Optional options: {Optional affinity?: numberZMQ_AFFINITY
I/O thread affinity, which determines which threads from the ØMQ I/O thread pool associated with the socket's context shall handle newly created connections.
Note: This value is a bit mask, but values higher than Number.MAX_SAFE_INTEGER may not be represented accurately! This currently means that configurations beyond 52 threads are unreliable.
Optional backlog?: numberZMQ_BACKLOG
Maximum length of the queue of outstanding peer connections for the specified socket. This only applies to connection-oriented transports.
Optional connectZMQ_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.
Optional context?: ContextOptional curveZMQ_CURVE_PUBLICKEY
Sets the socket's long term public key. You must set this on CURVE client sockets. A server socket does not need to know its own public key. You can create a new keypair with curveKeyPair().
Optional curveZMQ_CURVE_SECRETKEY
Sets the socket's long term secret key. You must set this on both CURVE client and server sockets. You can create a new keypair with curveKeyPair().
Optional curveZMQ_CURVE_SERVER
Defines whether the socket will act as server for CURVE security. A value of true means the socket will act as CURVE server. A value of false means the socket will not act as CURVE server, and its security role then depends on other option settings.
Optional curveZMQ_CURVE_SERVERKEY
Sets the socket's long term server key. This is the public key of the CURVE server socket. You must set this on CURVE client sockets. This key must have been generated together with the server's secret key. You can create a new keypair with curveKeyPair().
Optional gssapiOptional gssapiOptional gssapiOptional gssapiOptional gssapiOptional gssapiOptional handshakeZMQ_HANDSHAKE_IVL
Handshaking is the exchange of socket configuration information (socket type, identity, 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.
Optional heartbeatZMQ_HEARTBEAT_IVL
Interval in milliseconds between sending ZMTP heartbeats for the specified socket. If this option is greater than 0, then a PING ZMTP command will be sent after every interval.
Optional heartbeatZMQ_HEARTBEAT_TTL
The timeout in milliseconds 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 heartbeatInterval is 0. Internally, this value is rounded down to the nearest decisecond, any value less than 100 will have no effect.
Optional heartbeatZMQ_HEARTBEAT_TIMEOUT
How long (in milliseconds) to wait before timing-out a connection after sending a PING ZMTP command and not receiving any traffic. This option is only valid if heartbeatInterval is greater than 0. The connection will time out if there is no traffic received after sending the PING command. The received traffic does not have to be a PONG command - any received traffic will cancel the timeout.
Optional immediate?: booleanZMQ_IMMEDIATE
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 (Request, Push, Dealer). If this option is set to true, 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.
Optional interface?: null | stringZMQ_BINDTODEVICE
Binds the socket to the given network interface (Linux only). Allows to use Linux VRF, see: https://www.kernel.org/doc/Documentation/networking/vrf.txt. Requires the program to be ran as root or with CAP_NET_RAW.
Optional ipv6?: booleanZMQ_IPV6
Enable or disable IPv6. When IPv6 is enabled, the socket will connect to, or accept connections from, both IPv4 and IPv6 hosts.
Optional linger?: numberZMQ_LINGER
Determines how long pending messages which have yet to be sent to a peer shall linger in memory after a socket is closed with close().
Optional loopbackZMQ_LOOPBACK_FASTPATH
Enable faster TCP connections on loopback devices. An application can enable this option to reduce the latency and improve the performance of loopback operations on a TCP socket on Windows.
Optional maxZMQ_MAXMSGSIZE
Limits the size of the inbound message. If a peer sends a message larger than the limit it is disconnected. Value of -1 means no limit.
Optional multicastZMQ_MULTICAST_HOPS
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.
Optional multicastZMQ_MULTICAST_MAXTPDU
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.
Optional plainZMQ_PLAIN_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.
Optional plainZMQ_PLAIN_SERVER
Defines whether the socket will act as server for PLAIN security. A value of true means the socket will act as PLAIN server. A value of false means the socket will not act as PLAIN server, and its security role then depends on other option settings.
Optional plainZMQ_PLAIN_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.
Optional rate?: numberZMQ_RATE
Maximum send or receive data rate for multicast transports such as pgm.
Optional receiveZMQ_RCVBUF
Underlying kernel receive buffer size in bytes. A value of -1 means leave the OS default unchanged.
Optional receiveZMQ_RCVHWM
The high water mark is a hard limit on the maximum number of incoming 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.
