streaming-psgi.pl

# StreamingPSGI - Everything is streaming, no special cases
my $env = {
  SERVER_NAME         => 'localhost',
  SERVER_PORT         => 80,
  SCRIPT_NAME         => '',
  REQUEST_METHOD      => 'GET',
  HTTP_CONTENT_LENGTH => 12,
  version             => 3,
  url_scheme          => 'http',
  read                => sub {...},
  status              => sub {...},
  write               => sub {...}
};

# Streaming application
my $app = sub {
  my $env = shift;

  # Request body
  my $input = '';
  $env->{read} = sub {
    my $chunk = shift;
    return $input .= $chunk if defined $chunk;

    # Response
    my $output = "echo: $input";
    $env->{status}->(200, 'OK', ['Content-Length' => length($output)]);
    $env->{write}->($output);
  };
};

# Streaming middleware
my $middleware = sub {
  my ($env, $next) = @_;

  # Response body
  my $write = $env->{write};
  $env->{write} = sub {
    my $chunk = shift;
    say "OUTPUT CHUNK: $chunk";
    return $write->($chunk);
  };

  # Forward to next middleware
  $next->();

  # Request body
  my $read = $env->{read};
  $env->{read} = sub {
    my $chunk = shift;
    say "INPUT CHUNK: $chunk";
    return $read->($chunk);
  };
};