprog_t prognum, const rpcvers_t versnum,
 const uint_t sendsz, const uint_t recsz);






CLIENT *clnt_tp_create(const char *host,
 const rpcprog_t prognum, const rpcvers_t versnum,
 const struct netconfig *netconf);






CLIENT *clnt_tp_create_timed(const char *host,
 const rpcprog_t prognum, const rpcvers_t versnum,
 const struct netconfig *netconf, const struct timeval *timeout);






CLIENT *clnt_vc_create(const int fildes,
 const struct netbuf *svcaddr, const rpcprog_t prognum,
 const rpcvers_t versnum, const uint_t sendsz,
 const uint_t recsz);






struct rpc_createerr rpc_createerr;






CLIENT *clnt_door_create(const rpcprog_t prognum,
 const rpcvers_t versnum, const uint_t sendsz);




 DESCRIPTION

RPC library routines allow C language programs to make procedure
calls on other machines across the network. First a CLIENT handle is
created and then the client calls a procedure to send a request to the server.
On receipt of the request, the server calls a dispatch routine to perform the
requested service, and then sends a reply.


These routines are MT-Safe. In the case of multithreaded applications, the
-mt option must be specified on the command line at compilation time.
When the -mt option is specified, rpc_createerr becomes a macro
that enables each thread to have its own rpc_createerr. See
threads(7).

 "Routines"

See rpc(3NSL) for the definition of the CLIENT data structure.
clnt_control()


A function macro to change or retrieve various information about a client
object. req indicates the type of operation, and info is a pointer
to the information. For both connectionless and connection-oriented transports,
the supported values of req and their argument types and what they do
are:

CLSET_TIMEOUT struct timeval * set total timeout
CLGET_TIMEOUT struct timeval * get total timeout



If the timeout is set using clnt_control(), the timeout argument passed
by clnt_call() is ignored in all subsequent calls. If the timeout value
is set to 0, clnt_control() immediately returns
RPC_TIMEDOUT. Set the timeout parameter to 0 for batching calls.

CLGET_SERVER_ADDR struct netbuf * get server's address
CLGET_SVC_ADDR struct netbuf * get server's address
CLGET_FD int * get associated file descriptor
CLSET_FD_CLOSE void close the file descriptor when
 destroying the client handle
 (see clnt_destroy())
CLSET_FD_NCLOSE void do not close the file
 descriptor when destroying the client handle
CLGET_VERS rpcvers_t get the RPC program's version
 number associated with the
 client handle
CLSET_VERS rpcvers_t set the RPC program's version
 number associated with the
 client handle. This assumes
 that the RPC server for this
 new version is still listening
 at the address of the previous
 version.
CLGET_XID uint32_t get the XID of the previous
 remote procedure call
CLSET_XID uint32_t set the XID of the next
 remote procedure call
CLGET_PROG rpcprog_t get program number
CLSET_PROG rpcprog_t set program number



The following operations are valid for connection-oriented transports only:

CLSET_IO_MODE rpciomode_t* set the IO mode used
 to send one-way requests. The argument for this operation
 can be either:
 - RPC_CL_BLOCKING all sending operations block
 until the underlying transport protocol has
 accepted requests. If you specify this argument
 you cannot use flush and getting and setting buffer
 size is meaningless.
 - RPC_CL_NONBLOCKING sending operations do not
 block and return as soon as requests enter the buffer.
 You can now use non-blocking I/O. The requests in the
 buffer are pending. The requests are sent to
 the server as soon as a two-way request is sent
 or a flush is done. You are responsible for flushing
 the buffer. When you choose RPC_CL_NONBLOCKING argument
 you have a choice of flush modes as specified by
 CLSET_FLUSH_MODE.
CLGET_IO_MODE rpciomode_t* get the current IO mode
CLSET_FLUSH_MODE rpcflushmode_t* set the flush mode.
 The flush mode can only be used in non-blocking I/O mode.
 The argument can be either of the following: 
 - RPC_CL_BESTEFFORT_FLUSH: All flushes send requests
 in the buffer until the transport end-point blocks.
 If the transport connection is congested, the call
 returns directly. 
 - RPC_CL_BLOCKING_FLUSH: Flush blocks until the
 underlying transport protocol accepts all pending
 requests into the queue.
CLGET_FLUSH_MODE rpcflushmode_t* get the current flush mode.
CLFLUSH rpcflushmode_t flush the pending requests.
 This command can only be used in non-blocking I/O mode.
 The flush policy depends on which of the following
 parameters is specified:
 - RPC_CL_DEFAULT_FLUSH, or NULL: The flush is done
 according to the current flush mode policy
 (see CLSET_FLUSH_MODE option).
 - RPC_CL_BESTEFFORT_FLUSH: The flush tries
 to send pending requests without blocking; the call
 returns directly. If the transport connection is
 congested, this call could return without the request
 being sent.
 - RPC_CL_BLOCKING_FLUSH: The flush sends all pending
 requests. This call will block until all the requests
 have been accepted by the transport layer.
CLSET_CONNMAXREC_SIZE int* set the buffer size.
 It is not possible to dynamically
 resize the buffer if it contains data.
 The default size of the buffer is 16 kilobytes.
CLGET_CONNMAXREC_SIZE int* get the current size of the
 buffer
CLGET_CURRENT_REC_SIZE int* get the size of
 the pending requests stored in the buffer. Use of this
 command is only recommended when you are in non-blocking
 I/O mode. The current size of the buffer is always zero
 when the handle is in blocking mode as the buffer is not
 used in this mode.