Optional receiveZMQ_RCVTIMEO
Sets the timeout receiving messages on the socket. If the value is 0, receive() will return a rejected promise immediately if there is no message to receive. If the value is -1, it will wait asynchronously until a message is available. For all other values, it will wait for a message for that amount of time before rejecting.
Optional reconnectZMQ_RECONNECT_IVL
Period ØMQ shall wait between attempts to reconnect disconnected peers when using connection-oriented transports. The value -1 means no reconnection.
Optional reconnectZMQ_RECONNECT_IVL_MAX
Maximum period ØMQ shall wait between attempts to reconnect. On each reconnect attempt, the previous interval shall be doubled until reconnectMaxInterval is reached. This allows for exponential backoff strategy. Zero (the default) means no exponential backoff is performed and reconnect interval calculations are only based on reconnectInterval.
Optional recoveryZMQ_RECOVERY_IVL
Maximum time in milliseconds that a receiver can be absent from a multicast group before unrecoverable data loss will occur.
Optional routingZMQ_ROUTING_ID
The identity of the specified socket when connecting to a Router socket.
Optional sendZMQ_SNDBUF
Underlying kernel transmit buffer size in bytes. A value of -1 means leave the OS default unchanged.
Optional sendZMQ_SNDHWM
The high water mark is a hard limit on the maximum number of outgoing 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.
Optional sendZMQ_SNDTIMEO
Sets the timeout for sending messages on the socket. If the value is 0, send() will return a rejected promise immediately if the message cannot be sent. If the value is -1, it will wait asynchronously until the message is sent. For all other values, it will try to send the message for that amount of time before rejecting.
Optional socksZMQ_SOCKS_PROXY
The SOCKS5 proxy address that shall be used by the socket for the TCP connection(s). Does not support SOCKS5 authentication. If the endpoints are domain names instead of addresses they shall not be resolved and they shall be forwarded unchanged to the SOCKS proxy service in the client connection request message (address type 0x03 domain name).
Optional tcpZMQ_TCP_ACCEPT_FILTER
Assign a filter 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 set to null. Filter is a string with IPv6 or IPv4 CIDR.
Optional tcpZMQ_TCP_KEEPALIVE
Override SO_KEEPALIVE socket option (if supported by OS). The default value of -1 leaves it to the OS default.
Optional tcpZMQ_TCP_KEEPALIVE_CNT
Overrides TCP_KEEPCNT socket option (if supported by OS). The default value of -1 leaves it to the OS default.
Optional tcpZMQ_TCP_KEEPALIVE_IDLE
Overrides TCP_KEEPIDLE / TCP_KEEPALIVE socket option (if supported by OS). The default value of -1 leaves it to the OS default.
Optional tcpZMQ_TCP_KEEPALIVE_INTVL
Overrides TCP_KEEPINTVL socket option (if supported by the OS). The default value of -1 leaves it to the OS default.
Optional tcpZMQ_TCP_MAXRT
Sets how long before an unacknowledged TCP retransmit times out (if supported by the OS). 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.
Optional typeZMQ_TOS
Sets the ToS fields (the Differentiated Services (DS) and Explicit Congestion Notification (ECN) field) of the IP header. The ToS field is typically used to specify a packet's 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.
Optional vmciZMQ_VMCI_BUFFER_MAX_SIZE
Maximum size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
Optional vmciZMQ_VMCI_BUFFER_MIN_SIZE
Minimum size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
Optional vmciZMQ_VMCI_BUFFER_SIZE
The size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
Optional vmciZMQ_VMCI_CONNECT_TIMEOUT
Connection timeout for the socket. For vmci:// transports only.
Optional zapZMQ_ZAP_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.
Optional zapZMQ_ZAP_ENFORCE_DOMAIN
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.
ZMQ_AFFINITY
I/O thread affinity, which determines which threads from the ØMQ I/O thread pool associated with the socket's context shall handle newly created connections.
Note: This value is a bit mask, but values higher than Number.MAX_SAFE_INTEGER may not be represented accurately! This currently means that configurations beyond 52 threads are unreliable.
ZMQ_BACKLOG
Maximum length of the queue of outstanding peer connections for the specified socket. This only applies to connection-oriented transports.
Readonly closedWhether this socket was previously closed with close().
ZMQ_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.
Readonly contextContext that this socket belongs to.
ZMQ_CURVE_PUBLICKEY
Sets the socket's long term public key. You must set this on CURVE client sockets. A server socket does not need to know its own public key. You can create a new keypair with curveKeyPair().
ZMQ_CURVE_SECRETKEY
Sets the socket's long term secret key. You must set this on both CURVE client and server sockets. You can create a new keypair with curveKeyPair().
