NAME¶
zmq_setsockopt - set 0MQ socket options
SYNOPSIS¶
int zmq_setsockopt (void *socket, int
option_name , const void
*option_value, size_t
option_len);
Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE,
ZMQ_LINGER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER, ZMQ_XPUB_VERBOSE,
ZMQ_REQ_CORRELATE, and ZMQ_REQ_RELAXED, only take effect for subsequent socket
bind/connects.
Specifically, security options take effect for subsequent bind/connect calls,
and can be changed at any time to affect subsequent binds and/or connects.
DESCRIPTION¶
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 argument is the size of the option value in bytes.
The following socket options can be set with the
zmq_setsockopt()
function:
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.
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
zmq_socket(3) for details on the exact action taken for
each socket type.
Note
0MQ does not guarantee that the socket will accept as many as ZMQ_SNDHWM
messages, and the actual limit may be as much as 60-70% lower depending on the
flow of messages on the socket.
| Option value type |
int |
| Option value unit |
messages |
| Default value |
1000 |
| Applicable socket types |
all |
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.
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
zmq_socket(3) for details on the exact action taken for
each socket type.
| Option value type |
int |
| Option value unit |
messages |
| Default value |
1000 |
| Applicable socket types |
all |
ZMQ_AFFINITY: Set I/O thread affinity¶
The
ZMQ_AFFINITY option shall set the I/O thread affinity for newly
created connections on the specified
socket.
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.
See also
zmq_init(3) for details on allocating the number of I/O threads
for a specific
context.
| Option value type |
uint64_t |
| Option value unit |
N/A (bitmap) |
| Default value |
0 |
| Applicable socket types |
N/A |
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.
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.
| Option value type |
binary data |
| Option value unit |
N/A |
| Default value |
N/A |
| Applicable socket types |
ZMQ_SUB |
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.
| Option value type |
binary data |
| Option value unit |
N/A |
| Default value |
N/A |
| Applicable socket types |
ZMQ_SUB |
ZMQ_IDENTITY: Set socket identity¶
The
ZMQ_IDENTITY option shall set the identity of the specified
socket when connecting to a ROUTER socket. The identity should be from
1 to 255 bytes long and MAY NOT start with binary zero.
If two clients use the same identity when connecting to a ROUTER, the ROUTER
socket shall accept only the first such client and reject the others.
| Option value type |
binary data |
| Option value unit |
N/A |
| Default value |
NULL |
| Applicable socket types |
ZMQ_REQ, ZMQ_REP, ZMQ_ROUTER, ZMQ_DEALER. |
ZMQ_RATE: Set multicast data rate¶
The
ZMQ_RATE option shall set the maximum send or receive data rate for
multicast transports such as
zmq_pgm(7) using the specified
socket.
| Option value type |
int |
| Option value unit |
kilobits per second |
| Default value |
100 |
| Applicable socket types |
all, when using multicast transports |
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.
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.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
10000 |
| Applicable socket types |
all, when using multicast transports |
ZMQ_SNDBUF: Set kernel transmit buffer size¶
The
ZMQ_SNDBUF option shall set the underlying kernel transmit buffer
size for the
socket to the specified size in bytes. A value of zero
means leave the OS default unchanged. For details please refer to your
operating system documentation for the
SO_SNDBUF socket option.
| Option value type |
int |
| Option value unit |
bytes |
| Default value |
0 |
| Applicable socket types |
all |
ZMQ_RCVBUF: Set kernel receive buffer size¶
The
ZMQ_RCVBUF option shall set the underlying kernel receive buffer size
for the
socket to the specified size in bytes. A value of zero means
leave the OS default unchanged. For details refer to your operating system
documentation for the
SO_RCVBUF socket option.
| Option value type |
int |
| Option value unit |
bytes |
| Default value |
0 |
| Applicable socket types |
all |
ZMQ_LINGER: Set linger period for socket shutdown¶
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 sent to a peer shall linger in memory after a socket is closed
with
zmq_close(3), and further affects the termination of the
socket’s context with
zmq_term(3). The following outlines the
different behaviours:
•The default value of -1 specifies an
infinite linger period. Pending messages shall not be discarded after a call
to zmq_close(); attempting to terminate the socket’s context
with zmq_term() shall block until all pending messages have been sent
to a peer.
