zmq_socket_monitor_versioned(3) =============================== NAME ---- zmq_socket_monitor_versioned - monitor socket events SYNOPSIS -------- *int zmq_socket_monitor_versioned (void '*socket', char '*endpoint', uint64_t 'events', int 'event_version');* DESCRIPTION ----------- The _zmq_socket_monitor_versioned()_ method lets an application thread track socket events (like connects) on a ZeroMQ socket. Each call to this method creates a 'ZMQ_PAIR' socket and binds that to the specified inproc:// 'endpoint'. To collect the socket events, you must create your own 'ZMQ_PAIR' socket, and connect that to the endpoint. The 'events' argument is a bitmask of the socket events you wish to monitor, see 'Supported events' below. To monitor all events for a version, use the event value ZMQ_EVENT_ALL_V, e.g. ZMQ_EVENT_ALL_V1. For non-DRAFT event versions, this value will not change in the future, so new event types will only be added in new versions (note that this is a change over zmq_socket_monitor and the unversioned ZMQ_EVENT_ALL). Note that event_version 2 is currently in DRAFT mode. The protocol may be changed at any time for event_versions in DRAFT. ZMQ_CURRENT_EVENT_VERSION and ZMQ_CURRENT_EVENT_VERSION_DRAFT are always defined to the most recent stable or DRAFT event version, which are currently 1 resp. 2 This page describes the protocol for 'event_version' 2 only. For the protocol used with 'event_version' 1, please refer to linkzmq:zmq_socket_monitor[3]. Each event is sent in multiple frames. The first frame contains an event number (64 bits). The number and content of further frames depend on this event number. Unless it is specified differently, the second frame contains an event value (64 bits) that provides additional data according to the event number. Some events might define additional value frames following the second one. The third and fourth frames contain strings that specifies the affected connection or endpoint. The third frame contains a string denoting the local endpoint, while the fourth frame contains a string denoting the remote endpoint. Either of these may be empty, depending on the event type and whether the connection uses a bound or connected local endpoint. Note that the format of the second and further frames, and also the number of frames, may be different for events added in the future. ---- Monitoring events are only generated by some transports: At the moment these are SOCKS, TCP, IPC, and TIPC. Note that it is not an error to call 'zmq_socket_monitor_versioned' on a socket that is connected or bound to some other transport, as this may not be known at the time 'zmq_socket_monitor_versioned' is called. Also, a socket can be connected/bound to multiple endpoints using different transports. ---- Supported events (v1) ---------------- ZMQ_EVENT_CONNECTED ~~~~~~~~~~~~~~~~~~~ The socket has successfully connected to a remote peer. The event value is the file descriptor (FD) of the underlying network socket. Warning: there is no guarantee that the FD is still valid by the time your code receives this event. ZMQ_EVENT_CONNECT_DELAYED ~~~~~~~~~~~~~~~~~~~~~~~~~ A connect request on the socket is pending. The event value is unspecified. ZMQ_EVENT_CONNECT_RETRIED ~~~~~~~~~~~~~~~~~~~~~~~~~ A connect request failed, and is now being retried. The event value is the reconnect interval in milliseconds. Note that the reconnect interval is recalculated for each retry. ZMQ_EVENT_LISTENING ~~~~~~~~~~~~~~~~~~~ The socket was successfully bound to a network interface. The event value is the FD of the underlying network socket. Warning: there is no guarantee that the FD is still valid by the time your code receives this event. ZMQ_EVENT_BIND_FAILED ~~~~~~~~~~~~~~~~~~~~~ The socket could not bind to a given interface. The