I've been using event loops, but I haven't been able to get the loop to triage to my sub when there are no other events. I've only been able to force my sub to run as a periodic event. Here is the code I have now, but it doesn't actually read any frames. Maybe the subscription isn't being sent correctly? It shows the logic I am trying to accomplish, though.

#!/usr/bin/perl
use strict;
use IO::Socket::SSL;
use IO::Framed;
use Net::WebSocket::Frame::text;
use Net::WebSocket::Parser;
use Net::WebSocket::Endpoint::Client;
use Net::WebSocket::Handshake::Client ();
use Net::WebSocket::HTTP_R ();
use HTTP::Response;
use JSON::XS;
use Data::Dumper;

my @prods = qw(BTC-USD LTC-USD ETH-USD);
my $host = 'ws-feed.gdax.com';
my $wssurl = "wss://$host/";
my $port = 443;

my $inet = IO::Socket::SSL->new("$host:$port")
    or die "failed connect or ssl handshake: $!\n$SSL_ERROR";
$inet->blocking(0);
my $handshake = Net::WebSocket::Handshake::Client->new(
    uri => $wssurl
);
print "REQ HEADERS:\n".$handshake->to_string()."\n";
syswrite $inet, $handshake->to_string() or die $!;
my $buffer = '';
my $cnt = 0;
my $line = <$inet>;
while($line ne "\r\n") {
    $buffer.= $line;
    $line = <$inet>;
}
print "RESP HEADERS:\n$buffer\n";
my $resp = HTTP::Response->parse($buffer);
Net::WebSocket::HTTP_R::handshake_consume_response( $handshake, $resp 
+);

#See below about IO::Framed
my $iof_r = IO::Framed->new($inet);
$iof_r->allow_empty_read();
my $parser = Net::WebSocket::Parser->new( $iof_r );
my $iof_w = IO::Framed->new($inet);
my $ept = Net::WebSocket::Endpoint::Client->new(
    parser => $parser,
    out => $iof_w,
);

my $subscribe = {
    type => 'subscribe',
    product_ids => \@prods,
    channels => ['full']
};
my $payload = encode_json($subscribe);
print $payload."\n";
$iof_w->write(
    Net::WebSocket::Frame::text->new( payload => $payload )
);

while(1) {
    while(1) {
        # we are catching up
        print "get next frame\n";
        my $frame = $ept->get_next_message();
        print "\$frame = \"$frame\"\n";
        last unless($frame);
        load_frame(decode_json($frame));
    }
    # we are caught up
    somethinghard();
    # catch up again
}

sub somethinghard {
    print "something hard\n";
    sleep 1;
}

sub load_frame {
    my ($frame) = @_;
    my $data = decode_json($frame);
    print Dumper($data);
}
[download]