ZMQ_SETSOCKOPT(3) 0MQ Manual ZMQ_SETSOCKOPT(3)
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_HANDOVER, ZMQ_ROUTER_MANDATORY,
ZMQ_PROBE_ROUTER, ZMQ_XPUB_VERBOSE, ZMQ_XPUB_VERBOSER,
ZMQ_REQ_CORRELATE, ZMQ_REQ_RELAXED, ZMQ_SNDHWM and ZMQ_RCVHWM, 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. 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).
The following socket options can be set with the zmq_setsockopt()
function:
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_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_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.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP or UDP
transports.
ZMQ_CONNECT_RID: Assign the next outbound connection id
This option name is now deprecated. Use ZMQ_CONNECT_ROUTING_ID instead.
ZMQ_CONNECT_RID remains as an alias for now.
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.
Useful when connecting ROUTER to ROUTER, or STREAM to STREAM, as it
allows for immediate sending to peers. Outbound routing id framing
requirements for ROUTER and STREAM sockets apply.
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).
Option value type binary data
Option value unit N/A
Default value NULL
Applicable socket types ZMQ_ROUTER, ZMQ_STREAM
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_RCVHWM and ZMQ_SNDHWM options. Does not support
multi-part messages, in particular, only one part of it is kept in the
socket internal queue.
Note
If recv is not called on the inbound socket, the queue and memory
will grow with each message received. Use zmq_getsockopt(3) with
ZMQ_EVENTS to trigger the conflation of the messages.
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
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.
Option value type int
Option value unit milliseconds
Default value 0 (disabled)
Applicable socket types all, when using TCP
transports.
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
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
zmq_curve_keypair(3). To derive the public key from a secret key, use
zmq_curve_public(3).
Note
an option value size of 40 is supported for backwards
compatibility, though is deprecated.
Option value type binary data or Z85 text
string
Option value size 32 or 41
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 and terminated in a null byte. To generate a
public/secret key pair, use zmq_curve_keypair(3). To derive the public
key from a secret key, use zmq_curve_public(3).
Note
an option value size of 40 is supported for backwards
compatibility, though is deprecated.
Option value type binary data or Z85 text
string
Option value size 32 or 41
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
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_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
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 zmq_curve_keypair(3).
Note
an option value size of 40 is supported for backwards
compatibility, though is deprecated.
Option value type binary data or Z85 text
string
Option value size 32 or 41
Default value NULL
Applicable socket types all, when using TCP
transport
ZMQ_DISCONNECT_MSG: set a disconnect message that the socket will generate
when accepted peer disconnect
When set, the socket will generate a disconnect message when accepted
peer has been disconnected. You may set this on ROUTER, SERVER and PEER
sockets. The combination with ZMQ_HEARTBEAT_IVL is powerful and
simplify protocols, when heartbeat recognize a connection drop it will
generate a disconnect message that can match the protocol of the
application.
Option value type binary data
Option value unit N/A
Default value NULL
Applicable socket types ZMQ_ROUTER, ZMQ_SERVER and
ZMQ_PEER
ZMQ_GSSAPI_PLAINTEXT: Disable GSSAPI encryption
Defines whether communications on the socket will be encrypted, see
zmq_gssapi(7). A value of 1 means that communications will be
plaintext. A value of 0 means communications will be encrypted.
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
Sets the name of the principal for whom GSSAPI credentials should be
acquired.
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
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.
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
Sets the name of the principal of the GSSAPI server to which a GSSAPI
client intends to connect.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP
transport
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).
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).
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_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 information (socket type, routing id, security) that
occurs when a connection 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.
Option value type int
Option value unit milliseconds
Default value 30000
Applicable socket types all but ZMQ_STREAM, only
for connection-oriented
transports
ZMQ_HELLO_MSG: set an hello message that will be sent when a new peer
connect
When set, the socket will automatically send an hello message when a
new connection is made or accepted. You may set this on DEALER, ROUTER,
CLIENT, SERVER and PEER sockets. The combination with ZMQ_HEARTBEAT_IVL
is powerful and simplify protocols, as now heartbeat and sending the
hello message can be left out of protocols and be handled by zeromq.
Option value type binary data
Option value unit N/A
Default value NULL
Applicable socket types ZMQ_ROUTER, ZMQ_DEALER,
ZMQ_CLIENT, ZMQ_SERVER and
ZMQ_PEER
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.
Option value type int
Option value unit milliseconds
Default value 0
Applicable socket types all, when using
connection-oriented
transports
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.
Option value type int
Option value unit milliseconds
Default value 0 normally,
ZMQ_HEARTBEAT_IVL if it is
set
Applicable socket types all, when using
connection-oriented
transports
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 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.
Option value type int
Option value unit milliseconds
Default value 0
Maximum value 6553599 (which is 2^16-1
deciseconds)
Applicable socket types all, when using
connection-oriented
transports
ZMQ_IDENTITY: Set socket identity
This option name is now deprecated. Use ZMQ_ROUTING_ID instead.
