NAME
Search::Elasticsearch::Async - Async API for Elasticsearch using
Promises
VERSION
version 7.711001
SYNOPSIS
use Search::Elasticsearch::Async;
use Promises backend => ['AnyEvent'];
# Connect to localhost:9200:
my $e = Search::Elasticsearch::Async->new();
# Round-robin between two nodes:
my $e = Search::Elasticsearch::Async->new(
nodes => [
'search1:9200',
'search2:9200'
]
);
# Connect to cluster at search1:9200, sniff all nodes and round-robin between them:
my $e = Search::Elasticsearch::Async->new(
nodes => 'search1:9200',
cxn_pool => 'Async::Sniff'
);
# Index a document:
$e->index(
index => 'my_app',
type => 'blog_post',
id => 1,
body => {
title => 'Elasticsearch clients',
content => 'Interesting content...',
date => '2013-09-24'
}
)->then( sub { my $result = shift; do_something($result) } );
# Get the document:
my $doc;
$e->get(
index => 'my_app',
type => 'blog_post',
id => 1
)->then( sub { $doc = shift });
# Search:
my $results;
$e->search(
index => 'my_app',
body => {
query => {
match => { title => 'elasticsearch' }
}
}
)->then( sub { $results = shift });
# Cluster requests:
$e->cluster->info ->then( sub { do_something(@_) });
$e->cluster->health ->then( sub { do_something(@_) });
$e->cluster->node_stats->then( sub { do_something(@_) });
# Index requests:
$e->indices->create(index=>'my_index')->then( sub { do_something(@_) });
$e->indices->delete(index=>'my_index')->then( sub { do_something(@_) });
DESCRIPTION
Search::Elasticsearch::Async is the official asynchronous Perl client
for Elasticsearch, supported by elastic.co <
http://elastic.co>.
Elasticsearch itself is a flexible and powerful open source, distributed
real-time search and analytics engine for the cloud. You can read more
about it on elastic.co <
http://www.elastic.co>.
This module uses Promises to provide a sane async interface, making your
async code look more like synchronous code. It can be used with
Mojolicious or with any of the event loops supported by AnyEvent.
Search::Elasticsearch::Async builds on Search::Elasticsearch, which you
should see for the main documentation.
PREVIOUS VERSIONS OF ELASTICSEARCH
This version of the async client supports the Elasticsearch 5.0 branch,
which is not backwards compatible with earlier branches.
If you need to talk to a version of Elasticsearch before 5.0.0, please
install one of the following packages:
* Search::Elasticsearch::Client::2_0::Async
* Search::Elasticsearch::Client::1_0::Async
* Search::Elasticsearch::Client::0_90::Async
USING PROMISES
First, go and read Promises::Cookbook::GentleIntro, which tells you
everything you need to know about working with Promises. Using them with
Search::Elasticsearch::Async is easy:
Choose a Promises backend
The Promises module does not use an event loop by default. You need to
specify the one to use at the start of your application. Typically, you
will be using the EV event loop (which both AnyEvent and Mojo prefer),
in which case you need:
use Promises backend => ['EV'];
Otherwise you can specify the "Mojo" or "AnyEvent" backends.
Instantiate the client
use Search::Elasticsearch::Async;
my $es = Search::Elasticsearch::Async->new( %params );
See "CREATING A NEW INSTANCE" for an explantion of %params.
Make a request
my $promise = $es->search;
All requests to Elasticsearch return a Promise object, which is a value
that will be resolved later on. You can call "then()" on the $promise to
specify a success callback and an error callback:
$promise->then(
sub { my $result = shift; do_something() }, # success callback
sub { my $error = shift; warn $error } # error callback
);
So far, so much like "CONDITION VARIABLES" in AnyEvent... but "then()"
returns another $promise, which makes them chainable:
$promise->then(sub { print "Got a result"; return @_ })
->then(sub { my $result = shift; something_async($result) })
->then(sub { my $next_result = shift; ...etc...})
->catch(sub { warn "Something failed: @_"});
See Promises::Cookbook::GentleIntro for a full explanation of what you
can do with Promises.
