zmq_setsockopt.txt 52.8 KB
Newer Older
1 2 3 4 5 6 7
zmq_setsockopt(3)
=================


NAME
----

Martin Lucina's avatar
Martin Lucina committed
8
zmq_setsockopt - set 0MQ socket options
9 10 11 12


SYNOPSIS
--------
Martin Lucina's avatar
Martin Lucina committed
13
*int zmq_setsockopt (void '*socket', int 'option_name', const void '*option_value', size_t 'option_len');*
14

Kobolog's avatar
Kobolog committed
15
Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE,
16
ZMQ_LINGER, ZMQ_ROUTER_HANDOVER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER,
17
ZMQ_XPUB_VERBOSE, ZMQ_XPUB_VERBOSER, ZMQ_REQ_CORRELATE,
18 19
ZMQ_REQ_RELAXED, ZMQ_SNDHWM and ZMQ_RCVHWM, only take effect for
subsequent socket bind/connects.
Pieter Hintjens's avatar
Pieter Hintjens committed
20 21 22

Specifically, security options take effect for subsequent bind/connect calls,
and can be changed at any time to affect subsequent binds and/or connects.
23 24 25

DESCRIPTION
-----------
Martin Lucina's avatar
Martin Lucina committed
26 27 28
The _zmq_setsockopt()_ function shall set the option specified by the
'option_name' argument to the value pointed to by the 'option_value' argument
for the 0MQ socket pointed to by the 'socket' argument. The 'option_len'
29 30 31
argument is the size of the option value in bytes. For options taking a value of
type "character string", the provided byte data should either contain no zero
bytes, or end in a single zero byte (terminating ASCII NUL character).
Martin Lucina's avatar
Martin Lucina committed
32

Martin Lucina's avatar
Martin Lucina committed
33
The following socket options can be set with the _zmq_setsockopt()_ function:
Martin Lucina's avatar
Martin Lucina committed
34 35 36 37


ZMQ_AFFINITY: Set I/O thread affinity
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Lucina's avatar
Martin Lucina committed
38 39
The 'ZMQ_AFFINITY' option shall set the I/O thread affinity for newly created
connections on the specified 'socket'.
Martin Lucina's avatar
Martin Lucina committed
40

41 42 43 44 45 46 47
Affinity determines which threads from the 0MQ I/O thread pool associated with
the socket's _context_ shall handle newly created connections.  A value of zero
specifies no affinity, meaning that work shall be distributed fairly among all
0MQ I/O threads in the thread pool. For non-zero values, the lowest bit
corresponds to thread 1, second lowest bit to thread 2 and so on.  For example,
a value of 3 specifies that subsequent connections on 'socket' shall be handled
exclusively by I/O threads 1 and 2.
Martin Lucina's avatar
Martin Lucina committed
48 49 50 51

See also linkzmq:zmq_init[3] for details on allocating the number of I/O
threads for a specific _context_.

52
[horizontal]
53
Option value type:: uint64_t
Martin Lucina's avatar
Martin Lucina committed
54 55 56 57 58
Option value unit:: N/A (bitmap)
Default value:: 0
Applicable socket types:: N/A


59 60 61 62 63 64
ZMQ_BACKLOG: Set maximum length of the queue of outstanding connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_BACKLOG' option shall set the maximum length of the queue of
outstanding peer connections for the specified 'socket'; this only applies to
connection-oriented transports. For details refer to your operating system
documentation for the 'listen' function.
Martin Lucina's avatar
Martin Lucina committed
65

66 67 68 69 70 71 72
[horizontal]
Option value type:: int
Option value unit:: connections
Default value:: 100
Applicable socket types:: all, only for connection-oriented transports.


73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
ZMQ_BINDTODEVICE: Set name of device to bind the socket to
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_BINDTODEVICE' option binds this socket to a particular device, eg.
an interface or VRF. If a socket is bound to an interface, only packets
received from that particular interface are processed by the socket. If device
is a VRF device, then subsequent binds/connects to that socket use addresses
in the VRF routing table.

NOTE: requires setting CAP_NET_RAW on the compiled program.

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP or UDP transports.


90 91
ZMQ_CONNECT_RID: Assign the next outbound connection id 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
92 93
This option name is now deprecated. Use ZMQ_CONNECT_ROUTING_ID instead. 
ZMQ_CONNECT_RID remains as an alias for now. 
94

95 96 97 98 99 100 101 102 103 104 105 106

ZMQ_CONNECT_ROUTING_ID: Assign the next outbound routing id 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_CONNECT_ROUTING_ID' option sets the peer id of the peer connected 
via the next zmq_connect() call, such that that connection is immediately ready for 
data transfer with the given routing id.  This option applies only to the first
subsequent call to zmq_connect(), zmq_connect() calls thereafter use the default 
connection behaviour. 

Typical use is to set this socket option ahead of each zmq_connect() call. 
Each connection MUST be assigned a unique routing id. Assigning a 
routing id that is already in use is not allowed. 
107 108

Useful when connecting ROUTER to ROUTER, or STREAM to STREAM, as it 
109
allows for immediate sending to peers. Outbound routing id framing requirements 
110 111
for ROUTER and STREAM sockets apply.

112 113 114
The routing id must be from 1 to 255 bytes long and MAY NOT start with 
a zero byte (such routing ids are reserved for internal use by the 0MQ 
infrastructure).
115 116 117 118 119 120 121 122

[horizontal]
Option value type:: binary data
Option value unit:: N/A
Default value:: NULL
Applicable socket types:: ZMQ_ROUTER, ZMQ_STREAM


123 124 125 126
ZMQ_CONFLATE: Keep only last message
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If set, a socket shall keep only one message in its inbound/outbound
queue, this message being the last message received/the last message
127
to be sent. Ignores 'ZMQ_RCVHWM' and 'ZMQ_SNDHWM' options. Does not
128 129
support multi-part messages, in particular, only one part of it is kept
in the socket internal queue.
Martin Lucina's avatar
Martin Lucina committed
130

131 132 133 134
NOTE: If recv is not called on the inbound socket, the queue and memory will
grow with each message received. Use linkzmq:zmq_getsockopt[3] with ZMQ_EVENTS
to trigger the conflation of the messages.