ZMQ_CURVE_SERVER
Defines whether the socket will act as server for CURVE security. A value of true means the socket will act as CURVE server. A value of false means the socket will not act as CURVE server, and its security role then depends on other option settings.
ZMQ_CURVE_SERVERKEY
Sets the socket's long term server key. This is the public key of the CURVE server socket. You must set this on CURVE client sockets. This key must have been generated together with the server's secret key. You can create a new keypair with curveKeyPair().
Readonly eventsEvent Observer for this socket. This starts up a ØMQ monitoring socket internally that receives all socket events.
ZMQ_HANDSHAKE_IVL
Handshaking is the exchange of socket configuration information (socket type, identity, 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.
ZMQ_HEARTBEAT_IVL
Interval in milliseconds between sending ZMTP heartbeats for the specified socket. If this option is greater than 0, then a PING ZMTP command will be sent after every interval.
ZMQ_HEARTBEAT_TTL
The timeout in milliseconds 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 heartbeatInterval is 0. Internally, this value is rounded down to the nearest decisecond, any value less than 100 will have no effect.
ZMQ_HEARTBEAT_TIMEOUT
How long (in milliseconds) to wait before timing-out a connection after sending a PING ZMTP command and not receiving any traffic. This option is only valid if heartbeatInterval is greater than 0. The connection will time out if there is no traffic received after sending the PING command. The received traffic does not have to be a PONG command - any received traffic will cancel the timeout.
ZMQ_IMMEDIATE
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 (Request, Push, Dealer). If this option is set to true, 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.
ZMQ_BINDTODEVICE
Binds the socket to the given network interface (Linux only). Allows to use Linux VRF, see: https://www.kernel.org/doc/Documentation/networking/vrf.txt. Requires the program to be ran as root or with CAP_NET_RAW.
ZMQ_IPV6
Enable or disable IPv6. When IPv6 is enabled, the socket will connect to, or accept connections from, both IPv4 and IPv6 hosts.
Readonly lastZMQ_LAST_ENDPOINT
The last endpoint bound for TCP and IPC transports.
ZMQ_LINGER
Determines how long pending messages which have yet to be sent to a peer shall linger in memory after a socket is closed with close().
ZMQ_LOOPBACK_FASTPATH
Enable faster TCP connections on loopback devices. An application can enable this option to reduce the latency and improve the performance of loopback operations on a TCP socket on Windows.
ZMQ_MAXMSGSIZE
Limits the size of the inbound message. If a peer sends a message larger than the limit it is disconnected. Value of -1 means no limit.
ZMQ_MULTICAST_HOPS
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.
ZMQ_MULTICAST_MAXTPDU
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.
ZMQ_PLAIN_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.
ZMQ_PLAIN_SERVER
Defines whether the socket will act as server for PLAIN security. A value of true means the socket will act as PLAIN server. A value of false means the socket will not act as PLAIN server, and its security role then depends on other option settings.
ZMQ_PLAIN_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.
ZMQ_RATE
Maximum send or receive data rate for multicast transports such as pgm.
Readonly readableWhether any messages are currently available. If true, the next call to receive() will immediately read a message from the socket. For sockets that cannot receive messsages this is always false.
ZMQ_RCVBUF
Underlying kernel receive buffer size in bytes. A value of -1 means leave the OS default unchanged.
ZMQ_RCVHWM
The high water mark is a hard limit on the maximum number of incoming 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.
ZMQ_RCVTIMEO
Sets the timeout receiving messages on the socket. If the value is 0, receive() will return a rejected promise immediately if there is no message to receive. If the value is -1, it will wait asynchronously until a message is available. For all other values, it will wait for a message for that amount of time before rejecting.
ZMQ_RECONNECT_IVL
Period ØMQ shall wait between attempts to reconnect disconnected peers when using connection-oriented transports. The value -1 means no reconnection.
ZMQ_RECONNECT_IVL_MAX
Maximum period ØMQ shall wait between attempts to reconnect. On each reconnect attempt, the previous interval shall be doubled until reconnectMaxInterval is reached. This allows for exponential backoff strategy. Zero (the default) means no exponential backoff is performed and reconnect interval calculations are only based on reconnectInterval.
ZMQ_RECOVERY_IVL
Maximum time in milliseconds that a receiver can be absent from a multicast group before unrecoverable data loss will occur.
ZMQ_ROUTING_ID
The identity of the specified socket when connecting to a Router socket.
