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PERLER AVAR DRTECH TIMB JWANG

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4 non-PAUSE users.

Clinton Gormley

NAME

ElasticSearch::Transport - Base class for communicating with ElasticSearch

DESCRIPTION

ElasticSearch::Transport is a base class for the modules which communicate with the ElasticSearch server.

It handles failover to the next node in case the current node closes the connection. All requests are round-robin'ed to all live servers.

On the first request and every max_requests after that (default 10,000), the list of live nodes is automatically refreshed. This can be disabled by setting max_requests to 0.

Currently, the available backends are:

You shouldn't need to talk to the transport modules directly - everything happens via the main ElasticSearch class.

SYNOPSIS

    use ElasticSearch;
    my $e = ElasticSearch->new(
        servers     => 'search.foo.com:9200',
        transport   => 'httplite',
        timeout     => '10',
    );

    my $t = $e->transport;

    $t->max_requests(5)             # refresh_servers every 5 requests
    $t->protocol                    # eg 'http'
    $t->next_server                 # next node to use
    $t->current_server              # eg '127.0.0.1:9200' ie last used node
    $t->default_servers             # seed servers passed in to new()

    $t->servers                     # eg ['192.168.1.1:9200','192.168.1.2:9200']
    $t->servers(@servers);          # set new 'live' list

    $t->refresh_servers             # refresh list of live nodes

    $t->clear_clients               # clear all open clients

    $t->register('foo',$class)      # register new Transport backend

WHICH TRANSPORT SHOULD YOU USE

Although the thrift interface has the right buzzwords (binary, compact, sockets), the generated Perl code is very slow. Until that is improved, I recommend one of the http backends instead.

The httplite backend is about 30% faster than the default http backend, and will probably become the default after more testing in production.

Note: my experience with HTTP::Lite so far has been flawless - I'm just being cautious.

Also, just added the httptiny backend with HTTP::Tiny, which is 1% faster again than the httplite backend, but again needs more testing.

See also: http://www.elasticsearch.org/guide/reference/modules/http.html and http://www.elasticsearch.org/guide/reference/modules/thrift.html

SUBCLASSING TRANSPORT

If you want to add a new transport backend, then these are the methods that you should subclass:

init()

    $t->init($params)

Currently a no-op. Receives a HASH ref with the parameters passed in to new(), less servers, transport and timeout.

Any parameters specific to your module should be deleted from $params

send_request()

    $json = $t->send_request($server,$params)

    where $params = {
        method  => 'GET',
        cmd     => '/_cluster',
        qs      => { pretty => 1 },
        data    => '{ "foo": "bar"}',
    }

This must be overridden in the subclass - it is the method called to actually talk to the server.

See ElasticSearch::Transport::HTTP for an example implementation.

protocol()

    $t->protocol

This must return the protocol in use, eg "http" or "thrift". It is used to extract the list of bound addresses from ElasticSearch, eg http_address or thrift_address.

client()

    $client = $t->client($server)

Returns the client object used in "send_request()". The server param will look like "192.168.5.1:9200". It should store its clients in a PID specific slot in $t->{_client} as clear_clients() deletes this key.

See "client()" in ElasticSearch::Transport::HTTP and "client()" in ElasticSearch::Transport::Thrift for an example implementation.

Registering your Transport backend

You can register your Transport backend as follows:

    BEGIN {
        ElasticSearch::Transport->register('mytransport',__PACKAGE__);
    }

SEE ALSO

LICENSE AND COPYRIGHT

Copyright 2010 - 2011 Clinton Gormley.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.