135
[horizontal]
136 137 138 139
Option value type:: int
Option value unit:: boolean
Default value:: 0 (false)
Applicable socket types:: ZMQ_PULL, ZMQ_PUSH, ZMQ_SUB, ZMQ_PUB, ZMQ_DEALER
Martin Lucina's avatar
Martin Lucina committed
140 141


KIU Shueng Chuan's avatar
KIU Shueng Chuan committed
142 143 144 145 146 147 148 149 150 151 152 153 154 155
ZMQ_CONNECT_TIMEOUT: Set connect() timeout
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets how long to wait before timing-out a connect() system call.
The connect() system call normally takes a long time before it returns a
time out error. Setting this option allows the library to time out the call
at an earlier interval.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: 0 (disabled)
Applicable socket types:: all, when using TCP transports.


156 157 158 159
ZMQ_CURVE_PUBLICKEY: Set CURVE public key
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the socket's long term public key. You must set this on CURVE client
sockets, see linkzmq:zmq_curve[7]. You can provide the key as 32 binary
160 161 162
bytes, or as a 40-character string encoded in the Z85 encoding format and
terminated in a null byte. The public key must always be used with the
matching secret key. To generate a public/secret key pair, use
163 164
linkzmq:zmq_curve_keypair[3]. To derive the public key from a secret key,
use linkzmq:zmq_curve_public[3].
165 166 167

NOTE: an option value size of 40 is supported for backwards compatibility,
though is deprecated.
Martin Lucina's avatar
Martin Lucina committed
168

169
[horizontal]
170
Option value type:: binary data or Z85 text string
171
Option value size:: 32 or 41
172 173 174 175 176 177 178 179 180
Default value:: NULL
Applicable socket types:: all, when using TCP transport


ZMQ_CURVE_SECRETKEY: Set CURVE secret key
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the socket's long term secret key. You must set this on both CURVE
client and server sockets, see linkzmq:zmq_curve[7]. You can provide the
key as 32 binary bytes, or as a 40-character string encoded in the Z85
181
encoding format and terminated in a null byte. To generate a public/secret
182 183
key pair, use linkzmq:zmq_curve_keypair[3]. To derive the public key from
a secret key, use linkzmq:zmq_curve_public[3].
184 185 186

NOTE: an option value size of 40 is supported for backwards compatibility,
though is deprecated.
187 188 189

[horizontal]
Option value type:: binary data or Z85 text string
190
Option value size:: 32 or 41
191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216
Default value:: NULL
Applicable socket types:: all, when using TCP transport


ZMQ_CURVE_SERVER: Set CURVE server role
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Defines whether the socket will act as server for CURVE security, see
linkzmq:zmq_curve[7]. A value of '1' means the socket will act as
CURVE server. A value of '0' means the socket will not act as CURVE
server, and its security role then depends on other option settings.
Setting this to '0' shall reset the socket security to NULL. When you
set this you must also set the server's secret key using the
ZMQ_CURVE_SECRETKEY option. A server socket does not need to know
its own public key.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: all, when using TCP transport


ZMQ_CURVE_SERVERKEY: Set CURVE server key
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the socket's long term server key. You must set this on CURVE client
sockets, see linkzmq:zmq_curve[7]. You can provide the key as 32 binary
217 218 219 220 221 222 223
bytes, or as a 40-character string encoded in the Z85 encoding format and
terminated in a null byte. This key must have been generated together with
the server's secret key. To generate a public/secret key pair, use
linkzmq:zmq_curve_keypair[3].

NOTE: an option value size of 40 is supported for backwards compatibility,
though is deprecated.
224 225 226

[horizontal]
Option value type:: binary data or Z85 text string
227
Option value size:: 32 or 41
228 229
Default value:: NULL
Applicable socket types:: all, when using TCP transport
Martin Lucina's avatar
Martin Lucina committed
230 231


232 233
ZMQ_GSSAPI_PLAINTEXT: Disable GSSAPI encryption
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Patrik Wenger's avatar
Patrik Wenger committed
234
Defines whether communications on the socket will be encrypted, see
235 236 237 238 239 240 241 242 243 244 245 246
linkzmq:zmq_gssapi[7]. A value of '1' means  that communications will be
plaintext.  A value of '0' means communications will be encrypted.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0 (false)
Applicable socket types:: all, when using TCP transport


ZMQ_GSSAPI_PRINCIPAL: Set name of GSSAPI principal
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
J.T. Conklin's avatar
J.T. Conklin committed
247
Sets the name of the principal for whom GSSAPI credentials should be acquired.
248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP transport


ZMQ_GSSAPI_SERVER: Set GSSAPI server role
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Defines whether the socket will act as server for GSSAPI security, see
linkzmq:zmq_gssapi[7]. A value of '1' means the socket will act as GSSAPI
server. A value of '0' means the socket will act as GSSAPI client.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0 (false)
Applicable socket types:: all, when using TCP transport


ZMQ_GSSAPI_SERVICE_PRINCIPAL: Set name of GSSAPI service principal
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
J.T. Conklin's avatar
J.T. Conklin committed
271
Sets the name of the principal of the GSSAPI server to which a GSSAPI client
272 273 274 275 276 277 278 279
intends to connect.

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP transport

280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308
ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE: Set name type of service principal
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the name type of the GSSAPI service principal.  A value of
'ZMQ_GSSAPI_NT_HOSTBASED' (0) means the name specified with
'ZMQ_GSSAPI_SERVICE_PRINCIPAL' is interpreted as a host based name.  A value
of 'ZMQ_GSSAPI_NT_USER_NAME' (1) means it is interpreted as a local user name.
A value of 'ZMQ_GSSAPI_NT_KRB5_PRINCIPAL' (2) means it is interpreted as an
unparsed principal name string (valid only with the krb5 GSSAPI mechanism).

[horizontal]
Option value type:: int
Option value unit:: 0, 1, 2
Default value:: 0 (ZMQ_GSSAPI_NT_HOSTBASED)
Applicable socket types:: all, when using TCP or IPC transport

ZMQ_GSSAPI_PRINCIPAL_NAMETYPE: Set name type of principal
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the name type of the GSSAPI principal.  A value of
'ZMQ_GSSAPI_NT_HOSTBASED' (0) means the name specified with
'ZMQ_GSSAPI_PRINCIPAL' is interpreted as a host based name.  A value of
'ZMQ_GSSAPI_NT_USER_NAME' (1) means it is interpreted as a local user name.
A value of 'ZMQ_GSSAPI_NT_KRB5_PRINCIPAL' (2) means it is interpreted as an
unparsed principal name string (valid only with the krb5 GSSAPI mechanism).

