NAME¶
ZeroMQ - A ZeroMQ2 wrapper for Perl (DEPRECATED)
SYNOPSIS ( HIGH-LEVEL API )¶
# echo server
use ZeroMQ qw/:all/;
my $cxt = ZeroMQ::Context->new;
my $sock = $cxt->socket(ZMQ_REP);
$sock->bind($addr);
my $msg;
foreach (1..$roundtrip_count) {
$msg = $sock->recv();
$sock->send($msg);
}
# json (if JSON.pm is available)
$sock->send_as( json => { foo => "bar" } );
my $thing = $sock->recv_as( "json" );
# custom serialization
ZeroMQ::register_read_type(myformat => sub { ... });
ZeroMQ::register_write_type(myformat => sub { .. });
$sock->send_as( myformat => $data ); # serialize using above callback
my $thing = $sock->recv_as( "myformat" );
SYNOPSIS ( LOW-LEVEL API )¶
use ZeroMQ::Raw;
my $ctxt = zmq_init($threads);
my $rv = zmq_term($ctxt);
my $msg = zmq_msg_init();
my $msg = zmq_msg_init_size( $size );
my $msg = zmq_msg_init_data( $data );
my $rv = zmq_msg_close( $msg );
my $rv = zmq_msg_move( $dest, $src );
my $rv = zmq_msg_copy( $dest, $src );
my $data = zmq_msg_data( $msg );
my $size = zmq_msg_size( $msg);
my $sock = zmq_socket( $ctxt, $type );
my $rv = zmq_close( $sock );
my $rv = zmq_setsockopt( $socket, $option, $value );
my $val = zmq_getsockopt( $socket, $option );
my $rv = zmq_bind( $sock, $addr );
my $rv = zmq_send( $sock, $msg, $flags );
my $msg = zmq_recv( $sock, $flags );
INSTALLATION¶
If you have libzmq registered with pkg-config:
perl Makefile.PL
make
make test
make install
If you don't have pkg-config, and libzmq is installed under /usr/local/libzmq:
ZMQ_HOME=/usr/local/libzmq \
perl Makefile.PL
make
make test
make install
If you want to customize include directories and such:
ZMQ_INCLUDES=/path/to/libzmq/include \
ZMQ_LIBS=/path/to/libzmq/lib \
ZMQ_H=/path/to/libzmq/include/zmq.h \
perl Makefile.PL
make
make test
make install
If you want to compile with debugging on:
perl Makefile.PL -g
DESCRIPTION¶
Please note that this module has been DEPRECATED in favor of ZMQ::LibZMQ2,
ZMQ::LibZMQ3, and ZMQ. see
https://github.com/lestrrat/p5-ZMQ and other CPAN
pages.
The "ZeroMQ" module is a wrapper of the 0MQ message passing library
for Perl. It's a thin wrapper around the C API. Please read
<
http://zeromq.org> for more details on ZeroMQ.
CLASS WALKTHROUGH¶
- ZeroMQ::Raw
- Use ZeroMQ::Raw to get access to the C API such as "zmq_init",
"zmq_socket", et al. Functions provided in this low level API
should follow the C API exactly.
- ZeroMQ::Constants
- ZeroMQ::Constants contains all of the constants that are known to be
extractable from zmq.h. Do note that sometimes the list changes due to
additions/deprecations in the underlying zeromq2 library. We try to do our
best to make things available (at least to warn you that some symbols are
deprecated), but it may not always be possible.
- ZeroMQ::Context
- ZeroMQ::Socket
- ZeroMQ::Message
- ZeroMQ::Context, ZeroMQ::Socket, ZeroMQ::Message contain the high-level,
more perl-ish interface to the zeromq functionalities.
- ZeroMQ
- Loading "ZeroMQ" will make the ZeroMQ::Context, ZeroMQ::Socket,
and ZeroMQ::Message classes available as well.
BASIC USAGE¶
To start using ZeroMQ, you need to create a context object, then as many
ZeroMQ::Socket as you need:
my $ctxt = ZeroMQ::Context->new;
my $socket = $ctxt->socket( ... options );
You need to call "bind()" or "connect()" on the socket,
depending on your usage. For example on a typical server-client model you
would write on the server side:
$socket->bind( "tcp://127.0.0.1:9999" );
and on the client side:
$socket->connect( "tcp://127.0.0.1:9999" );
The underlying zeromq library offers TCP, multicast, in-process, and ipc
connection patterns. Read the zeromq manual for more details on other ways to
setup the socket.
When sending data, you can either pass a ZeroMQ::Message object or a Perl
string.
# the following two send() calls are equivalent
my $msg = ZeroMQ::Message->new( "a simple message" );
$socket->send( $msg );
$socket->send( "a simple message" );
In most cases using ZeroMQ::Message is redundunt, so you will most likely use
the string version.
