AnyEvent recursive blocking wait with Plack

[Dirk Koopman]

On 08/03/12 14:02, Marc Lehmann wrote:
>>> Well, if the Anyevent::HTTPD handler is the only one allowing that then
>>> you are in trouble. If it's a standard feature supported everywehre,
>>> then enjoy - if it's not documented well, you could always ask the Plack
>>> author.
>>
>> