NAME

ZMQ::LibZMQ3 - A libzmq 3.x wrapper for Perl

SYNOPSIS

    use ZMQ::LibZMQ;

    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

The ZMQ::LibZMQ3 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 0MQ.

Note that this is a wrapper for libzmq 2.x. For 3.x, you need to check ZMQ::LibZMQ3

BASIC USAGE

To start using ZMQ::LibZMQ3, you need to create a context object, then as many ZMQ::LibZMQ3::Socket obects as you need:

    my $ctxt = zmq_init;
    my $socket = zmq_socket( $ctxt, ... options );

You need to call zmq_bind() or zmq_connect() on the socket, depending on your usage. For example on a typical server-client model you would write on the server side:

    zmq_bind( $socket, "tcp://127.0.0.1:9999" );

and on the client side:

    zmq_connect( $socket, "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::LibZMQ3::Message object or a Perl string.

    # the following two send() calls are equivalent
    my $msg = zmq_msg_init_data( "a simple message" );
    zmq_send( $socket, $msg );
    
    zmq_send( $socket, "a simple message" ); 

In most cases using ZMQ::LibZMQ3::Message is redundunt, so you will most likely use the string version.

To receive, simply call zmq_recv() on the socket

    my $msg = zmq_recv( $socket );

The received message is an instance of ZMQ::LibZMQ3::Message object, and you can access the content held in the message via the data() method:

    my $data = zmq_msg_data( $msg );

ASYNCHRONOUS I/O WITH ZEROMQ

By default 0MQ 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::LibZMQ3 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

0MQ works on both multi-process and multi-threaded use cases, but you need to be careful bout sharing ZMQ::LibZMQ3 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

$value = zmq_getsockopt( $socket, $option )

Gets the value of the specified option.

If the particular version of ZMQ::LibZMQ3 does not implement the named socket option, an exception will be thrown:

    /* barfs, because we don't know what type this new option is */
    zmq_getsockopt( $socket, ZMQ_NEW_SHINY_OPTION );
    

In this case you can either use ZMQ::Constants, or you can use one of the utility functions that ZMQ::LibZMQ3 provides.

Using ZMQ::Constants

ZMQ::LibZMQ3 internally refers to ZMQ::Constants to learn about the type of a socket option. You can easily add new constants to this map:

    use ZMQ::Constants;
    ZMQ::Constants::add_sockopt_type( "int" => ZMQ_NEW_SHINY_OPTION );

Using utilities in ZMQ::LibZMQ3

    /* say you know that the value is an int, int64, uint64, or char *
       by reading the zmq docs */
    $int    = zmq_getsockopt_int( $socket, ZMQ_NEW_SHINY_OPTION );
    $int64  = zmq_getsockopt_int64( $socket, ZMQ_NEW_SHINY_OPTION );
    $uint64 = zmq_getsockopt_uint64( $socket, ZMQ_NEW_SHINY_OPTION );
    $string = zmq_getsockopt_string( $socket, ZMQ_NEW_SHINY_OPTION );

$status = zmq_setsockopt( $socket, $option, $value )

Sets the value of the specified option. Returns the status.

See zmq_getsockopt() if you have problems with ZMQ::LibZMQ3 not knowing the type of the option.

zmq_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 $version_string = ZMQ::LibZMQ3::zmq_version();
    my ($major, $minor, $patch) = ZMQ::LibZMQ3::zmq_version();

zmq_device($type, $sock1, $sock2)

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 ZMQ::LibZMQ3 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 3.1.1. 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

http://zeromq.org

http://github.com/lestrrat/p5-ZMQ

AUTHOR

Daisuke Maki <daisuke@endeworks.jp>

Steffen Mueller, <smueller@cpan.org>

COPYRIGHT AND LICENSE

The ZMQ::LibZMQ3 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::LibZMQ3

perl -MCPAN -e shell
install ZMQ::LibZMQ3