To receive, simply call "recv()" on the socket
my $msg = $socket->recv;
The received message is an instance of ZeroMQ::Message object, and you can
access the content held in the message via the "data()" method:
my $data = $msg->data;
SERIALIZATION¶
ZeroMQ.pm comes with a simple serialization/deserialization mechanism.
To serialize, use "register_write_type()" to register a name and an
associated callback to serialize the data. For example, for JSON we do the
following (this is already done for you in ZeroMQ.pm if you have JSON.pm
installed):
use JSON ();
ZeroMQ::register_write_type('json' => \&JSON::encode_json);
ZeroMQ::register_read_type('json' => \&JSON::decode_json);
Then you can use "send_as()" and "recv_as()" to specify the
serialization type as the first argument:
my $ctxt = ZeroMQ::Context->new();
my $sock = $ctxt->socket( ZMQ_REQ );
$sock->send_as( json => $complex_perl_data_structure );
The otherside will receive a JSON encoded data. The receivind side can be
written as:
my $ctxt = ZeroMQ::Context->new();
my $sock = $ctxt->socket( ZMQ_REP );
my $complex_perl_data_structure = $sock->recv_as( 'json' );
If you have JSON.pm (must be 2.00 or above), then the JSON serializer /
deserializer is automatically enabled. If you want to tweak the serializer
option, do something like this:
my $coder = JSON->new->utf8->pretty; # pretty print
ZeroMQ::register_write_type( json => sub { $coder->encode($_[0]) } );
ZeroMQ::register_read_type( json => sub { $coder->decode($_[0]) } );
Note that this will have a GLOBAL effect. If you want to change only your
application, use a name that's different from 'json'.
ASYNCHRONOUS I/O WITH ZEROMQ¶
By default ZeroMQ comes with its own
zmq_poll() mechanism that can handle
non-blocking sockets. You can use this by calling zmq_poll with a list of
hashrefs:
zmq_poll([
{
fd => fileno(STDOUT),
events => ZMQ_POLLOUT,
callback => \&callback,
},
{
socket => $zmq_socket,
events => ZMQ_POLLIN,
callback => \&callback
},
], $timeout );
Unfortunately this custom polling scheme doesn't play too well with AnyEvent.
As of zeromq2-2.1.0, you can use getsockopt to retrieve the underlying file
descriptor, so use that to integrate ZeroMQ and AnyEvent:
my $socket = zmq_socket( $ctxt, ZMQ_REP );
my $fh = zmq_getsockopt( $socket, ZMQ_FD );
my $w; $w = AE::io $fh, 0, sub {
while ( my $msg = zmq_recv( $socket, ZMQ_RCVMORE ) ) {
# do something with $msg;
}
undef $w;
};
NOTES ON MULTI-PROCESS and MULTI-THREADED USAGE¶
ZeroMQ works on both multi-process and multi-threaded use cases, but you need to
be careful bout sharing ZeroMQ objects.
For multi-process environments, you should not be sharing the context object.
Create separate contexts for each process, and therefore you shouldn't be
sharing the socket objects either.
For multi-thread environemnts, you can share the same context object. However
you cannot share sockets.
FUNCTIONS¶
version()¶
Returns the version of the underlying zeromq library that is being linked. In
scalar context, returns a dotted version string. In list context, returns a
3-element list of the version numbers:
my $version_string = ZeroMQ::version();
my ($major, $minor, $patch) = ZeroMQ::version();
device($type, $sock1, $sock2)¶
register_read_type($name, \&callback)¶
Register a read callback for a given $name. This is used in
"recv_as()". The callback receives the data received from the
socket.
register_write_type($name, \&callback)¶
Register a write callback for a given $name. This is used in
"send_as()" The callback receives the Perl structure given to
"send_as()"
DEBUGGING XS¶
If you see segmentation faults, and such, you need to figure out where the error
is occuring in order for the maintainers to figure out what happened. Here's a
very very brief explanation of steps involved.
First, make sure to compile ZeroMQ.pm with debugging on by specifying -g:
perl Makefile.PL -g
make
Then fire gdb:
gdb perl
(gdb) R -Mblib /path/to/your/script.pl
When you see the crash, get a backtrace:
(gdb) bt
CAVEATS¶
This is an early release. Proceed with caution, please report (or better yet:
fix) bugs you encounter.
This module has been tested againt
zeromq 2.1.4. Semantics of this module
rely heavily on the underlying zeromq version. Make sure you know which
version of zeromq you're working with.
SEE ALSO¶
ZeroMQ::Raw, ZeroMQ::Context, ZeroMQ::Socket, ZeroMQ::Message
<
http://zeromq.org>
<
http://github.com/lestrrat/ZeroMQ-Perl>
AUTHOR¶
Daisuke Maki "<daisuke@endeworks.jp>"
Steffen Mueller, "<smueller@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.