zmq_bind(3) [debian man page]
ZMQ_BIND(3) 0MQ Manual ZMQ_BIND(3) NAME
zmq_bind - accept connections on a socket SYNOPSIS
int zmq_bind (void *socket, const char *endpoint); DESCRIPTION
The zmq_bind() function shall create an endpoint for accepting connections and bind it to the socket referenced by the socket argument. The endpoint argument is a string consisting of two parts as follows: transport://address. The transport part specifies the underlying transport protocol to use. The meaning of the address part is specific to the underlying transport protocol selected. The following transports are defined: inproc local in-process (inter-thread) communication transport, see zmq_inproc(7) ipc local inter-process communication transport, see zmq_ipc(7) tcp unicast transport using TCP, see zmq_tcp(7) pgm, epgm reliable multicast transport using PGM, see zmq_pgm(7) With the exception of ZMQ_PAIR sockets, a single socket may be connected to multiple endpoints using zmq_connect(), while simultaneously accepting incoming connections from multiple endpoints bound to the socket using zmq_bind(). Refer to zmq_socket(3) for a description of the exact semantics involved when connecting or binding a socket to multiple endpoints. RETURN VALUE
The zmq_bind() function shall return zero if successful. Otherwise it shall return -1 and set errno to one of the values defined below. ERRORS
EINVAL The endpoint supplied is invalid. EPROTONOSUPPORT The requested transport protocol is not supported. ENOCOMPATPROTO The requested transport protocol is not compatible with the socket type. EADDRINUSE The requested address is already in use. EADDRNOTAVAIL The requested address was not local. ENODEV The requested address specifies a nonexistent interface. ETERM The 0MQ context associated with the specified socket was terminated. ENOTSOCK The provided socket was invalid. EMTHREAD No I/O thread is available to accomplish the task. EXAMPLE
Binding a publisher socket to an in-process and a TCP transport. /* Create a ZMQ_PUB socket */ void *socket = zmq_socket (context, ZMQ_PUB); assert (socket); /* Bind it to a in-process transport with the address 'my_publisher' */ int rc = zmq_bind (socket, "inproc://my_publisher"); assert (rc == 0); /* Bind it to a TCP transport on port 5555 of the 'eth0' interface */ rc = zmq_bind (socket, "tcp://eth0:5555"); assert (rc == 0); SEE ALSO
zmq_connect(3) zmq_socket(3) zmq(7) AUTHORS
This manual page was written by the 0MQ community. 0MQ 2.2.0 04/04/2012 ZMQ_BIND(3)
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ZMQ_PGM(7) 0MQ Manual ZMQ_PGM(7) NAME
zmq_pgm - 0MQ reliable multicast transport using PGM SYNOPSIS
PGM (Pragmatic General Multicast) is a protocol for reliable multicast transport of data over IP networks. DESCRIPTION
0MQ implements two variants of PGM, the standard protocol where PGM datagrams are layered directly on top of IP datagrams as defined by RFC 3208 (the pgm transport) and "Encapsulated PGM" where PGM datagrams are encapsulated inside UDP datagrams (the epgm transport). The pgm and epgm transports can only be used with the ZMQ_PUB and ZMQ_SUB socket types. Further, PGM sockets are rate limited by default and incur a performance penalty when used over a loop-back interface. For details, refer to the ZMQ_RATE, ZMQ_RECOVERY_IVL and ZMQ_MCAST_LOOP options documented in zmq_setsockopt(3). Caution The pgm transport implementation requires access to raw IP sockets. Additional privileges may be required on some operating systems for this operation. Applications not requiring direct interoperability with other PGM implementations are encouraged to use the epgm transport instead which does not require any special privileges. ADDRESSING
A 0MQ address string consists of two parts as follows: transport://endpoint. The transport part specifies the underlying transport protocol to use. For the standard PGM protocol, transport shall be set to pgm. For the "Encapsulated PGM" protocol transport shall be set to epgm. The meaning of the endpoint part for both the pgm and epgm transport is defined below. Connecting a socket When connecting a socket to a peer address using zmq_connect() with the pgm or epgm transport, the endpoint shall be interpreted as an interface followed by a semicolon, followed by a multicast address, followed by a colon and a port number. An interface may be specified by either of the following: o The interface name as defined by the operating system. o The primary IPv4 address assigned to the interface, in its numeric representation. Note Interface names are not standardised in any way and should be assumed to be arbitrary and platform dependent. On Win32 platforms no short interface names exist, thus only the primary IPv4 address may be used to specify an interface. A multicast address is specified by an IPv4 multicast address in its numeric representation. WIRE FORMAT
Consecutive PGM datagrams are interpreted by 0MQ as a single continuous stream of data where 0MQ messages are not necessarily aligned with PGM datagram boundaries and a single 0MQ message may span several PGM datagrams. This stream of data consists of 0MQ messages encapsulated in frames as described in zmq_tcp(7). PGM datagram payload The following ABNF grammar represents the payload of a single PGM datagram as used by 0MQ: datagram = (offset data) offset = 2OCTET data = *OCTET In order for late joining consumers to be able to identify message boundaries, each PGM datagram payload starts with a 16-bit unsigned integer in network byte order specifying either the offset of the first message frame in the datagram or containing the value 0xFFFF if the datagram contains solely an intermediate part of a larger message. Note that offset specifies where the first message begins rather than the first message part. Thus, if there are trailing message parts at the beginning of the packet the offset ignores them and points to first initial message part in the packet. The following diagram illustrates the layout of a single PGM datagram payload: +------------------+----------------------+ | offset (16 bits) | data | +------------------+----------------------+ The following diagram further illustrates how three example 0MQ frames are laid out in consecutive PGM datagram payloads: First datagram payload +--------------+-------------+---------------------+ | Frame offset | Frame 1 | Frame 2, part 1 | | 0x0000 | (Message 1) | (Message 2, part 1) | +--------------+-------------+---------------------+ Second datagram payload +--------------+---------------------+ | Frame offset | Frame 2, part 2 | | 0xFFFF | (Message 2, part 2) | +--------------+---------------------+ Third datagram payload +--------------+----------------------------+-------------+ | Frame offset | Frame 2, final 8 bytes | Frame 3 | | 0x0008 | (Message 2, final 8 bytes) | (Message 3) | +--------------+----------------------------+-------------+ EXAMPLE
Connecting a socket. /* Connecting to the multicast address 239.192.1.1, port 5555, */ /* using the first Ethernet network interface on Linux */ /* and the Encapsulated PGM protocol */ rc = zmq_connect(socket, "epgm://eth0;239.192.1.1:5555"); assert (rc == 0); /* Connecting to the multicast address 239.192.1.1, port 5555, */ /* using the network interface with the address 192.168.1.1 */ /* and the standard PGM protocol */ rc = zmq_connect(socket, "pgm://192.168.1.1;239.192.1.1:5555"); assert (rc == 0); SEE ALSO
zmq_connect(3) zmq_setsockopt(3) zmq_tcp(7) zmq_ipc(7) zmq_inproc(7) zmq(7) AUTHORS
This manual page was written by the 0MQ community. 0MQ 2.2.0 04/04/2012 ZMQ_PGM(7)