NAME

ZMQ - A libzmq wrapper for Perl

SYNOPSIS ( HIGH-LEVEL API )

    # echo server
    use ZMQ qw/:all/;

    my $cxt = ZMQ::Context->new;
    my $sock = $cxt->socket(ZMQ_REP);
    $sock->bind($addr);
  
    my $msg;
    foreach (1..$roundtrip_count) {
        $msg = $sock->recvmsg();
        $sock->sendmsg($msg);
    }

SYNOPSIS ( LOW-LEVEL API )

    use ZMQ::Raw;

    my $ctxt = zmq_init($threads);
    my $rv   = zmq_term($ctxt);

    my $rv   = zmq_connect( $socket, $where );
    my $rv   = zmq_bind( $socket, $where );
    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_sendmsg( $sock, $msg, $flags );
    my $msg  = zmq_recvmsg( $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

The ZMQ 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 ZMQ.

CLASS WALKTHROUGH

ZMQ::Raw

Use ZMQ::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.

ZMQ::Constants

ZMQ::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.

ZMQ::Context

ZMQ::Socket

ZMQ::Message

ZMQ::Context, ZMQ::Socket, ZMQ::Message contain the high-level, more perl-ish interface to the zeromq functionalities.

ZMQ

Loading ZMQ will make the ZMQ::Context, ZMQ::Socket, and ZMQ::Message classes available as well.

BASIC USAGE

To start using ZMQ, you need to create a context object, then as many ZMQ::Socket as you need:

    my $ctxt = ZMQ::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 ZMQ::Message object or a Perl string.

    my $msg = ZMQ::Message->new( "a simple message" );
    $socket->sendmsg( $msg );

    $socket->send( "a simple message" ); 

In most cases using ZMQ::Message is redundunt, so you will most likely use the string version.

To receive, simply call recvmsg() on the socket

    my $msg = $socket->recvmsg;

The received message is an instance of ZMQ::Message object, and you can access the content held in the message via the data() method:

    my $data = $msg->data;

Or, you may choose use recv(), if you know the amount of data you wanted to read

    my $buf;
    my $length = ...;
    my $n_read = $socket->recv( $buf, $length );

ASYNCHRONOUS I/O WITH ZEROMQ

By default ZMQ 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 ZMQ 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_recvmsg( $socket, ZMQ_RCVMORE ) ) {
            # do something with $msg;
        }
        undef $w;
    };

NOTES ON MULTI-PROCESS and MULTI-THREADED USAGE

ZMQ works on both multi-process and multi-threaded use cases, but you need to be careful bout sharing ZMQ 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 $version_string = ZMQ::version();
    my ($major, $minor, $patch) = ZMQ::version();

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

Please put this in your bug report.

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

ZMQ::Raw, ZMQ::Context, ZMQ::Socket, ZMQ::Message

http://zeromq.org

http://github.com/lestrrat/ZMQ-Perl

AUTHOR

Daisuke Maki <daisuke@endeworks.jp>

Steffen Mueller, <smueller@cpan.org>

COPYRIGHT AND LICENSE

The ZMQ 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.

cpanm ZMQ

perl -MCPAN -e shell
install ZMQ