The following operations are valid for connectionless transports only:

CLSET_RETRY_TIMEOUT struct timeval * set the retry timeout
CLGET_RETRY_TIMEOUT struct timeval * get the retry timeout



The retry timeout is the time that RPC waits for the server to reply
before retransmitting the request.
clnt_control() returns TRUE on success and FALSE on failure.



clnt_create()


Generic client creation routine for program prognum and version
versnum. host identifies the name of the remote host where the
server is located. nettype indicates the class of transport protocol to
use. The transports are tried in left to right order in NETPATH variable
or in top to bottom order in the netconfig database.
clnt_create() tries all the transports of the nettype class
available from the NETPATH environment variable and the netconfig
database, and chooses the first successful one. A default timeout is set and
can be modified using clnt_control(). This routine returns NULL if
it fails. The clnt_pcreateerror() routine can be used to print the reason
for failure.
Note that clnt_create() returns a valid client handle even if the
particular version number supplied to clnt_create() is not registered
with the rpcbind service. This mismatch will be discovered by a
clnt_call later (see rpc_clnt_calls(3NSL)).



clnt_create_timed()


Generic client creation routine which is similar to clnt_create() but
which also has the additional parameter timeout that specifies the
maximum amount of time allowed for each transport class tried. In all other
respects, the clnt_create_timed() call behaves exactly like the
clnt_create() call.



clnt_create_vers()


Generic client creation routine which is similar to clnt_create() but
which also checks for the version availability. host identifies the name
of the remote host where the server is located. nettype indicates the
class transport protocols to be used. If the routine is successful it returns a
client handle created for the highest version between vers_low and
vers_high that is supported by the server. vers_outp is set to this
value. That is, after a successful return vers_low <= *vers_outp <=
vers_high. If no version between vers_low and vers_high is
supported by the server then the routine fails and returns NULL. A
default timeout is set and can be modified using clnt_control(). This
routine returns NULL if it fails. The clnt_pcreateerror() routine
can be used to print the reason for failure.
Note: clnt_create() returns a valid client handle even if the particular
version number supplied to clnt_create() is not registered with the
rpcbind service. This mismatch will be discovered by a clnt_call
later (see rpc_clnt_calls(3NSL)). However, clnt_create_vers() does
this for you and returns a valid handle only if a version within the range
supplied is supported by the server.



clnt_create_vers_timed()


Generic client creation routine similar to clnt_create_vers() but with
the additional parameter timeout, which specifies the maximum amount of
time allowed for each transport class tried. In all other respects, the
clnt_create_vers_timed() call behaves exactly like the
clnt_create_vers() call.



clnt_destroy()


A function macro that destroys the client's RPC handle. Destruction
usually involves deallocation of private data structures, including clnt
itself. Use of clnt is undefined after calling clnt_destroy(). If
the RPC library opened the associated file descriptor, or
CLSET_FD_CLOSE was set using clnt_control(), the file descriptor
will be closed.
The caller should call auth_destroy(clnt->cl_auth) (before
calling clnt_destroy()) to destroy the associated AUTH structure
(see rpc_clnt_auth(3NSL)).



clnt_dg_create()


This routine creates an RPC client for the remote program prognum
and version versnum; the client uses a connectionless transport. The
remote program is located at address svcaddr. The parameter fildes
is an open and bound file descriptor. This routine will resend the call message
in intervals of 15 seconds until a response is received or until the call times
out. The total time for the call to time out is specified by clnt_call()
(see clnt_call() in rpc_clnt_calls(3NSL)). The retry time out and
the total time out periods can be changed using clnt_control(). The user
may set the size of the send and receive buffers with the parameters
sendsz and recvsz; values of 0 choose suitable defaults. This
routine returns NULL if it fails.