[horizontal]
Option value type:: int
Option value unit:: 0, 1, 2
Default value:: 0 (ZMQ_GSSAPI_NT_HOSTBASED)
Applicable socket types:: all, when using TCP or IPC transport
309

310 311 312 313
ZMQ_HANDSHAKE_IVL: Set maximum handshake interval
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_HANDSHAKE_IVL' option shall set the maximum handshake interval for
the specified 'socket'. Handshaking is the exchange of socket configuration
314
information (socket type, routing id, security) that occurs when a connection
315 316 317 318 319 320 321 322 323 324
is first opened, only for connection-oriented transports. If handshaking does
not complete within the configured time, the connection shall be closed.
The value 0 means no handshake time limit.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: 30000
Applicable socket types:: all but ZMQ_STREAM, only for connection-oriented transports

325

326 327 328 329 330 331 332 333 334 335 336 337
ZMQ_HEARTBEAT_IVL: Set interval between sending ZMTP heartbeats
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_HEARTBEAT_IVL' option shall set the interval between sending ZMTP heartbeats
for the specified 'socket'. If this option is set and is greater than 0, then a 'PING'
ZMTP command will be sent every 'ZMQ_HEARTBEAT_IVL' milliseconds.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: 0
Applicable socket types:: all, when using connection-oriented transports

338

339 340 341 342 343 344 345 346 347 348 349 350
ZMQ_HEARTBEAT_TIMEOUT: Set timeout for ZMTP heartbeats
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_HEARTBEAT_TIMEOUT' option shall set how long to wait before timing-out a
connection after sending a 'PING' ZMTP command and not receiving any traffic. This
option is only valid if 'ZMQ_HEARTBEAT_IVL' is also set, and is greater than 0. The
connection will time out if there is no traffic received after sending the 'PING'
command, but the received traffic does not have to be a 'PONG' command - any received
traffic will cancel the timeout.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
351
Default value:: 0 normally, ZMQ_HEARTBEAT_IVL if it is set
352 353
Applicable socket types:: all, when using connection-oriented transports

354

355 356 357 358 359
ZMQ_HEARTBEAT_TTL: Set the TTL value for ZMTP heartbeats
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_HEARTBEAT_TTL' option shall set the timeout on the remote peer for ZMTP
heartbeats. If this option is greater than 0, the remote side shall time out the
connection if it does not receive any more traffic within the TTL period. This option
360 361 362
does not have any effect if 'ZMQ_HEARTBEAT_IVL' is not set or is 0. Internally, this
value is rounded down to the nearest decisecond, any value less than 100 will have
no effect.
363 364

[horizontal]
365 366
Option value type:: int
Option value unit:: milliseconds
367
Default value:: 0
368
Maximum value:: 6553599 (which is 2^16-1 deciseconds)
369
Applicable socket types:: all, when using connection-oriented transports
370

371

372 373
ZMQ_IDENTITY: Set socket identity
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
374 375
This option name is now deprecated. Use ZMQ_ROUTING_ID instead. 
ZMQ_IDENTITY remains as an alias for now. 
376 377


378 379 380 381 382 383 384 385
ZMQ_IMMEDIATE: Queue messages only to completed connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By default queues will fill on outgoing connections even if the connection has
not completed. This can lead to "lost" messages on sockets with round-robin
routing (REQ, PUSH, DEALER). If this option is set to `1`, messages shall be
queued only to completed connections. This will cause the socket to block if
there are no other connections, but will prevent queues from filling on pipes
awaiting connection.
Martin Lucina's avatar
Martin Lucina committed
386

387
[horizontal]
388
Option value type:: int
389 390 391
Option value unit:: boolean
Default value:: 0 (false)
Applicable socket types:: all, only for connection-oriented transports.
Martin Lucina's avatar
Martin Lucina committed
392 393


394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415
ZMQ_INVERT_MATCHING: Invert message filtering
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Reverses the filtering behavior of PUB-SUB sockets, when set to 1.

On 'PUB' and 'XPUB' sockets, this causes messages to be sent to all
connected sockets 'except' those subscribed to a prefix that matches
the message. On 'SUB' sockets, this causes only incoming messages that
do 'not' match any of the socket's subscriptions to be received by the user.

Whenever 'ZMQ_INVERT_MATCHING' is set to 1 on a 'PUB' socket, all 'SUB'
sockets connecting to it must also have the option set to 1. Failure to
do so will have the 'SUB' sockets reject everything the 'PUB' socket sends
them. 'XSUB' sockets do not need to do this because they do not filter
incoming messages.

[horizontal]
Option value type:: int
Option value unit:: 0,1
Default value:: 0
Applicable socket types:: ZMQ_PUB, ZMQ_XPUB, ZMQ_SUB


416 417 418 419 420 421
ZMQ_IPV6: Enable IPv6 on socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Set the IPv6 option for the socket. A value of `1` means IPv6 is
enabled on the socket, while `0` means the socket will use only IPv4.
When IPv6 is enabled the socket will connect to, or accept connections
from, both IPv4 and IPv6 hosts.
Martin Lucina's avatar
Martin Lucina committed
422

423
[horizontal]
424
Option value type:: int
425 426 427
Option value unit:: boolean
Default value:: 0 (false)
Applicable socket types:: all, when using TCP transports.
428

429

430 431
ZMQ_LINGER: Set linger period for socket shutdown
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
432 433
The 'ZMQ_LINGER' option shall set the linger period for the specified 'socket'.
The linger period determines how long pending messages which have yet to be
434 435
sent to a peer shall linger in memory after a socket is disconnected with
linkzmq:zmq_disconnect[3] or closed with linkzmq:zmq_close[3], and further
436 437
affects the termination of the socket's context with linkzmq:zmq_ctx_term[3].
The following outlines the different behaviours:
438

439
* A value of '-1' specifies an infinite linger period. Pending
440
  messages shall not be discarded after a call to _zmq_disconnect()_ or
441
  _zmq_close()_; attempting to terminate the socket's context with _zmq_ctx_term()_
442
  shall block until all pending messages have been sent to a peer.
443 444

* The value of '0' specifies no linger period. Pending messages shall be
445
  discarded immediately after a call to _zmq_disconnect()_ or _zmq_close()_.
446 447

* Positive values specify an upper bound for the linger period in milliseconds.
448
  Pending messages shall not be discarded after a call to _zmq_disconnect()_ or
449
  _zmq_close()_; attempting to terminate the socket's context with _zmq_ctx_term()_
450 451
  shall block until either all pending messages have been sent to a peer, or the
  linger period expires, after which any pending messages shall be discarded.
452 453 454 455

[horizontal]
Option value type:: int
Option value unit:: milliseconds
456
Default value:: -1 (infinite)
457 458 459
Applicable socket types:: all


460 461 462 463 464 465 466 467 468 469
ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Limits the size of the inbound message. If a peer sends a message larger than
ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means 'no limit'.

[horizontal]
Option value type:: int64_t
Option value unit:: bytes
Default value:: -1
Applicable socket types:: all
470

471

472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491
ZMQ_METADATA: Add application metadata properties to a socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The _ZMQ_METADATA_ option shall add application metadata to the specified _socket_,
the metadata is exchanged with peers during connection setup. A metadata property is
specfied as a string, delimited by a colon, starting with the metadata _property_
followed by the metadata value, for example "X-key:value".
_Property_ names are restrited to maximum 255 characters and must be prefixed by "X-".
Multiple application metadata properties can be added to a socket by executing zmq_setsockopt()
multiple times. As the argument is a null-terminated string, binary data must be encoded
before it is added e.g. using Z85 (linkzmq:zmq_z85_encode[3]).

NOTE: in DRAFT state, not yet available in stable releases.

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all


492 493 494 495 496
ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the time-to-live field in every multicast packet sent from this socket.
The default is 1 which means that the multicast packets don't leave the local
network.
497 498 499

[horizontal]
Option value type:: int
500 501 502
Option value unit:: network hops
Default value:: 1
Applicable socket types:: all, when using multicast transports
503 504


505 506 507 508 509 510 511 512 513 514 515 516 517 518 519
ZMQ_MULTICAST_MAXTPDU: Maximum transport data unit size for multicast packets
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the maximum transport data unit size used for outbound multicast
packets.

This must be set at or below the minimum Maximum Transmission Unit (MTU) for
all network paths over which multicast reception is required.

[horizontal]
Option value type:: int
Option value unit:: bytes
Default value:: 1500
Applicable socket types:: all, when using multicast transports


520 521 522 523 524 525
ZMQ_PLAIN_PASSWORD: Set PLAIN security password
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the password for outgoing connections over TCP or IPC. If you set this
to a non-null value, the security mechanism used for connections shall be
PLAIN, see linkzmq:zmq_plain[7]. If you set this to a null value, the security
mechanism used for connections shall be NULL, see linkzmq:zmq_null[3].
526

527 528 529 530 531 532 533 534 535 536 537 538 539 540
[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP transport


ZMQ_PLAIN_SERVER: Set PLAIN server role
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Defines whether the socket will act as server for PLAIN security, see
linkzmq:zmq_plain[7]. A value of '1' means the socket will act as
PLAIN server. A value of '0' means the socket will not act as PLAIN
server, and its security role then depends on other option settings.
Setting this to '0' shall reset the socket security to NULL.
541 542 543

[horizontal]
Option value type:: int
544 545 546
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: all, when using TCP transport
547 548


549 550 551 552 553 554 555 556 557 558 559 560 561 562
ZMQ_PLAIN_USERNAME: Set PLAIN security username
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the username for outgoing connections over TCP or IPC. If you set this
to a non-null value, the security mechanism used for connections shall be
PLAIN, see linkzmq:zmq_plain[7]. If you set this to a null value, the security
mechanism used for connections shall be NULL, see linkzmq:zmq_null[3].

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP transport


563
ZMQ_USE_FD: Set the pre-allocated socket file descriptor
564
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584
When set to a positive integer value before zmq_bind is called on the socket,
the socket shall use the corresponding file descriptor for connections over
TCP or IPC instead of allocating a new file descriptor.
Useful for writing systemd socket activated services. If set to -1 (default),
a new file descriptor will be allocated instead (default behaviour).

NOTE: if set after calling zmq_bind, this option shall have no effect.
NOTE: the file descriptor passed through MUST have been ran through the "bind"
      and "listen" system calls beforehand. Also, socket option that would
      normally be passed through zmq_setsockopt like TCP buffers length,
      IP_TOS or SO_REUSEADDR MUST be set beforehand by the caller, as they
      must be set before the socket is bound.

[horizontal]
Option value type:: int
Option value unit:: file descriptor
Default value:: -1
Applicable socket types:: all bound sockets, when using IPC or TCP transport


585 586 587 588 589 590 591 592 593 594
ZMQ_PROBE_ROUTER: bootstrap connections to ROUTER sockets
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When set to 1, the socket will automatically send an empty message when a
new connection is made or accepted. You may set this on REQ, DEALER, or
ROUTER sockets connected to a ROUTER socket. The application must filter
such empty messages. The ZMQ_PROBE_ROUTER option in effect provides the
ROUTER application with an event signaling the arrival of a new peer.

NOTE: do not set this option on a socket that talks to any other socket
types: the results are undefined.
595 596 597

[horizontal]
Option value type:: int
598 599 600
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_ROUTER, ZMQ_DEALER, ZMQ_REQ
601

602

603 604 605 606 607 608 609 610 611 612
ZMQ_RATE: Set multicast data rate
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RATE' option shall set the maximum send or receive data rate for
multicast transports such as linkzmq:zmq_pgm[7] using the specified 'socket'.

[horizontal]
Option value type:: int
Option value unit:: kilobits per second
Default value:: 100
Applicable socket types:: all, when using multicast transports
613

614 615 616 617

ZMQ_RCVBUF: Set kernel receive buffer size
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RCVBUF' option shall set the underlying kernel receive buffer size for
618
the 'socket' to the specified size in bytes.  A value of -1 means leave the
619 620
OS default unchanged. For details refer to your operating system documentation
for the 'SO_RCVBUF' socket option.
621 622

[horizontal]
623
Option value type:: int
624
Option value unit:: bytes
625
Default value:: -1
626 627
Applicable socket types:: all

628

629 630 631 632 633 634 635
ZMQ_RCVHWM: Set high water mark for inbound messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RCVHWM' option shall set the high water mark for inbound messages on
the specified 'socket'. The high water mark is a hard limit on the maximum
number of outstanding messages 0MQ shall queue in memory for any single peer
that the specified 'socket' is communicating with. A value of zero means no
limit.
636

637 638 639 640 641
If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, 0MQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in linkzmq:zmq_socket[3] for details on the exact action taken for each socket
type.
642 643 644

[horizontal]
Option value type:: int
645 646 647
Option value unit:: messages
Default value:: 1000
Applicable socket types:: all
648

649

650 651 652 653 654 655 656 657 658 659 660 661 662 663 664
ZMQ_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the timeout for receive operation on the socket. If the value is `0`,
_zmq_recv(3)_ will return immediately, with a EAGAIN error if there is no
message to receive. If the value is `-1`, it will block until a message is
available. For all other values, it will wait for a message for that amount
of time before returning with an EAGAIN error.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: -1 (infinite)
Applicable socket types:: all


665 666 667 668 669 670
ZMQ_RECONNECT_IVL: Set reconnection interval
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RECONNECT_IVL' option shall set the initial reconnection interval for
the specified 'socket'.  The reconnection interval is the period 0MQ
shall wait between attempts to reconnect disconnected peers when using
connection-oriented transports. The value -1 means no reconnection.
671

672 673
NOTE: The reconnection interval may be randomized by 0MQ to prevent
reconnection storms in topologies with a large number of peers per socket.
674 675 676 677

[horizontal]
Option value type:: int
Option value unit:: milliseconds
678 679
Default value:: 100
Applicable socket types:: all, only for connection-oriented transports
680 681


682 683 684 685 686 687 688 689
ZMQ_RECONNECT_IVL_MAX: Set maximum reconnection interval
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RECONNECT_IVL_MAX' option shall set the maximum reconnection interval
for the specified 'socket'.  This is the maximum period 0MQ shall wait between
attempts to reconnect. On each reconnect attempt, the previous interval shall be
doubled untill ZMQ_RECONNECT_IVL_MAX is reached. This allows for exponential
backoff strategy. Default value means no exponential backoff is performed and
reconnect interval calculations are only based on ZMQ_RECONNECT_IVL.
Steven McCoy's avatar
Steven McCoy committed
690

691
NOTE:  Values less than ZMQ_RECONNECT_IVL will be ignored.
Pieter Hintjens's avatar
Pieter Hintjens committed
692 693 694

[horizontal]
Option value type:: int
695 696 697
Option value unit:: milliseconds
Default value:: 0 (only use ZMQ_RECONNECT_IVL)
Applicable socket types:: all, only for connection-oriented transports
Pieter Hintjens's avatar
Pieter Hintjens committed
698 699


700 701 702 703 704 705
ZMQ_RECOVERY_IVL: Set multicast recovery interval
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_RECOVERY_IVL' option shall set the recovery interval for multicast
transports using the specified 'socket'. The recovery interval determines the
maximum time in milliseconds that a receiver can be absent from a multicast
group before unrecoverable data loss will occur.
Pieter Hintjens's avatar
Pieter Hintjens committed
706

707 708 709
CAUTION: Exercise care when setting large recovery intervals as the data
needed for recovery will be held in memory. For example, a 1 minute recovery
interval at a data rate of 1Gbps requires a 7GB in-memory buffer.
Steven McCoy's avatar
Steven McCoy committed
710 711 712

[horizontal]
Option value type:: int
713 714 715
Option value unit:: milliseconds
Default value:: 10000
Applicable socket types:: all, when using multicast transports
Steven McCoy's avatar
Steven McCoy committed
716 717


718 719
ZMQ_REQ_CORRELATE: match replies with requests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
720
The default behaviour of REQ sockets is to rely on the ordering of messages to
721 722 723 724 725
match requests and responses and that is usually sufficient. When this option
is set to 1, the REQ socket will prefix outgoing messages with an extra frame
containing a request id. That means the full message is (request id, 0,
user frames...). The REQ socket will discard all incoming messages that don't
begin with these two frames.
726 727 728

[horizontal]
Option value type:: int
729
Option value unit:: 0, 1
730
Default value:: 0
731
Applicable socket types:: ZMQ_REQ
732 733


734 735 736 737
ZMQ_REQ_RELAXED: relax strict alternation between request and reply
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By default, a REQ socket does not allow initiating a new request with
_zmq_send(3)_ until the reply to the previous one has been received.
738 739 740
When set to 1, sending another message is allowed and previous replies will
be discarded if any. The request-reply state machine is reset and a new
request is sent to the next available peer.
741

742 743 744
If set to 1, also enable ZMQ_REQ_CORRELATE to ensure correct matching of
requests and replies. Otherwise a late reply to an aborted request can be
reported as the reply to the superseding request.
745 746 747

[horizontal]
Option value type:: int
748 749 750
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_REQ
751

752

753 754 755
ZMQ_ROUTER_HANDOVER: handle duplicate client routing ids on ROUTER sockets
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If two clients use the same routing id when connecting to a ROUTER, the
Pieter Hintjens's avatar
Pieter Hintjens committed
756 757
results shall depend on the ZMQ_ROUTER_HANDOVER option setting. If that
is not set (or set to the default of zero), the ROUTER socket shall reject
758
clients trying to connect with an already-used routing id. If that option
Pieter Hintjens's avatar
Pieter Hintjens committed
759 760
is set to 1, the ROUTER socket shall hand-over the connection to the new
client and disconnect the existing one.
761

Pieter Hintjens's avatar
Pieter Hintjens committed
762
[horizontal]
763 764 765 766 767
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_ROUTER

768

769 770
ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
771
Sets the ROUTER socket behaviour when an unroutable message is encountered. A
772
value of `0` is the default and discards the message silently when it cannot be
773 774 775 776 777
routed or the peers SNDHWM is reached.  A value of `1` returns an
'EHOSTUNREACH' error code if the message cannot be routed or 'EAGAIN' error
code if the SNDHWM is reached and ZMQ_DONTWAIT was used. Without ZMQ_DONTWAIT
it will block until the SNDTIMEO is reached or a spot in the send queue opens
up.
778

779 780 781
When ZMQ_ROUTER_MANDATORY is set to `1`, 'ZMQ_POLLOUT' events will be generated
if one or more messages can be sent to at least one of the peers. If
ZMQ_ROUTER_MANDATORY is set to `0`, the socket will generate a 'ZMQ_POLLOUT'
782
event on every call to 'zmq_poll' resp. 'zmq_poller_wait_all'.
783

Kobolog's avatar
Kobolog committed
784 785
[horizontal]
Option value type:: int
786 787
Option value unit:: 0, 1
Default value:: 0
Kobolog's avatar
Kobolog committed
788 789 790
Applicable socket types:: ZMQ_ROUTER


791 792
ZMQ_ROUTER_RAW: switch ROUTER socket to raw mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Pieter Hintjens's avatar
Pieter Hintjens committed
793
Sets the raw mode on the ROUTER, when set to 1. When the ROUTER socket is in
794 795
raw mode, and when using the tcp:// transport, it will read and write TCP data
without 0MQ framing. This lets 0MQ applications talk to non-0MQ applications.
796
When using raw mode, you cannot set explicit identities, and the ZMQ_SNDMORE
797
flag is ignored when sending data messages. In raw mode you can close a specific
798
connection by sending it a zero-length message (following the routing id frame).
799

800 801
NOTE: This option is deprecated, please use ZMQ_STREAM sockets instead.

