zmq_setsockopt(3)

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 ØMQ 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 ØMQ 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, ØMQ 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

ØMQ 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 ØMQ shall queue in memory for any single peer +that the specified socket is communicating with. A value of zero means no +limit.

+ + + + + + + + + + + + + + + + +

+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 ØMQ 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 +ØMQ 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 ØMQ +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 ØMQ 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 ØMQ 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 ØMQ framing. This lets ØMQ applications talk to non-ØMQ 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 ØMQ 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);

AUTHORS

This page was written by the ØMQ community. To make a change please +read the ØMQ Contribution Policy at http://www.zeromq.org/docs:contributing.

+zmq_setsockopt(3) Manual Page +

NAME

SYNOPSIS

DESCRIPTION

ZMQ_SNDHWM: Set high water mark for outbound messages

ZMQ_RCVHWM: Set high water mark for inbound messages

ZMQ_AFFINITY: Set I/O thread affinity

ZMQ_SUBSCRIBE: Establish message filter

ZMQ_UNSUBSCRIBE: Remove message filter

ZMQ_IDENTITY: Set socket identity

ZMQ_RATE: Set multicast data rate

ZMQ_RECOVERY_IVL: Set multicast recovery interval

ZMQ_SNDBUF: Set kernel transmit buffer size

ZMQ_RCVBUF: Set kernel receive buffer size

ZMQ_LINGER: Set linger period for socket shutdown

ZMQ_RECONNECT_IVL: Set reconnection interval

ZMQ_RECONNECT_IVL_MAX: Set maximum reconnection interval

ZMQ_BACKLOG: Set maximum length of the queue of outstanding connections

ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size

ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets

ZMQ_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN

ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN

ZMQ_IPV6: Enable IPv6 on socket

ZMQ_IPV4ONLY: Use IPv4-only on socket

ZMQ_IMMEDIATE: Queue messages only to completed connections

ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets

ZMQ_ROUTER_RAW: switch ROUTER socket to raw mode

ZMQ_PROBE_ROUTER: bootstrap connections to ROUTER sockets

ZMQ_XPUB_VERBOSE: provide all subscription messages on XPUB sockets

ZMQ_REQ_CORRELATE: match replies with requests

ZMQ_REQ_RELAXED: relax strict alternation between request and reply

ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option

ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT (or TCP_KEEPALIVE on some OS)

ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option

ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option

ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections

ZMQ_PLAIN_SERVER: Set PLAIN server role

ZMQ_PLAIN_USERNAME: Set PLAIN security username

ZMQ_PLAIN_PASSWORD: Set PLAIN security password

ZMQ_CURVE_SERVER: Set CURVE server role

ZMQ_CURVE_PUBLICKEY: Set CURVE public key

ZMQ_CURVE_SECRETKEY: Set CURVE secret key

ZMQ_CURVE_SERVERKEY: Set CURVE server key

ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain

ZMQ_CONFLATE: Keep only last message

RETURN VALUE

ERRORS

EXAMPLE

SEE ALSO

AUTHORS