ZMQ_IDENTITY remains as an alias for now.
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_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.
Option value type int
Option value unit 0,1
Default value 0
Applicable socket types ZMQ_PUB, ZMQ_XPUB, ZMQ_SUB
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_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
disconnected with zmq_disconnect(3) or closed with zmq_close(3), and
further affects the termination of the socket’s context with
zmq_ctx_term(3). The following outlines the different behaviours:
• A value of -1 specifies an infinite linger period. Pending messages
shall not be discarded after a call to zmq_disconnect() or
zmq_close(); attempting to terminate the socket’s context with
zmq_ctx_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 after a call to zmq_disconnect() or
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_disconnect() or zmq_close(); attempting to terminate the
socket’s context with zmq_ctx_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_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_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
(zmq_z85_encode(3)).
Note
in DRAFT state, not yet available in stable releases.
Option value type character string
Option value unit N/A
Default value not set
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_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.
Option value type int
Option value unit bytes
Default value 1500
Applicable socket types all, when using multicast
transports
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_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_USE_FD: Set the pre-allocated socket file descriptor
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.
Option value type int
Option value unit file descriptor
Default value -1
Applicable socket types all bound sockets, when
using IPC or TCP transport
ZMQ_PRIORITY: Set the Priority on socket
Sets the protocol-defined priority for all packets to be sent on this
socket, where supported by the OS. In Linux, values greater than 6
require admin capability (CAP_NET_ADMIN)
Option value type int
Option value unit >0
Default value 0
Applicable socket types all, only for
connection-oriented
transports
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_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_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 -1 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 -1
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.
Note
0MQ does not guarantee that the socket will be able to queue as
many as ZMQ_RCVHWM messages, and the actual limit may be lower or
higher, depending on socket transport. A notable example is for
sockets using TCP transport; see zmq_tcp(7).
Option value type int
Option value unit messages
Default value 1000
Applicable socket types all
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_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_RECONNECT_STOP: Set condition where reconnection will stop
The ZMQ_RECONNECT_STOP option shall set the conditions under which
automatic reconnection will stop. This can be useful when a process
binds to a wild-card port, where the OS supplies an ephemeral port.
The ZMQ_RECONNECT_STOP_CONN_REFUSED option will stop reconnection when
0MQ receives the ECONNREFUSED return code from the connect. This
indicates that there is no code bound to the specified endpoint.
The ZMQ_RECONNECT_STOP_HANDSHAKE_FAILED option will stop reconnection
if the 0MQ handshake fails. This can be used to detect and/or prevent
errant connection attempts to non-0MQ sockets. Note that when
specifying this option you may also want to set ZMQ_HANDSHAKE_IVL — the
default handshake interval is 30000 (30 seconds), which is typically
too large.
The ZMQ_RECONNECT_STOP_AFTER_DISCONNECT option will stop reconnection
when zmq_disconnect() has been called. This can be useful when the
user’s request failed (server not ready), as the socket does not need
to continue to reconnect after user disconnect actively.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit 0,
ZMQ_RECONNECT_STOP_CONN_REFUSED,
ZMQ_RECONNECT_STOP_HANDSHAKE_FAILED,
ZMQ_RECONNECT_STOP_CONN_REFUSED
|
ZMQ_RECONNECT_STOP_HANDSHAKE_FAILED
Default value 0
Applicable socket types all, only for connection-oriented
transports (ZMQ_HANDSHAKE_IVL is not
applicable for ZMQ_STREAM sockets)
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_REQ_CORRELATE: match replies with requests
The default behaviour 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 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.
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_ROUTER_HANDOVER: handle duplicate client routing ids on ROUTER sockets
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.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_ROUTER
ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets
Sets the ROUTER socket behaviour when an unroutable message is
encountered. A value of 0 is the default and discards the message
silently when it cannot be 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.
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 event on every call to zmq_poll resp. zmq_poller_wait_all.
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_SNDMORE 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 routing id 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_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.
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_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 -1 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 -1
Applicable socket types all
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 90%
lower depending on the flow of messages on the socket. The socket
may even be able to accept more messages than the ZMQ_SNDHWM
threshold; a notable example is for sockets using TCP transport;
see zmq_tcp(7).
Option value type int
Option value unit messages
Default value 1000
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_SOCKS_PROXY: Set SOCKS5 proxy address
Sets the SOCKS5 proxy address that shall be used by the socket for the
TCP connection(s). Supported authentication methods are: no
authentication or basic authentication when setup with
ZMQ_SOCKS_USERNAME. 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).
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP
transport
ZMQ_SOCKS_USERNAME: Set SOCKS username and select basic authentication
Sets the username for authenticated connection to the SOCKS5 proxy. If
you set this to a non-null and non-empty value, the authentication
method used for the SOCKS5 connection shall be basic authentication. In
this case, use ZMQ_SOCKS_PASSWORD option in order to set the password.