•The value of 0 specifies no linger period.
Pending messages shall be discarded immediately when the socket is closed with
zmq_close().
•Positive values specify an upper bound for the
linger period in milliseconds. Pending messages shall not be discarded after a
call to
zmq_close(); attempting to terminate the socket’s
context with
zmq_term() 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.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
-1 (infinite) |
| Applicable socket types |
all |
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.
Note
The reconnection interval may be randomized by 0MQ to prevent reconnection
storms in topologies with a large number of peers per socket.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
100 |
| Applicable socket types |
all, only for connection-oriented transports |
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.
Note
Values less than ZMQ_RECONNECT_IVL will be ignored.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
0 (only use ZMQ_RECONNECT_IVL) |
| Applicable socket types |
all, only for connection-oriented transports |
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.
| Option value type |
int |
| Option value unit |
connections |
| Default value |
100 |
| Applicable socket types |
all, only for connection-oriented transports. |
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.
| Option value type |
int64_t |
| Option value unit |
bytes |
| Default value |
-1 |
| Applicable socket types |
all |
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.
| Option value type |
int |
| Option value unit |
network hops |
| Default value |
1 |
| Applicable socket types |
all, when using multicast transports |
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.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
-1 (infinite) |
| Applicable socket types |
all |
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.
| Option value type |
int |
| Option value unit |
milliseconds |
| Default value |
-1 (infinite) |
| Applicable socket types |
all |
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.
| Option value type |
int |
| Option value unit |
boolean |
| Default value |
0 (false) |
| Applicable socket types |
all, when using TCP 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.
| Option value type |
int |
| Option value unit |
boolean |
| Default value |
1 (true) |
| Applicable socket types |
all, when using TCP transports. |
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.
| Option value type |
int |
| Option value unit |
boolean |
| Default value |
0 (false) |
| Applicable socket types |
all, only for connection-oriented transports. |
ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets¶
Sets the ROUTER socket behavior when an unroutable message is encountered. A
value of 0 is the default and discards the message silently when it cannot be
routed. A value of 1 returns an
EHOSTUNREACH error code if the message
cannot be routed.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_ROUTER |
ZMQ_ROUTER_RAW: switch ROUTER socket to raw mode¶
Sets the raw mode on the ROUTER, when set to 1. When the ROUTER socket is in 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.
When using raw mode, you cannot set explicit identities, and the ZMQ_MSGMORE
flag is ignored when sending data messages. In raw mode you can close a
specific connection by sending it a zero-length message (following the
identity frame).
Note
This option is deprecated, please use ZMQ_STREAM sockets instead.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_ROUTER |
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.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_ROUTER, ZMQ_DEALER, ZMQ_REQ |
ZMQ_XPUB_VERBOSE: provide all subscription messages on XPUB sockets¶
Sets the
XPUB socket behavior on new subscriptions and unsubscriptions. A
value of
0 is the default and passes only new subscription messages to
upstream. A value of
1 passes all subscription messages upstream.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_XPUB |
ZMQ_REQ_CORRELATE: match replies with requests¶
The default behavior of REQ sockets is to rely on the ordering of messages to
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.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_REQ |
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. When
set to 1, sending another message is allowed and has the effect of
disconnecting the underlying connection to the peer from which the reply was
expected, triggering a reconnection attempt on transports that support it. The
request-reply state machine is reset and a new request is sent to the next
available peer.
