ZMQ_SETSOCKOPT(3) 0MQ Manual ZMQ_SETSOCKOPT(3)NAMEzmq_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.
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.
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 ALSOzmq_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
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0MQ 4.0.4 03/10/2014 ZMQ_SETSOCKOPT(3)
