NAME

Kafka::Message - Interface to the Kafka message properties.

VERSION

This documentation refers to "Kafka::Message" version 0.8010 .

SYNOPSIS

    use 5.010;
    use strict;
    use warnings;

    use Kafka qw(
        $DEFAULT_MAX_BYTES
    );
    use Kafka::Connection;
    use Kafka::Consumer;

    #-- Connection
    my $connection = Kafka::Connection->new( host => 'localhost' );

    #-- Consumer
    my $consumer = Kafka::Consumer->new( Connection  => $connection );

    # The Kafka consumer response has an ARRAY reference type.
    # For the fetch response array has the class name Kafka::Message elements.

    # Consuming messages
    my $messages = $consumer->fetch(
        'mytopic',          # topic
        0,                  # partition
        0,                  # offset
        $DEFAULT_MAX_BYTES  # Maximum size of MESSAGE(s) to receive
    );
    if ( $messages ) {
        foreach my $message ( @$messages ) {
            if( $message->valid ) {
                say 'key        : ', $message->key;
                say 'payload    : ', $message->payload;
                say 'offset     : ', $message->offset;
                say 'next_offset: ', $message->next_offset;
            } else {
                say 'error      : ', $message->error;
            }
        }
    }

    # Closes and cleans up
    undef $consumer;
    undef $connection;

DESCRIPTION

This module is not intended to be used by the end user.

Kafka::Message class implements API for Kafka message.

"fetch" method of the Consumer client returns reference to an array of objects of this class.

The main features of the "Kafka::Message" class are:

•: Represents Apache Kafka Message structure. Description of the structure is available at <https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Messagesets>

CONSTRUCTOR

"new ( \%arg )"

Creates a new "Kafka::Message" object. "new()" takes an argument - HASH reference with the message attributes corresponding to accessors.

METHODS

"payload"

A simple message received from the Apache Kafka server.

"key"

The key is an optional message key that was used for partition assignment. The key can be an empty string.

"valid"

Boolean value: indicates whether received message is valid or not.

"error"

A description why message is invalid.

"offset"

The offset of the message in the Apache Kafka server.

"next_offset"

The offset of the next message in the Apache Kafka server.

"Attributes"

This holds metadata attributes about the message. The lowest 2 bits contain the compression codec used for the message. The other bits are currently unused.

"HighwaterMarkOffset"

The offset at the end of the log for this partition. This can be used by the client to determine how many messages behind the end of the log they are.

"MagicByte"

This is version id used to allow backwards compatible evolution of the message binary format.

DIAGNOSTICS

In order to achieve better performance, constructor of this module does not perform validation of arguments.

SOURCE CODE

Kafka package is hosted on GitHub: <https://github.com/TrackingSoft/Kafka>

AUTHOR

Sergey Gladkov, <sgladkov@trackingsoft.com>

CONTRIBUTORS

Alexander Solovey

Jeremy Jordan

Sergiy Zuban

Vlad Marchenko

COPYRIGHT AND LICENSE

This package is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic at <http://dev.perl.org/licenses/artistic.html>.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.