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.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
ZMQ_REQ |
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.
| 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. |
ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT (or TCP_KEEPALIVE on some OS)¶
Override
TCP_KEEPCNT(or
TCP_KEEPALIVE on some OS) socket option
(where supported by OS). The default value of -1 means to skip any overrides
and leave it to OS default.
| Option value type |
int |
| Option value unit |
-1,>0 |
| Default value |
-1 (leave to OS default) |
| Applicable socket types |
all, when using TCP transports. |
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.
| Option value type |
int |
| Option value unit |
-1,>0 |
| Default value |
-1 (leave to OS default) |
| Applicable socket types |
all, when using TCP transports. |
ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option¶
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.
| Option value type |
int |
| Option value unit |
-1,>0 |
| Default value |
-1 (leave to OS default) |
| Applicable socket types |
all, when using TCP transports. |
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.
| 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_PLAIN_SERVER: Set PLAIN server role¶
Defines whether the socket will act as server for PLAIN security, see
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.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
all, when using TCP transport |
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
zmq_plain(7). If you set this to a null value, the security
mechanism used for connections shall be NULL, see
zmq_null(3).
| Option value type |
character string |
| Option value unit |
N/A |
| Default value |
not set |
| Applicable socket types |
all, when using TCP transport |
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
zmq_plain(7). If you set this to a null value, the security
mechanism used for connections shall be NULL, see
zmq_null(3).
| Option value type |
character string |
| Option value unit |
N/A |
| Default value |
not set |
| 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
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.
| Option value type |
int |
| Option value unit |
0, 1 |
| Default value |
0 |
| Applicable socket types |
all, when using TCP transport |
ZMQ_CURVE_PUBLICKEY: Set CURVE public key¶
Sets the socket’s long term public key. You must set this on CURVE client
sockets, see
zmq_curve(7). You can provide the key as 32 binary bytes,
or as a 40-character string encoded in the Z85 encoding format. The public key
must always be used with the matching secret key. To generate a public/secret
key pair, use
zmq_curve_keypair(3).
| Option value type |
binary data or Z85 text string |
| Option value size |
32 or 40 |
| 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
zmq_curve(7). You can provide the key as
32 binary bytes, or as a 40-character string encoded in the Z85 encoding
format. To generate a public/secret key pair, use
zmq_curve_keypair(3).
| Option value type |
binary data or Z85 text string |
| Option value size |
32 or 40 |
| Default value |
NULL |
| 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
zmq_curve(7). You can provide the key as 32 binary bytes,
or as a 40-character string encoded in the Z85 encoding format. This key must
have been generated together with the server’s secret key.
| Option value type |
binary data or Z85 text string |
| Option value size |
32 or 40 |
| Default value |
NULL |
| Applicable socket types |
all, when using TCP transport |
ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain¶
Sets the domain for ZAP (ZMQ RFC 27) authentication. For NULL security (the
default on all
tcp:// connections), ZAP authentication only happens if you set
a non-empty domain. For PLAIN and CURVE security, ZAP requests are always
made, if there is a ZAP handler present. See
http://rfc.zeromq.org/spec:27 for more details.
| Option value type |
character string |
| Option value unit |
N/A |
| Default value |
not set |
| Applicable socket types |
all, when using TCP transport |
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 to be sent. Ignores
ZMQ_RECVHWM and
ZMQ_SENDHWM options. Does not supports
multi-part messages, in particular, only one part of it is kept in the socket
internal queue.
| 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 |
RETURN VALUE¶
The
zmq_setsockopt() function shall return zero if successful. Otherwise
it shall return -1 and set
errno to one of the values defined below.
ERRORS¶
EINVAL
The requested option option_name is unknown, or
the requested option_len or option_value is invalid.
ETERM
The 0MQ context associated with the specified
socket was terminated.
ENOTSOCK
The provided socket was invalid.
EINTR
The operation was interrupted by delivery of a
signal.
EXAMPLE¶
Subscribing to messages on a ZMQ_SUB socket.
/* Subscribe to all messages */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
assert (rc == 0);
/* Subscribe to messages prefixed with "ANIMALS.CATS" */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);
Setting I/O thread affinity.
int64_t affinity;
/* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
affinity = 1;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
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 */
affinity = 2;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5556");
assert (rc);
SEE ALSO¶
zmq_getsockopt(3) zmq_socket(3) zmq_plain(7)
zmq_curve(7) zmq(7)
AUTHORS¶
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.