event value is the errno generated by the system bind call. ZMQ_EVENT_ACCEPTED ~~~~~~~~~~~~~~~~~~ The socket has accepted a connection from a remote peer. The event value is the FD of the underlying network socket. Warning: there is no guarantee that the FD is still valid by the time your code receives this event. ZMQ_EVENT_ACCEPT_FAILED ~~~~~~~~~~~~~~~~~~~~~~~ The socket has rejected a connection from a remote peer. The event value is the errno generated by the accept call. ZMQ_EVENT_CLOSED ~~~~~~~~~~~~~~~~ The socket was closed. The event value is the FD of the (now closed) network socket. ZMQ_EVENT_CLOSE_FAILED ~~~~~~~~~~~~~~~~~~~~~~ The socket close failed. The event value is the errno returned by the system call. Note that this event occurs only on IPC transports. ZMQ_EVENT_DISCONNECTED ~~~~~~~~~~~~~~~~~~~~~~ The socket was disconnected unexpectedly. The event value is the FD of the underlying network socket. Warning: this socket will be closed. ZMQ_EVENT_MONITOR_STOPPED ~~~~~~~~~~~~~~~~~~~~~~~~~ Monitoring on this socket ended. ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Unspecified error during handshake. The event value is an errno. ZMQ_EVENT_HANDSHAKE_SUCCEEDED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ZMTP security mechanism handshake succeeded. The event value is unspecified. ZMQ_EVENT_HANDSHAKE_FAILED_PROTOCOL ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ZMTP security mechanism handshake failed due to some mechanism protocol error, either between the ZMTP mechanism peers, or between the mechanism server and the ZAP handler. This indicates a configuration or implementation error in either peer resp. the ZAP handler. The event value is one of the ZMQ_PROTOCOL_ERROR_* values: ZMQ_PROTOCOL_ERROR_ZMTP_UNSPECIFIED ZMQ_PROTOCOL_ERROR_ZMTP_UNEXPECTED_COMMAND ZMQ_PROTOCOL_ERROR_ZMTP_INVALID_SEQUENCE ZMQ_PROTOCOL_ERROR_ZMTP_KEY_EXCHANGE ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_UNSPECIFIED ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_MESSAGE ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_HELLO ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_INITIATE ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_ERROR ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_READY ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_WELCOME ZMQ_PROTOCOL_ERROR_ZMTP_INVALID_METADATA ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC ZMQ_PROTOCOL_ERROR_ZMTP_MECHANISM_MISMATCH ZMQ_PROTOCOL_ERROR_ZAP_UNSPECIFIED ZMQ_PROTOCOL_ERROR_ZAP_MALFORMED_REPLY ZMQ_PROTOCOL_ERROR_ZAP_BAD_REQUEST_ID ZMQ_PROTOCOL_ERROR_ZAP_BAD_VERSION ZMQ_PROTOCOL_ERROR_ZAP_INVALID_STATUS_CODE ZMQ_PROTOCOL_ERROR_ZAP_INVALID_METADATA ZMQ_EVENT_HANDSHAKE_FAILED_AUTH ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ZMTP security mechanism handshake failed due to an authentication failure. The event value is the status code returned by the ZAP handler (i.e. 300, 400 or 500). RETURN VALUE ------------ The _zmq_socket_monitor()_ function returns a value of 0 or greater if successful. Otherwise it returns `-1` and sets 'errno' to one of the values defined below. ERRORS ------ *ETERM*:: The 0MQ 'context' associated with the specified 'socket' was terminated. *EPROTONOSUPPORT*:: The transport protocol of the monitor 'endpoint' is not supported. Monitor sockets are required to use the inproc:// transport. *EINVAL*:: The monitor 'endpoint' supplied does not exist. EXAMPLE ------- .Monitoring client and server sockets ---- // Read one event off the monitor socket; return value and address // by reference, if not null, and event number by value. Returns -1 // in case of error. static uint64_t get_monitor_event (void *monitor, uint64_t *value, char **local_address, char **remote_address) { // First frame in message