Readonly securityZMQ_MECHANISM
Returns the current security mechanism for the socket, if any. The security mechanism is set implictly by using any of the relevant security options. The returned value is one of:
null - No security mechanism is used."plain" - The PLAIN mechanism defines a simple username/password mechanism that lets a server authenticate a client. PLAIN makes no attempt at security or confidentiality."curve" - The CURVE mechanism defines a mechanism for secure authentication and confidentiality for communications between a client and a server. CURVE is intended for use on public networks."gssapi" - The GSSAPI mechanism defines a mechanism for secure authentication and confidentiality for communications between a client and a server using the Generic Security Service Application Program Interface (GSSAPI). The GSSAPI mechanism can be used on both public and private networks.ZMQ_SNDBUF
Underlying kernel transmit buffer size in bytes. A value of -1 means leave the OS default unchanged.
ZMQ_SNDHWM
The high water mark is a hard limit on the maximum number of outgoing 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.
ZMQ_SNDTIMEO
Sets the timeout for sending messages on the socket. If the value is 0, send() will return a rejected promise immediately if the message cannot be sent. If the value is -1, it will wait asynchronously until the message is sent. For all other values, it will try to send the message for that amount of time before rejecting.
ZMQ_SOCKS_PROXY
The SOCKS5 proxy address that shall be used by the socket for the TCP connection(s). Does not support SOCKS5 authentication. If the endpoints are domain names instead of addresses they shall not be resolved and they shall be forwarded unchanged to the SOCKS proxy service in the client connection request message (address type 0x03 domain name).
ZMQ_TCP_ACCEPT_FILTER
Assign a filter 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 set to null. Filter is a string with IPv6 or IPv4 CIDR.
ZMQ_TCP_KEEPALIVE
Override SO_KEEPALIVE socket option (if supported by OS). The default value of -1 leaves it to the OS default.
ZMQ_TCP_KEEPALIVE_CNT
Overrides TCP_KEEPCNT socket option (if supported by OS). The default value of -1 leaves it to the OS default.
ZMQ_TCP_KEEPALIVE_IDLE
Overrides TCP_KEEPIDLE / TCP_KEEPALIVE socket option (if supported by OS). The default value of -1 leaves it to the OS default.
ZMQ_TCP_KEEPALIVE_INTVL
Overrides TCP_KEEPINTVL socket option (if supported by the OS). The default value of -1 leaves it to the OS default.
ZMQ_TCP_MAXRT
Sets how long before an unacknowledged TCP retransmit times out (if supported by the OS). 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.
Readonly threadZMQ_THREAD_SAFE
Whether or not the socket is threadsafe. Currently only DRAFT sockets is thread-safe.
Readonly typeZMQ_TYPE
Retrieve the socket type. This is fairly useless because you can test the socket class with e.g. socket instanceof Dealer.
ZMQ_TOS
Sets the ToS fields (the Differentiated Services (DS) and Explicit Congestion Notification (ECN) field) of the IP header. The ToS field is typically used to specify a packet's 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.
ZMQ_VMCI_BUFFER_MAX_SIZE
Maximum size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
ZMQ_VMCI_BUFFER_MIN_SIZE
Minimum size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
ZMQ_VMCI_BUFFER_SIZE
The size of the underlying buffer for the socket. Used during negotiation before the connection is established. For vmci:// transports only.
ZMQ_VMCI_CONNECT_TIMEOUT
Connection timeout for the socket. For vmci:// transports only.
Readonly writableWhether any messages can be queued for sending. If true, the next call to send() will immediately queue a message on the socket. For sockets that cannot send messsages this is always false.
ZMQ_ZAP_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.
ZMQ_ZAP_ENFORCE_DOMAIN
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.
Asynchronously iterate over messages becoming available on the socket. When the socket is closed with close(), the iterator will return. Returning early from the iterator will not close the socket unless it also goes out of scope.
for await (const [msg] of socket) {
// handle messages
}
Binds the socket to the given address. During bind() the socket cannot be used. Do not call any other methods until the returned promise resolves. Make sure to use await.
You can use * in place of a hostname to bind on all interfaces/addresses, and you can use * in place of a port to bind to a random port (which can be retrieved with lastEndpoint later).
await socket.bind("tcp://127.0.0.1:3456")
await socket.bind("tcp://*:3456") // binds on all interfaces
await socket.bind("tcp://127.0.0.1:*") // binds on random port
Resolved when the socket was successfully bound.
Address to bind this socket to.
Closes the socket and disposes of all resources. Any messages that are queued may be discarded or sent in the background depending on the linger setting.