Start the event loop
Async requests are run by the event loop, so no promises will be
resolved or rejected until the event loop is started. In a fully async
application, you would start the event loop once and just let it run
until the application exits. For instance, here's a simple example which
reads search keywords from STDIN, performs an async search and prints
the results. This process is repeated until the application is
interrupted with "Ctrl-C".:
use v5.12;
use AnyEvent;
use Search::Elasticsearch::Async;
# EV must be installed
use Promises (backend => ['EV'], 'deferred');
my $es = Search::Elasticsearch::Async->new;
main();
say "Starting";
# start the event loop
EV::run;
sub main {
read_input()
->then( \&do_search )
->then( \&print_results )
# warn if either of the above steps throws an error
->catch( sub { warn "Something went wrong: @_"; } )
# regardless of success or failure, run main() again
->finally( \&main );
}
sub read_input {
say "Enter search keywords:";
# We wrap AnyEvent so that it returns a promise
# which is resolved when we have read from STDIN
my $d = deferred;
my $w;
$w = AnyEvent->io(
fh => \*STDIN,
poll => 'r',
cb => sub {
chomp( my $input = <STDIN> );
undef $w;
# resolve the promise
$d->resolve($input);
}
);
# return a promise
return $d->promise;
}
sub do_search {
my $keywords = shift();
# returns a promise
$es->search(
index => 'myindex',
body => {
query => {
match => {
title => $keywords
}
}
}
);
}
sub print_results {
my $results = shift;
my $total = $results->{hits}{total};
unless ($total) {
say "No results found";
return;
}
say "$total results found";
my $i = 1;
for ( @{ $results->{hits}{hits} } ) {
say $i++ . ': ' . $_->{_source}{title};
}
}
CREATING A NEW INSTANCE
The "new()" method returns a new client which can be used to run
requests against the Elasticsearch cluster.
use Search::Elasticsearch::Async;
my $e = Search::Elasticsearch::Async->new( %params );
The most important arguments to "new()" are the following:
"nodes"
The "nodes" parameter tells the client which Elasticsearch nodes it
should talk to. It can be a single node, multiples nodes or, if not
specified, will default to "localhost:9200":
# default: localhost:9200
$e = Search::Elasticsearch::Async->new();
# single
$e = Search::Elasticsearch::Async->new( nodes => 'search_1:9200');
# multiple
$e = Search::Elasticsearch::Async->new(
nodes => [
'search_1:9200',
'search_2:9200'
]
);
Each "node" can be a URL including a scheme, host, port, path and
userinfo (for authentication). For instance, this would be a valid node:
https://username:
[email protected]:443/prefix/path
See "node" in Search::Elasticsearch::Role::Cxn for more on node
specification.
"cxn_pool"
The CxnPool modules manage connections to nodes in the Elasticsearch
cluster. They handle the load balancing between nodes and failover when
nodes fail. Which "CxnPool" you should use depends on where your cluster
is. There are three choices:
* "Async::Static"
$e = Search::Elasticsearch::Async->new(
cxn_pool => 'Async::Static' # default
nodes => [
'search1.domain.com:9200',
'search2.domain.com:9200'
],
);
The Async::Static connection pool, which is the default, should be
used when you don't have direct access to the Elasticsearch cluster,
eg when you are accessing the cluster through a proxy. See
Search::Elasticsearch::CxnPool::Async::Static for more.
* "Async::Sniff"
$e = Search::Elasticsearch::Async->new(
cxn_pool => 'Async::Sniff',
nodes => [
'search1:9200',
'search2:9200'
],
);
The Async::Sniff connection pool should be used when you do have
direct access to the Elasticsearch cluster, eg when your web servers
and Elasticsearch servers are on the same network. The nodes that
you specify are used to *discover* the cluster, which is then
*sniffed* to find the current list of live nodes that the cluster
knows about. See Search::Elasticsearch::CxnPool::Async::Sniff.
* "Async::Static::NoPing"
$e = Search::Elasticsearch::Async->new(
cxn_pool => 'Async::Static::NoPing'
nodes => [
'proxy1.domain.com:80',
'proxy2.domain.com:80'
],
);
The Async::Static::NoPing connection pool should be used when your
access to a remote cluster is so limited that you cannot ping
individual nodes with a "HEAD /" request.
See Search::Elasticsearch::CxnPool::Async::Static::NoPing for more.
"trace_to"
For debugging purposes, it is useful to be able to dump the actual HTTP
requests which are sent to the cluster, and the response that is
received. This can be enabled with the "trace_to" parameter, as follows:
# To STDERR
$e = Search::Elasticsearch::Async->new(
trace_to => 'Stderr'
);
# To a file
$e = Search::Elasticsearch::Async->new(
trace_to => ['File','/path/to/filename']
);
Logging is handled by Log::Any. See
Search::Elasticsearch::Logger::LogAny for more information.
Other
Other arguments are explained in the respective module docs.
RUNNING REQUESTS
When you create a new instance of Search::Elasticsearch::Async, it
returns a client object, which can be used for running requests.
use Search::Elasticsearch::Async;
my $e = Search::Elasticsearch::Async->new( %params );
# create an index
$e->indices->create( index => 'my_index' )
->then(sub {
# index a document
$e->index(
index => 'my_index',
type => 'blog_post',
id => 1,
body => {
title => 'Elasticsearch clients',
content => 'Interesting content...',
date => '2013-09-24'
}
);
});
See Search::Elasticsearch::Client::6_0::Direct for more details about
the requests that can be run.