802 803 804 805 806 807 808
[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_ROUTER


809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830
ZMQ_ROUTING_ID: Set socket routing id
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_ROUTING_ID' option shall set the routing id of the specified 'socket'
when connecting to a ROUTER socket. 

A routing id must be at least one byte and at most 255 bytes long. Identities
starting with a zero byte are reserved for use by the 0MQ infrastructure.

If two clients use the same routing id when connecting to a ROUTER, the
results shall depend on the ZMQ_ROUTER_HANDOVER option setting. If that
is not set (or set to the default of zero), the ROUTER socket shall reject
clients trying to connect with an already-used routing id. If that option
is set to 1, the ROUTER socket shall hand-over the connection to the new
client and disconnect the existing one.

[horizontal]
Option value type:: binary data
Option value unit:: N/A
Default value:: NULL
Applicable socket types:: ZMQ_REQ, ZMQ_REP, ZMQ_ROUTER, ZMQ_DEALER.


831 832 833
ZMQ_SNDBUF: Set kernel transmit buffer size
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_SNDBUF' option shall set the underlying kernel transmit buffer size
834
for the 'socket' to the specified size in bytes.  A value of -1 means leave
835 836
the OS default unchanged. For details please refer to your operating system
documentation for the 'SO_SNDBUF' socket option.
837 838 839

[horizontal]
Option value type:: int
840
Option value unit:: bytes
841
Default value:: -1
842
Applicable socket types:: all
843 844


845 846 847 848 849 850 851
ZMQ_SNDHWM: Set high water mark for outbound messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_SNDHWM' option shall set the high water mark for outbound messages on
the specified 'socket'. The high water mark is a hard limit on the maximum
number of outstanding messages 0MQ shall queue in memory for any single peer
that the specified 'socket' is communicating with. A value of zero means no
limit.
852

853 854 855 856 857
If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, 0MQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in linkzmq:zmq_socket[3] for details on the exact action taken for each socket
type.
858

859
NOTE: 0MQ does not guarantee that the socket will accept as many as ZMQ_SNDHWM
860
messages, and the actual limit may be as much as 90% lower depending on the
861
flow of messages on the socket.
862 863 864

[horizontal]
Option value type:: int
865 866 867
Option value unit:: messages
Default value:: 1000
Applicable socket types:: all
868

869

870 871 872 873 874 875 876
ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the timeout for send operation on the socket. If the value is `0`,
_zmq_send(3)_ will return immediately, with a EAGAIN error if the message
cannot be sent. If the value is `-1`, it will block until the message is sent.
For all other values, it will try to send the message for that amount of time
before returning with an EAGAIN error.
877 878 879

[horizontal]
Option value type:: int
880 881 882
Option value unit:: milliseconds
Default value:: -1 (infinite)
Applicable socket types:: all
883 884


885 886 887 888 889 890 891 892 893 894 895 896 897 898 899
ZMQ_SOCKS_PROXY: Set SOCKS5 proxy address
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the SOCKS5 proxy address that shall be used by the socket for the TCP
connection(s). Does not support SOCKS5 authentication. If the endpoints are
domain names instead of addresses they shall not be resolved and they shall
be forwarded unchanged to the SOCKS proxy service in the client connection
request message (address type 0x03 domain name).

[horizontal]
Option value type:: character string
Option value unit:: N/A
Default value:: not set
Applicable socket types:: all, when using TCP transport


900 901 902 903 904
ZMQ_STREAM_NOTIFY: send connect and disconnect notifications
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Enables connect and disconnect notifications on a STREAM socket, when set
to 1. When notifications are enabled, the socket delivers a zero-length
message when a peer connects or disconnects.
905 906 907 908

[horizontal]
Option value type:: int
Option value unit:: 0, 1
909
Default value:: 1
910 911 912
Applicable socket types:: ZMQ_STREAM


913 914 915 916 917
ZMQ_SUBSCRIBE: Establish message filter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_SUBSCRIBE' option shall establish a new message filter on a 'ZMQ_SUB'
socket. Newly created 'ZMQ_SUB' sockets shall filter out all incoming messages,
therefore you should call this option to establish an initial message filter.
918

919 920 921 922 923
An empty 'option_value' of length zero shall subscribe to all incoming
messages. A non-empty 'option_value' shall subscribe to all messages beginning
with the specified prefix. Multiple filters may be attached to a single
'ZMQ_SUB' socket, in which case a message shall be accepted if it matches at
least one filter.
924 925

[horizontal]
926 927 928 929
Option value type:: binary data
Option value unit:: N/A
Default value:: N/A
Applicable socket types:: ZMQ_SUB
930 931


932 933 934 935
ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Override 'SO_KEEPALIVE' socket option (where supported by OS).
The default value of `-1` means to skip any overrides and leave it to OS default.
936 937

[horizontal]
938 939 940 941
Option value type:: int
Option value unit:: -1,0,1
Default value:: -1 (leave to OS default)
Applicable socket types:: all, when using TCP transports.
942 943


944 945 946 947
ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Override 'TCP_KEEPCNT' socket option (where supported by OS). The default
value of `-1` means to skip any overrides and leave it to OS default.
948 949

[horizontal]
950 951 952 953
Option value type:: int
Option value unit:: -1,>0
Default value:: -1 (leave to OS default)
Applicable socket types:: all, when using TCP transports.
954 955


956
ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPIDLE (or TCP_KEEPALIVE on some OS)
957
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
958
Override 'TCP_KEEPIDLE' (or 'TCP_KEEPALIVE' on some OS) socket option (where
959 960
supported by OS). The default value of `-1` means to skip any overrides and
leave it to OS default.
961 962

[horizontal]
963 964 965 966
Option value type:: int
Option value unit:: -1,>0
Default value:: -1 (leave to OS default)
Applicable socket types:: all, when using TCP transports.
967 968


969
ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option
970
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
971 972
Override 'TCP_KEEPINTVL' socket option(where supported by OS). The default
value of `-1` means to skip any overrides and leave it to OS default.
973 974 975

[horizontal]
Option value type:: int
976 977 978
Option value unit:: -1,>0
Default value:: -1 (leave to OS default)
Applicable socket types:: all, when using TCP transports.
979

980

981
ZMQ_TCP_MAXRT: Set TCP Maximum Retransmit Timeout
982
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
983
On OSes where it is supported, sets how long before an unacknowledged TCP
984 985 986 987
retransmit times out. The system normally attempts many TCP retransmits
following an exponential backoff strategy. This means that after a network
outage, it may take a long time before the session can be re-established.
Setting this option allows the timeout to happen at a shorter interval.
988 989 990 991 992 993 994 995

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: 0 (leave to OS default)
Applicable socket types:: all, when using TCP transports.