contains event number zmq_msg_t msg; zmq_msg_init (&msg); if (zmq_msg_recv (&msg, monitor, 0) == -1) return -1; // Interrupted, presumably assert (zmq_msg_more (&msg)); uint64_t event; memcpy (&event, zmq_msg_data (&msg), sizeof (event)); zmq_msg_close (&msg); // Second frame to Nth frame (depends on the event) in message // contains event value zmq_msg_init (&msg); if (zmq_msg_recv (&msg, monitor, 0) == -1) return -1; // Interrupted, presumably assert (zmq_msg_more (&msg)); if (value_) memcpy (value_, zmq_msg_data (&msg), sizeof *value_); zmq_msg_close (&msg); // Third frame in message contains local address zmq_msg_init (&msg); if (zmq_msg_recv (&msg, monitor, 0) == -1) return -1; // Interrupted, presumably assert (zmq_msg_more (&msg)); if (local_address_) { uint8_t *data = (uint8_t *) zmq_msg_data (&msg); size_t size = zmq_msg_size (&msg); *local_address_ = (char *) malloc (size + 1); memcpy (*local_address_, data, size); (*local_address_)[size] = 0; } zmq_msg_close (&msg); // Fourth frame in message contains remote address zmq_msg_init (&msg); if (zmq_msg_recv (&msg, monitor, 0) == -1) return -1; // Interrupted, presumably assert (!zmq_msg_more (&msg)); if (remote_address_) { uint8_t *data = (uint8_t *) zmq_msg_data (&msg); size_t size = zmq_msg_size (&msg); *remote_address_ = (char *) malloc (size + 1); memcpy (*remote_address_, data, size); (*remote_address_)[size] = 0; } zmq_msg_close (&msg); return event; } int main (void) { void *ctx = zmq_ctx_new (); assert (ctx); // We'll monitor these two sockets void *client = zmq_socket (ctx, ZMQ_DEALER); assert (client); void *server = zmq_socket (ctx, ZMQ_DEALER); assert (server); // Socket monitoring only works over inproc:// int rc = zmq_socket_monitor_versioned (client, "tcp://127.0.0.1:9999", 0, 2); assert (rc == -1); assert (zmq_errno () == EPROTONOSUPPORT); // Monitor all events on client and server sockets rc = zmq_socket_monitor_versioned (client, "inproc://monitor-client", ZMQ_EVENT_ALL, 2); assert (rc == 0); rc = zmq_socket_monitor_versioned (server, "inproc://monitor-server", ZMQ_EVENT_ALL, 2); assert (rc == 0); // Create two sockets for collecting monitor events void *client_mon = zmq_socket (ctx, ZMQ_PAIR); assert (client_mon); void *server_mon = zmq_socket (ctx, ZMQ_PAIR); assert (server_mon); // Connect these to the inproc endpoints so they'll get events rc = zmq_connect (client_mon, "inproc://monitor-client"); assert (rc == 0); rc = zmq_connect (server_mon, "inproc://monitor-server"); assert (rc == 0); // Now do a basic ping test rc = zmq_bind (server, "tcp://127.0.0.1:9998"); assert (rc == 0); rc = zmq_connect (client, "tcp://127.0.0.1:9998"); assert (rc == 0); bounce (client, server); // Close client and server close_zero_linger (client); close_zero_linger (server); // Now collect and check events from both sockets int event = get_monitor_event (client_mon, NULL, NULL); if (event == ZMQ_EVENT_CONNECT_DELAYED) event = get_monitor_event (client_mon, NULL, NULL); assert (event == ZMQ_EVENT_CONNECTED); event = get_monitor_event (client_mon, NULL, NULL); assert (event == ZMQ_EVENT_MONITOR_STOPPED); // This is the flow of server events event = get_monitor_event (server_mon, NULL, NULL); assert (event == ZMQ_EVENT_LISTENING); event = get_monitor_event (server_mon, NULL, NULL); assert (event == ZMQ_EVENT_ACCEPTED); event = get_monitor_event (server_mon, NULL, NULL); assert (event == ZMQ_EVENT_CLOSED); event = get_monitor_event (server_mon, NULL, NULL); assert (event == ZMQ_EVENT_MONITOR_STOPPED); // Close down the sockets close_zero_linger (client_mon); close_zero_linger (server_mon); zmq_ctx_term (ctx); return 0 ; } ---- SEE ALSO -------- linkzmq:zmq[7] AUTHORS ------- This page was written by the 0MQ community. 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