clnt_pcreateerror()


Print a message to standard error indicating why a client RPC handle
could not be created. The message is prepended with the string s and a
colon, and appended with a newline.



clnt_raw_create()


This routine creates an RPC client handle for the remote program
prognum and version versnum. The transport used to pass messages to
the service is a buffer within the process's address space, so the
corresponding RPC server should live in the same address space; (see
svc_raw_create() in rpc_svc_create(3NSL)). This allows simulation
of RPC and measurement of RPC overheads, such as round trip times,
without any kernel or networking interference. This routine returns NULL
if it fails. clnt_raw_create() should be called after
svc_raw_create().



clnt_spcreateerror()


Like clnt_pcreateerror(), except that it returns a string instead of
printing to the standard error. A newline is not appended to the message in
this case.
Warning: returns a pointer to a buffer that is overwritten on each call. In
multithread applications, this buffer is implemented as thread-specific data.



clnt_tli_create()


This routine creates an RPC client handle for the remote program
prognum and version versnum. The remote program is located at
address svcaddr. If svcaddr is NULL and it is
connection-oriented, it is assumed that the file descriptor is connected. For
connectionless transports, if svcaddr is NULL,
RPC_UNKNOWNADDR error is set. fildes is a file descriptor which may
be open, bound and connected. If it is RPC_ANYFD, it opens a file
descriptor on the transport specified by netconf. If fildes is
RPC_ANYFD and netconf is NULL, a RPC_UNKNOWNPROTO error
is set. If fildes is unbound, then it will attempt to bind the
descriptor. The user may specify the size of the buffers with the parameters
sendsz and recvsz; values of 0 choose suitable defaults.
Depending upon the type of the transport (connection-oriented or
connectionless), clnt_tli_create() calls appropriate client creation
routines. This routine returns NULL if it fails. The
clnt_pcreateerror() routine can be used to print the reason for failure.
The remote rpcbind service (see rpcbind(8)) is not consulted for
the address of the remote service.



clnt_tp_create()


Like clnt_create() except clnt_tp_create() tries only one transport
specified through netconf.
clnt_tp_create() creates a client handle for the program prognum,
the version versnum, and for the transport specified by netconf.
Default options are set, which can be changed using clnt_control() calls.
The remote rpcbind service on the host host is consulted for the
address of the remote service. This routine returns NULL if it fails. The
clnt_pcreateerror() routine can be used to print the reason for failure.



clnt_tp_create_timed()


Like clnt_tp_create() except clnt_tp_create_timed() has the extra
parameter timeout which specifies the maximum time allowed for the
creation attempt to succeed. In all other respects, the
clnt_tp_create_timed() call behaves exactly like the
clnt_tp_create() call.



clnt_vc_create()


This routine creates an RPC client for the remote program prognum
and version versnum; the client uses a connection-oriented transport. The
remote program is located at address svcaddr. The parameter fildes
is an open and bound file descriptor. The user may specify the size of the send
and receive buffers with the parameters sendsz and recvsz; values
of 0 choose suitable defaults. This routine returns NULL if it
fails.
The address svcaddr should not be NULL and should point to the
actual address of the remote program. clnt_vc_create() does not consult
the remote rpcbind service for this information.



rpc_createerr


A global variable whose value is set by any RPC client handle creation
routine that fails. It is used by the routine clnt_pcreateerror() to
print the reason for the failure.
In multithreaded applications, rpc_createerr becomes a macro which
enables each thread to have its own rpc_createerr.



clnt_door_create()


This routine creates an RPC client handle over doors for the given program
prognum and version versnum. Doors is a transport mechanism that
facilitates fast data transfer between processes on the same machine. The user
may set the size of the send buffer with the parameter sendsz. If
sendsz is 0, the corresponding default buffer size is 16 Kbyte. The
clnt_door_create() routine returns NULL if it fails and sets a
value for rpc_createerr.




 ATTRIBUTES

See attributes(7) for descriptions of the following attributes:






ATTRIBUTE TYPE ATTRIBUTE VALUE
Architecture All
Interface Stability Committed
MT-Level MT-Safe



 SEE ALSO

 rpc (3NSL),  rpc_clnt_auth (3NSL),  rpc_clnt_calls (3NSL),  rpc_svc_create (3NSL),  svc_raw_create (3NSL),  attributes (7),  threads (7),  rpcbind (8)