| ZeroMQ::Socket(3pm) - phpMan
ZeroMQ::Socket(3pm) User Contributed Perl Documentation ZeroMQ::Socket(3pm)
NAME
ZeroMQ::Socket - A 0MQ Socket object
SYNOPSIS
use ZeroMQ qw/:all/;
my $cxt = ZeroMQ::Context->new;
my $sock = ZeroMQ::Socket->new($cxt, ZMQ_REP);
DESCRIPTION
0MQ sockets present an abstraction of a asynchronous message queue, with the exact
queueing semantics depending on the socket type in use.
Key differences to conventional sockets
Quoting the 0MQ manual:
Generally speaking, conventional sockets present a synchronous interface to either
connection-oriented reliable byte streams ("SOCK_STREAM"), or connection-less unreliable
datagrams ("SOCK_DGRAM"). In comparison, 0MQ sockets present an abstraction of an
asynchronous message queue, with the exact queueing semantics depending on the socket type
in use. Where conventional sockets transfer streams of bytes or discrete datagrams, 0MQ
sockets transfer discrete messages.
0MQ sockets being asynchronous means that the timings of the physical connection setup and
teardown, reconnect and effective delivery are transparent to the user and organized by
0MQ itself. Further, messages may be queued in the event that a peer is unavailable to
receive them.
Conventional sockets allow only strict one-to-one (two peers), many-to-one (many clients,
one server), or in some cases one-to-many (multicast) relationships. With the exception of
"ZMQ_PAIR", 0MQ sockets may be connected to multiple endpoints using c<connect()>, while
simultaneously accepting incoming connections from multiple endpoints bound to the socket
using c<bind()>, thus allowing many-to-many relationships.
Socket types
For detailed explanations of the socket types, check the official 0MQ documentation. This
is just a short list of types:
Request-reply pattern
The "ZMQ_REQ" type is for the client that sends, then receives. The "ZMQ_REP" type is
for the server that receives a message, then answers.
Publish-subscribe pattern
The "ZMQ_PUB" type is for publishing messages to an arbitrary number of subscribers
only. The "ZMQ_SUB" type is for subscribers that receive messages.
Pipeline pattern
The "ZMQ_UPSTREAM" socket type sends messages in a pipeline pattern. "ZMQ_DOWNSTREAM"
receives them.
Exclusive pair pattern
The "ZMQ_PAIR" type allows bidirectional message passing between two participants.
METHODS
new
Creates a new "ZeroMQ::Socket".
First argument must be the ZeroMQ::Context in which the socket is to live. Second argument
is the socket type.
The newly created socket is initially unbound, and not associated with any endpoints. In
order to establish a message flow a socket must first be connected to at least one
endpoint with the "connect" method or at least one endpoint must be created for accepting
incoming connections with the "bind" method.
bind
The "bind($endpoint)" method function creates an endpoint for accepting connections and
binds it to the socket.
Quoting the 0MQ manual: The endpoint argument is a string consisting of two parts as
follows: "transport://address". The transport part specifies the underlying transport
protocol to use. The meaning of the address part is specific to the underlying transport
protocol selected.
The following transports are defined. Refer to the 0MQ manual for details.
inproc
Local in-process (inter-thread) communication transport.
ipc
Local inter-process communication transport.
tcp
Unicast transport using TCP.
pgm, epgm
Reliable multicast transport using PGM.
With the exception of "ZMQ_PAIR" sockets, a single socket may be connected to multiple
endpoints using "connect($endpoint)", while simultaneously accepting incoming connections
from multiple endpoints bound to the socket using "bind($endpoint")>. The exact semantics
depend on the socket type.
connect
Connect to an existing endpoint. Takes an enpoint string as argument, see the
documentation for "bind($endpoint)" above.
close
send
The "send($msg, $flags)" method queues the given message to be sent to the socket. The
flags argument is a combination of the flags defined below.
send_as( $type, $message, $flags )
ZMQ_NOBLOCK
Specifies that the operation should be performed in non-blocking mode. If the message
cannot be queued on the socket, the "send()" method fails with errno set to EAGAIN.
ZMQ_SNDMORE
Specifies that the message being sent is a multi-part message, and that further message
parts are to follow. Refer to the 0MQ manual for details regarding multi-part messages.
recv
The "my $msg = $sock->recv($flags)" method receives a message from the socket and returns
it as a new "ZeroMQ::Message" object. If there are no messages available on the specified
socket the "recv()" method blocks until the request can be satisfied. The flags argument
is a combination of the flags defined below.
recv_as( $type, $flags )
ZMQ_NOBLOCK
Specifies that the operation should be performed in non-blocking mode. If there are no
messages available on the specified socket, the "$sock->recv(ZMQ_NOBLOCK)" method call
returns "undef" and sets $ERRNO to "EAGAIN".
getsockopt
The "my $optval = $sock->getsockopt(ZMQ_SOME_OPTION)" method call retrieves the value for
the given socket option.
The following options can be retrieved. For a full explanation of the options, please
refer to the 0MQ manual.
ZMQ_RCVMORE: More message parts to follow
ZMQ_HWM: Retrieve high water mark
ZMQ_SWAP: Retrieve disk offload size
ZMQ_AFFINITY: Retrieve I/O thread affinity
ZMQ_IDENTITY: Retrieve socket identity
ZMQ_RATE: Retrieve multicast data rate
ZMQ_RECOVERY_IVL: Get multicast recovery interval
ZMQ_MCAST_LOOP: Control multicast loopback
ZMQ_SNDBUF: Retrieve kernel transmit buffer size
ZMQ_RCVBUF: Retrieve kernel receive buffer size
setsockopt
The "$sock->setsockopt(ZMQ_SOME_OPTION, $value)" method call sets the specified option to
the given value.
The following socket options can be set. For details, please refer to the 0MQ manual:
ZMQ_HWM: Set high water mark
ZMQ_SWAP: Set disk offload size
ZMQ_AFFINITY: Set I/O thread affinity
ZMQ_IDENTITY: Set socket identity
ZMQ_SUBSCRIBE: Establish message filter
ZMQ_UNSUBSCRIBE: Remove message filter
ZMQ_RATE: Set multicast data rate
ZMQ_RECOVERY_IVL: Set multicast recovery interval
ZMQ_MCAST_LOOP: Control multicast loopback
ZMQ_SNDBUF: Set kernel transmit buffer size
ZMQ_RCVBUF: Set kernel receive buffer size
CAVEATS
"ZeroMQ::Socket" objects aren't thread safe due to the underlying library. Therefore, they
are currently not cloned when a new Perl ithread is spawned. The variables in the new
thread that contained the socket in the parent thread will be a scalar reference to
"undef" in the new thread. This makes the Perl wrapper thread safe (i.e. no segmentation
faults).
SEE ALSO
ZeroMQ, ZeroMQ::Socket
<http://zeromq.org>
ExtUtils::XSpp, Module::Build::WithXSpp
AUTHOR
Daisuke Maki <daisuke AT endeworks.jp>
Steffen Mueller, <smueller AT cpan.org>
COPYRIGHT AND LICENSE
The ZeroMQ module is
Copyright (C) 2010 by Daisuke Maki
This library is free software; you can redistribute it and/or modify it under the same
terms as Perl itself, either Perl version 5.8.0 or, at your option, any later version of
Perl 5 you may have available.
perl v5.20.0 2012-10-16 ZeroMQ::Socket(3pm)
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