After this method is called, it is no longer possible to call any other methods on this socket.
Sockets that go out of scope and have no receive() or send() operations in progress will automatically be closed. Therefore it is not necessary in most applications to call close() manually.
Calling this method on a socket that is already closed is a no-op.
Disconnects a previously connected socket from the given address and returns immediately. Disonnection will happen asynchronously in the background.
socket.disconnect("tcp://127.0.0.1:3456")
The previously connected address to disconnect from.
Protected getProtected getProtected getProtected getProtected getProtected getWaits for the next single or multipart message to become availeble on the socket. Reads a message immediately if possible. If no messages can be read, it will wait asynchonously. The promise will be resolved with an array containing the parts of the next message when available.
const [msg] = await socket.receive()
const [part1, part2] = await socket.receive()
Reading may fail (eventually) if the socket has been configured with a receiveTimeout.
A call to receive() is guaranteed to return with a resolved promise immediately if a message could be read from the socket directly.
Only one asynchronously blocking call to receive() can be in progress simultaneously. If you call receive() again on the same socket it will return a rejected promise with an EBUSY error. For example, if no messages can be read and no await is used:
socket.receive() // -> pending promise until read is possible
socket.receive() // -> promise rejection with `EBUSY` error
Note: Due to the nature of Node.js and to avoid blocking the main thread, this method always attempts to read messages with the ZMQ_DONTWAIT flag. It polls asynchronously if reading is not currently possible. This means that all functionality related to timeouts and blocking behaviour is reimplemented in the Node.js bindings. Any differences in behaviour with the native ZMQ library is considered a bug.
Resolved with message parts that were successfully read.
Sends a single message or a multipart message on the socket. Queues the message immediately if possible, and returns a resolved promise. If the message cannot be queued because the high water mark has been reached, it will wait asynchronously. The promise will be resolved when the message was queued successfully.
await socket.send("hello world")
await socket.send(["hello", "world"])
Queueing may fail eventually if the socket has been configured with a sendTimeout.
A call to send() is guaranteed to return with a resolved promise immediately if the message could be queued directly.
Only one asynchronously blocking call to send() may be executed simultaneously. If you call send() again on a socket that is in the mute state it will return a rejected promise with an EBUSY error.
The reason for disallowing multiple send() calls simultaneously is that it could create an implicit queue of unsendable outgoing messages. This would circumvent the socket's sendHighWaterMark. Such an implementation could even exhaust all system memory and cause the Node.js process to abort.
For most application you should not notice this implementation detail. Only in rare occasions will a call to send() that does not resolve immediately be undesired. Here are some common scenarios:
If you wish to send a message, use await send(...). ZeroMQ socket types have been carefully designed to give you the correct blocking behaviour on the chosen socket type in almost all cases:
If sending is not possible, it is often better to wait than to continue as if nothing happened. For example, on a Request socket, you can only receive a reply once a message has been sent; so waiting until a message could be queued before continuing with the rest of the program (likely to read from the socket) is required.
Certain socket types (such as Router) will always allow queueing messages and await send(...) won't delay any code that comes after. This makes sense for routers, since typically you don't want a single send operation to stop the handling of other incoming or outgoing messages.
If you wish to send on an occasionally blocking socket (for example on a Router with the mandatory option set, or on a Dealer) and you're 100% certain that dropping a message is better than blocking, then you can set the sendTimeout option to 0 to effectively force send() to always resolve immediately. Be prepared to catch exceptions if sending a message is not immediately possible.
If you wish to send on a socket and messages should be queued before they are dropped, you should implement a simple queue in JavaScript. Such a queue is not provided by this library because most real world applications need to deal with undeliverable messages in more complex ways - for example, they might need to reply with a status message; or first retry delivery a certain number of times before giving up.
Resolved when the message was successfully queued.
Single message or multipart message to queue for sending.
Rest ...options: []Any options, if applicable to the socket type (DRAFT only).
Protected setProtected setProtected setProtected setProtected setProtected setUnbinds the socket to the given address. During unbind() the socket cannot be used. Do not call any other methods until the returned promise resolves. Make sure to use await.
Resolved when the socket was successfully unbound.
Address to unbind this socket from.
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A Reply socket can act as a server which receives requests from and sends replies to a Request socket. This socket type allows only an alternating sequence of receive() and subsequent send() calls. Each request received is fair-queued from among all clients, and each reply sent is routed to the client that issued the last request. If the original requester does not exist any more the reply is silently discarded.