MODULES
Each chunk of functionality is handled by a different module, which can
be specified in the call to new() as shown in cxn_pool above. For
instance, the following will use the
Search::Elasticsearch::CxnPool::Async::Sniff module for the connection
pool.
$e = Search::Elasticsearch::Async->new(
cxn_pool => 'Async::Sniff'
);
Custom modules can be named with the appropriate prefix, eg
"Search::Elasticsearch::CxnPool::", or by prefixing the full class name
with "+":
$e = Search::Elasticsearch::Async->new(
cxn_pool => '+My::Custom::CxnClass'
);
The modules that you can override are specified with the following
arguments to "new()":
"client"
The class to use for the client functionality, which provides methods
that can be called to execute requests, such as "search()", "index()" or
"delete()". The client parses the user's requests and passes them to the
"transport" class to be executed.
The default version of the client is "6_0::Direct", which can be
explicitly specified as follows:
$e = Search::Elasticsearch::Async->new(
client => '6_0::Direct'
);
See :
* Search::Elasticsearch::Client::6_0::Direct (default, for 6.0 branch)
* Search::Elasticsearch::Client::5_0::Direct (for 5.0 branch)
* Search::Elasticsearch::Client::2_0::Direct (for 2.0 branch)
* Search::Elasticsearch::Client::1_0::Direct (for 1.0 branch)
* Search::Elasticsearch::Client::0_90::Direct (for 0.90 branch)
"transport"
The Transport class accepts a parsed request from the "client" class,
fetches a "cxn" from its "cxn_pool" and tries to execute the request,
retrying after failure where appropriate. See:
* Search::Elasticsearch::Async::Transport
"cxn"
The class which handles raw requests to Elasticsearch nodes. See:
* Search::Elasticsearch::Cxn::AEHTTP (default)
* Search::Elasticsearch::Cxn::Mojo
"cxn_factory"
The class which the "cxn_pool" uses to create new "cxn" objects. See:
* Search::Elasticsearch::Cxn::Factory
"cxn_pool" (2)
The class to use for the connection pool functionality. It calls the
"cxn_factory" class to create new "cxn" objects when appropriate. See:
* Search::Elasticsearch::CxnPool::Async::Static (default)
* Search::Elasticsearch::CxnPool::Async::Sniff
* Search::Elasticsearch::CxnPool::Async::Static::NoPing
"logger"
The class to use for logging events and tracing HTTP requests/responses.
See:
* Search::Elasticsearch::Logger::LogAny
"serializer"
The class to use for serializing request bodies and deserializing
response bodies. See:
* Search::Elasticsearch::Serializer::JSON (default)
* Search::Elasticsearch::Serializer::JSON::Cpanel
* Search::Elasticsearch::Serializer::JSON::XS
* Search::Elasticsearch::Serializer::JSON::PP
HELPER MODULES
Search::Elasticsearch::Client::6_0::Async::Bulk and
Search::Elasticsearch::Client::6_0::Async::Scroll are helper modules
which assist with bulk indexing and scrolled searching, eg:
$es->scroll_helper(
index => 'myindex',
on_result => sub { my $doc = shift; do_something($doc) }
)->then( sub { say "Done!" });
BUGS
This is a stable API but this implementation is new. Watch this space
for new releases.
If you have any suggestions for improvements, or find any bugs, please
report them to
<
http://github.com/elasticsearch/elasticsearch-perl/issues>. I will be
notified, and then you'll automatically be notified of progress on your
bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Search::Elasticsearch::Async
You can also look for information at:
* GitHub
<
http://github.com/elasticsearch/elasticsearch-perl>
* CPAN Ratings
<
http://cpanratings.perl.org/d/Search::Elasticsearch::Async>
* Search MetaCPAN
<
https://metacpan.org/module/Search::Elasticsearch::Async>
* IRC
The #elasticsearch <irc://irc.freenode.net/elasticsearch> channel on
"irc.freenode.net".
* Mailing list
The main Elasticsearch mailing list <
http://discuss.elastic.co>.
TEST SUITE
The full test suite requires a live Elasticsearch node to run, and
should be run as :
perl Makefile.PL
ES=localhost:9200 make test
TESTS RUN IN THIS WAY ARE DESTRUCTIVE! DO NOT RUN AGAINST A CLUSTER WITH
DATA YOU WANT TO KEEP!
AUTHOR
Enrico Zimuel <
[email protected]>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2021 by Elasticsearch BV.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004