996 997 998 999 1000
ZMQ_TOS: Set the Type-of-Service on socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the ToS fields (Differentiated services (DS) and Explicit Congestion
Notification (ECN) field of the IP header. The ToS field is typically used
to specify a packets priority. The availability of this option is dependent
J.T. Conklin's avatar
J.T. Conklin committed
1001
on intermediate network equipment that inspect the ToS field and provide a
1002
path for low-delay, high-throughput, highly-reliable service, etc.
1003 1004 1005

[horizontal]
Option value type:: int
1006
Option value unit:: >0
1007
Default value:: 0
1008
Applicable socket types:: all, only for connection-oriented transports
1009 1010


1011 1012 1013 1014 1015 1016 1017
ZMQ_UNSUBSCRIBE: Remove message filter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'ZMQ_UNSUBSCRIBE' option shall remove an existing message filter on a
'ZMQ_SUB' socket. The filter specified must match an existing filter previously
established with the 'ZMQ_SUBSCRIBE' option. If the socket has several
instances of the same filter attached the 'ZMQ_UNSUBSCRIBE' option shall remove
only one instance, leaving the rest in place and functional.
1018 1019

[horizontal]
1020
Option value type:: binary data
1021
Option value unit:: N/A
1022 1023
Default value:: N/A
Applicable socket types:: ZMQ_SUB
1024 1025


1026 1027 1028
ZMQ_XPUB_VERBOSE: pass duplicate subscribe messages on XPUB socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the 'XPUB' socket behaviour on new duplicated subscriptions. If enabled,
1029
the socket passes all subscribe messages to the caller. If disabled,
1030 1031
only the first subscription to each filter will be passed. The default is 0
(disabled).
1032 1033 1034

[horizontal]
Option value type:: int
1035 1036 1037 1038 1039
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_XPUB


1040 1041 1042 1043 1044 1045
ZMQ_XPUB_VERBOSER: pass duplicate subscribe and unsubscribe messages on XPUB socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sets the 'XPUB' socket behaviour on new duplicated subscriptions and
unsubscriptions. If enabled, the socket passes all subscribe and unsubscribe
messages to the caller. If disabled, only the first subscription to each filter and
the last unsubscription from each filter will be passed. The default is 0
1046
(disabled).
1047 1048 1049

[horizontal]
Option value type:: int
1050 1051
Option value unit:: 0, 1
Default value:: 0
1052
Applicable socket types:: ZMQ_XPUB
1053

1054

1055 1056
ZMQ_XPUB_MANUAL: change the subscription handling to manual
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
Sets the 'XPUB' socket subscription handling mode manual/automatic.
A value of '0' is the default and subscription requests will be handled automatically.
A value of '1' will change the subscription requests handling to manual, 
with manual mode subscription requests are not added to the subscription list.
To add subscription the user need to call setsockopt with ZMQ_SUBSCRIBE on XPUB socket.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_XPUB

1069

1070 1071
ZMQ_XPUB_NODROP: do not silently drop messages if SENDHWM is reached
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1072
Sets the 'XPUB' socket behaviour to return error EAGAIN if SENDHWM is
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084
reached and the message could not be send. 

A value of `0` is the default and drops the message silently when the peers
SNDHWM is reached.  A value of `1` returns an 'EAGAIN' error code if the
SNDHWM is reached and ZMQ_DONTWAIT was used.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: ZMQ_XPUB, ZMQ_PUB

1085

1086 1087
ZMQ_XPUB_WELCOME_MSG: set welcome message that will be received by subscriber when connecting
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
Sets a welcome message the will be recieved by subscriber when connecting.
Subscriber must subscribe to the Welcome message before connecting.
Welcome message will also be sent on reconnecting.
For welcome message to work well user must poll on incoming subscription messages on the XPUB socket and handle them.

Use NULL and lenght of zero to disable welcome message.

[horizontal]
Option value type:: binary data
Option value unit:: N/A
Default value:: NULL
Applicable socket types:: ZMQ_XPUB
1100

1101

1102 1103
ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1104 1105
Sets the domain for ZAP (ZMQ RFC 27) authentication. A ZAP domain must be 
specified to enable authentication. When the ZAP domain is empty, which is 
1106 1107 1108
the default, ZAP authentication is disabled. This is not compatible with
previous versions of libzmq, so it can be controlled by ZMQ_ZAP_ENFORCE_DOMAIN
which for now is disabled by default.
1109
See http://rfc.zeromq.org/spec:27 for more details.
1110 1111 1112 1113

[horizontal]
Option value type:: character string
Option value unit:: N/A
1114
Default value:: empty
1115 1116 1117
Applicable socket types:: all, when using TCP transport


1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133
ZMQ_ZAP_ENFORCE_DOMAIN: Set ZAP domain handling to strictly adhere the RFC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ZAP (ZMQ RFC 27) authentication protocol specifies that a domain must
always be set. Older versions of libzmq did not follow the spec and allowed
an empty domain to be set.
This option can be used to enabled or disable the stricter, backward
incompatible behaviour. For now it is disabled by default, but in a future
version it will be enabled by default.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 0
Applicable socket types:: all, when using ZAP


1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231
ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Assign an arbitrary number of filters that will be applied for each new TCP
transport connection on a listening socket. If no filters are applied, then
the TCP transport allows connections from any IP address. If at least one
filter is applied then new connection source ip should be matched. To clear
all filters call zmq_setsockopt(socket, ZMQ_TCP_ACCEPT_FILTER, NULL, 0).
Filter is a null-terminated string with ipv6 or ipv4 CIDR.

NOTE: This option is deprecated, please use authentication via the ZAP API
and IP address whitelisting / blacklisting.

[horizontal]
Option value type:: binary data
Option value unit:: N/A
Default value:: no filters (allow from all)
Applicable socket types:: all listening sockets, when using TCP transports.


ZMQ_IPC_FILTER_GID: Assign group ID filters to allow new IPC connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all GID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_GID, NULL, 0).

NOTE: GID filters are only available on platforms supporting SO_PEERCRED or
LOCAL_PEERCRED socket options (currently only Linux and later versions of
OS X).

NOTE: This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.

[horizontal]
Option value type:: gid_t
Option value unit:: N/A
Default value:: no filters (allow from all)
Applicable socket types:: all listening sockets, when using IPC transports.


ZMQ_IPC_FILTER_PID: Assign process ID filters to allow new IPC connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all PID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_PID, NULL, 0).

