NAME

    POE::Component::Curl::Multi - a fast HTTP POE component

VERSION

    version 0.16

SYNOPSIS

      use strict;
      use warnings;
      use HTTP::Request::Common qw[GET];
      use POE qw[Component::Curl::Multi];
    
      $!=1;
    
      my @urls = ( 'https://api.github.com/repos/git/git/tags',
                   'http://this.is.made.up.stuff/',
                   'http://www.cpan.org/',
                   'http://www.google.com/', );
    
      my $curl = POE::Component::Curl::Multi->spawn(
        Alias => 'curl',
        FollowRedirects => 5,
        Max_Concurrency => 10,
      );
    
      POE::Session->create(
        package_states => [
          main => [qw(_start _response)],
        ],
      );
    
      $poe_kernel->run();
      exit 0;
    
      sub _start {
        $poe_kernel->post( 'curl', 'request', '_response', GET($_) ) for @urls;
        return;
      }
    
      sub _response {
        my ($request_packet, $response_packet) = @_[ARG0, ARG1];
        use Data::Dumper;
        local $Data::Dumper::Indent=1;
        warn Dumper( $response_packet->[0] );
        return;
      }

DESCRIPTION

    POE::Component::Curl::Multi is an HTTP user-agent for POE. It lets
    other sessions run while HTTP transactions are being processed, and it
    lets several HTTP transactions be processed in parallel.

    It uses Net::Curl internally to provide access to libcurl for fast
    performance. It strives to be API compatible(ish) with
    POE::Component::Client::HTTP.

    It is inspired by AnyEvent::Curl::Multi.

CONSTRUCTOR

    spawn

      Starts an instance of the component. Takes a number of options:

      alias

	Set an alias for this instance of the component. There is no
	default.

      timeout

	Specifies a timeout, in seconds, for each request, defaults to 180.

      followredirects

	Specifies how many redirects (e.g. 302 Moved) to follow. If not
	specified defaults to 0, and thus no redirection is followed.

      agent

	Can either be a string or an ARRAYREF of strings. This will be used
	as UserAgent header in requests. If an ARRAYREF is provided one of
	them will be picked randomly to send.

	See
	http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTUSERAGENT

      proxy

	Specify a proxy to use.

	See
	http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTPROXY

      max_concurrency

	Specify the maximum number of concurrent requests, a value of 0
	means no limit will be imposed. The default is 0.

      curl_debug

	Enable libcurl's verbosity.

	See
	http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTVERBOSE

      Returns an object that accepts some methods as documented below.

 AVAILABLE METHODS

    session_id

      Takes no arguments. Returns the ID of the component's session.

    shutdown

      Responds to all pending requests with 408 (request timeout), and then
      shuts down the component and all subcomponents.

    pending_requests_count

      Returns the number of requests currently being processed.

    cancel

      Cancel a specific HTTP request. Requires a reference to the original
      request (blessed or stringified) so it knows which one to cancel.

ACCEPTED EVENTS

    Sessions communicate asynchronously with the component. They post
    requests to it, and it posts responses back.

 request

    Requests are posted to the component's request state. They include an
    HTTP::Request object which defines the request. For example:

      $kernel->post(
        'ua', 'request',            # http session alias & state
        'response',                 # my state to receive responses
        GET('http://poe.perl.org'), # a simple HTTP request
        'unique id',                # a tag to identify the request
        'progress',                 # an event to indicate progress
        'http://1.2.3.4:80/'        # proxy to use for this request
      );

    This invocation is compatible with POE::Component::Client::HTTP.

    You may also send either an arrayref or hashref to the request state
    with the following parameters:

    request

      A HTTP::Request object which defines the request.

    response

      Either a string specifying the state in the sender session to receive
      responses or, alternatively, a POE::Session postback that will be
      invoked with responses.

    tag

      A tag to identify the request.

    progress

      An optional handler, if specified the component will provide progress
      metrics (see sample handler below).

    proxy

      Specify a proxy to use. This overrides the proxy set with spawn, if
      applicable.

      See http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTPROXY

    session

      Specify a POE::Session object, ID or alias to send responses to
      instead of the sending session. If a postback is used for response,
      this option will be ignored.

 pending_requests_count

    Returns the number of requests currently being processed. To receive
    the return value, it must be invoked with $kernel->call().

      my $count = $kernel->call('ua' => 'pending_requests_count');

    This is also available as a method on the object returned by spawn

      my $count = $curl->pending_requests_count();

 shutdown

    Responds to all pending requests with 408 (request timeout), and then
    shuts down the component and all subcomponents.

SENT EVENTS

 response handler

    In addition to all the usual POE parameters, HTTP responses come with
    two list references:

      my ($request_packet, $response_packet) = @_[ARG0, ARG1];

    $request_packet contains a reference to the original HTTP::Request
    object. This is useful for matching responses back to the requests that
    generated them.

      my $http_request_object = $request_packet->[0];
      my $http_request_tag    = $request_packet->[1]; # from the 'request' post

    $response_packet contains a reference to the resulting HTTP::Response
    object.

      my $http_response_object = $response_packet->[0];

    Please see the HTTP::Request and HTTP::Response manpages for more
    information.

 progress handler

    The example progress handler shows how to calculate a percentage of
    download completion.

      sub progress_handler {
        my $gen_args  = $_[ARG0];    # args passed to all calls
        my $call_args = $_[ARG1];    # args specific to the call
    
        my $req = $gen_args->[0];    # HTTP::Request object being serviced
        my $tag = $gen_args->[1];    # Request ID tag from.
        my $got = $call_args->[0];   # Number of bytes retrieved so far.
        my $tot = $call_args->[1];   # Total bytes to be retrieved.
    
        my $percent = $got / $tot * 100;
    
        printf(
          "-- %.0f%% [%d/%d]: %s\n", $percent, $got, $tot, $req->uri()
        );
    
        return;
      }

STREAMING

    This component does not (yet) support POE::Component::Client::HTTP's
    streaming options.

CLIENT HEADERS

    POE::Component::Curl::Multi sets its own response headers with
    additional information. All of its headers begin with "X-PCCH".

 X-PCCH-Errmsg

    POE::Component::Curl::Multi may fail because of an internal client
    error rather than an HTTP protocol error. X-PCCH-Errmsg will contain a
    human readable reason for client failures, should they occur.

    The text of X-PCCH-Errmsg may also be repeated in the response's
    content.

 X-PCCH-Peer

    This response header is not yet supported.

ATTRIBUTION

    POE::Component::Curl::Multi is based on both

    POE::Component::Client::HTTP by Rocco Caputo, Rob Bloodgood and Martijn
    van Beers

    and

    AnyEvent::Curl::Multi by Michael S. Fischer

SEE ALSO

    Net::Curl

    AnyEvent::Curl::Multi

    POE::Component::Client::HTTP

AUTHOR

    Chris Williams

COPYRIGHT AND LICENSE

    This software is copyright (c) 2020 by Chris Williams, Michael S.
    Fischer, Rocco Caputo, Rob Bloodgood and Martijn van Beers.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.