If you set this to a null value or empty value, the authentication
method shall be no authentication, the default.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP
transport
ZMQ_SOCKS_PASSWORD: Set SOCKS basic authentication password
Sets the password for authenticating to the SOCKS5 proxy server. This
is used only when the SOCKS5 authentication method has been set to
basic authentication through the ZMQ_SOCKS_USERNAME option. Setting
this to a null value (the default) is equivalent to an empty password
string.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP
transport
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.
Option value type int
Option value unit 0, 1
Default value 1
Applicable socket types ZMQ_STREAM
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_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_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_IDLE: Override TCP_KEEPIDLE (or TCP_KEEPALIVE on some OS)
Override TCP_KEEPIDLE (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_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_MAXRT: Set TCP Maximum Retransmit Timeout
On OSes where it is supported, sets how long before an unacknowledged
TCP 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.
Option value type int
Option value unit milliseconds
Default value 0 (leave to OS default)
Applicable socket types all, when using TCP
transports.
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 on intermediate network equipment that inspect the
ToS field and provide a path for low-delay, high-throughput,
highly-reliable service, etc.
Option value type int
Option value unit >0
Default value 0
Applicable socket types all, only for
connection-oriented
transports
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_XPUB_VERBOSE: pass duplicate subscribe messages on XPUB socket
Sets the XPUB socket behaviour on new duplicated subscriptions. If
enabled, the socket passes all subscribe messages to the caller. If
disabled, only the first subscription to each filter will be passed.
The default is 0 (disabled).
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_XPUB
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 (disabled).
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_XPUB
ZMQ_XPUB_MANUAL: change the subscription handling to manual
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.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_XPUB
ZMQ_XPUB_MANUAL_LAST_VALUE: change the subscription handling to manual
This option is similar to ZMQ_XPUB_MANUAL. The difference is that
ZMQ_XPUB_MANUAL_LAST_VALUE changes the XPUB socket behaviour to send
the first message to the last subscriber after the socket receives a
subscription and call setsockopt with ZMQ_SUBSCRIBE on XPUB socket.
This prevents duplicated messages when using last value caching(LVC).
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_XPUB
ZMQ_XPUB_NODROP: do not silently drop messages if SENDHWM is reached
Sets the XPUB socket behaviour to return error EAGAIN if SENDHWM is
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.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types ZMQ_XPUB, ZMQ_PUB
ZMQ_XPUB_WELCOME_MSG: set welcome message that will be received by
subscriber when connecting
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 length of zero to disable welcome message.
Option value type binary data
Option value unit N/A
Default value NULL
Applicable socket types ZMQ_XPUB
ZMQ_ONLY_FIRST_SUBSCRIBE: Process only first subscribe/unsubscribe in a
multipart message
If set, only the first part of the multipart message is processed as a
subscribe/unsubscribe message. The rest are forwarded as user data
regardless of message contents.
It not set (default), subscribe/unsubscribe messages in a multipart
message are processed as such regardless of their number and order.
Option value type int
Option value unit boolean
Default value 0 (false)
Applicable socket types ZMQ_XSUB, ZMQ_XPUB
ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain
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 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. See
http://rfc.zeromq.org/spec:27 for more details.
Option value type character string
Option value unit N/A
Default value empty
Applicable socket types all, when using TCP
transport
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.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types all, when using ZAP
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 allowing / blocking.
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 allowing / blocking.
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 allowing / blocking.
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 allowing / blocking.
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.
Option value type int
Option value unit boolean
Default value 1 (true)
Applicable socket types all, when using TCP
transports.
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.
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.
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.
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.
Option value type int
Option value unit milliseconds
Default value -1
Applicable socket types all, when using VMCI
transport
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.
Option value type int
Option value unit 0, 1
Default value 1
Applicable socket types ZMQ_RADIO, when using UDP
multicast transport
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.
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
ZMQ_IN_BATCH_SIZE: Maximal receive batch size
Sets the maximal amount of messages that can be received in a single
recv system call. WARNING: this option should almost never be changed.
The default has been chosen to offer the best compromise between
latency and throughtput. In the vast majority of cases, changing this
option will result in worst result if not outright breakages.
Cannot be zero.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit messages
Default value 8192
Applicable socket types All, when using TCP, IPC,
PGM or NORM transport.
ZMQ_OUT_BATCH_SIZE: Maximal send batch size
Sets the maximal amount of messages that can be sent in a single send
system call. WARNING: this option should almost never be changed. The
default has been chosen to offer the best compromise between latency
and throughtput. In the vast majority of cases, changing this option
will result in worst result if not outright breakages.
Cannot be zero.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit messages
Default value 8192
Applicable socket types All, when using TCP, IPC,
PGM or NORM transport.
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.
0MQ 4.3.4 01/18/2023 ZMQ_SETSOCKOPT(3)
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