NOTE: PID filters are only available on platforms supporting the SO_PEERCRED
socket option (currently only Linux).

NOTE: This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.

[horizontal]
Option value type:: pid_t
Option value unit:: N/A
Default value:: no filters (allow from all)
Applicable socket types:: all listening sockets, when using IPC transports.


ZMQ_IPC_FILTER_UID: Assign user ID filters to allow new IPC connections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all UID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_UID, NULL, 0).

NOTE: UID filters are only available on platforms supporting SO_PEERCRED or
LOCAL_PEERCRED socket options (currently only Linux and later versions of
OS X).

NOTE: This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.

[horizontal]
Option value type:: uid_t
Option value unit:: N/A
Default value:: no filters (allow from all)
Applicable socket types:: all listening sockets, when using IPC transports.


ZMQ_IPV4ONLY: Use IPv4-only on socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Set the IPv4-only option for the socket. This option is deprecated.
Please use the ZMQ_IPV6 option.

[horizontal]
Option value type:: int
Option value unit:: boolean
Default value:: 1 (true)
Applicable socket types:: all, when using TCP transports.

1232

Ilya Kulakov's avatar
Ilya Kulakov committed
1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280
ZMQ_VMCI_BUFFER_SIZE: Set buffer size of the VMCI socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The `ZMQ_VMCI_BUFFER_SIZE` option shall set the size of the underlying
buffer for the socket. Used during negotiation before the connection is established.

[horizontal]
Option value type:: uint64_t
Option value unit:: bytes
Default value:: 65546
Applicable socket types:: all, when using VMCI transport


ZMQ_VMCI_BUFFER_MIN_SIZE: Set min buffer size of the VMCI socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The `ZMQ_VMCI_BUFFER_MIN_SIZE` option shall set the min size of the underlying
buffer for the socket. Used during negotiation before the connection is established.

[horizontal]
Option value type:: uint64_t
Option value unit:: bytes
Default value:: 128
Applicable socket types:: all, when using VMCI transport


ZMQ_VMCI_BUFFER_MAX_SIZE: Set max buffer size of the VMCI socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The `ZMQ_VMCI_BUFFER_MAX_SIZE` option shall set the max size of the underlying
buffer for the socket. Used during negotiation before the connection is established.

[horizontal]
Option value type:: uint64_t
Option value unit:: bytes
Default value:: 262144
Applicable socket types:: all, when using VMCI transport


ZMQ_VMCI_CONNECT_TIMEOUT: Set connection timeout of the VMCI socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The `ZMQ_VMCI_CONNECT_TIMEOUT` option shall set connection timeout
for the socket.

[horizontal]
Option value type:: int
Option value unit:: milliseconds
Default value:: -1
Applicable socket types:: all, when using VMCI transport


1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
ZMQ_MULTICAST_LOOP: Control multicast local loopback
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For multicast UDP sender sockets this option sets whether the data
sent should be looped back on local listening sockets.

[horizontal]
Option value type:: int
Option value unit:: 0, 1
Default value:: 1
Applicable socket types:: ZMQ_RADIO, when using UDP multicast transport

1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309

ZMQ_ROUTER_NOTIFY: Send connect and disconnect notifications
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Enable connect and disconnect notifications on a ROUTER socket.
When enabled, the socket delivers a zero-length message (with routing-id
as first frame) when a peer connects or disconnects. It's possible
to notify both events for a peer by OR-ing the flag values. This option
only applies to stream oriented (tcp, ipc) transports.

NOTE: in DRAFT state, not yet available in stable releases.

[horizontal]
Option value type:: int
Option value unit:: 0, ZMQ_NOTIFY_CONNECT, ZMQ_NOTIFY_DISCONNECT, ZMQ_NOTIFY_CONNECT|ZMQ_NOTIFY_DISCONNECT
Default value:: 0
Applicable socket types:: ZMQ_ROUTER


1310 1311
RETURN VALUE
------------
Martin Lucina's avatar
Martin Lucina committed
1312
The _zmq_setsockopt()_ function shall return zero if successful. Otherwise it
Martin Lucina's avatar
Martin Lucina committed
1313
shall return `-1` and set 'errno' to one of the values defined below.
1314 1315 1316 1317

ERRORS
------
*EINVAL*::
Martin Lucina's avatar
Martin Lucina committed
1318 1319
The requested option _option_name_ is unknown, or the requested _option_len_ or
_option_value_ is invalid.
1320
*ETERM*::
Martin Lucina's avatar
Martin Lucina committed
1321
The 0MQ 'context' associated with the specified 'socket' was terminated.
1322 1323
*ENOTSOCK*::
The provided 'socket' was invalid.
1324 1325
*EINTR*::
The operation was interrupted by delivery of a signal.
1326

1327 1328 1329

EXAMPLE
-------
Martin Lucina's avatar
Martin Lucina committed
1330
.Subscribing to messages on a 'ZMQ_SUB' socket
1331
----
Martin Lucina's avatar
Martin Lucina committed
1332 1333
/* Subscribe to all messages */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
1334
assert (rc == 0);
Martin Lucina's avatar
Martin Lucina committed
1335 1336 1337 1338 1339 1340
/* Subscribe to messages prefixed with "ANIMALS.CATS" */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);
----

.Setting I/O thread affinity
----
Martin Lucina's avatar
Martin Lucina committed
1341
int64_t affinity;
Martin Lucina's avatar
Martin Lucina committed
1342
/* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
Martin Lucina's avatar
Martin Lucina committed
1343
affinity = 1;
1344
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
Martin Lucina's avatar
Martin Lucina committed
1345 1346 1347 1348
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5555");
assert (rc);
/* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
Martin Lucina's avatar
Martin Lucina committed
1349
affinity = 2;
1350
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
Martin Lucina's avatar
Martin Lucina committed
1351
assert (rc);
1352
rc = zmq_bind (socket, "tcp://lo:5556");
Martin Lucina's avatar
Martin Lucina committed
1353
assert (rc);
1354 1355 1356 1357 1358
----


SEE ALSO
--------
Martin Lucina's avatar
Martin Lucina committed
1359
linkzmq:zmq_getsockopt[3]
1360
linkzmq:zmq_socket[3]
1361 1362
linkzmq:zmq_plain[7]
linkzmq:zmq_curve[7]
1363 1364
linkzmq:zmq[7]

1365

1366 1367
AUTHORS
-------
1368 1369
This page was written by the 0MQ community. To make a change please
read the 0MQ Contribution Policy at <http://www.zeromq.org/docs:contributing>.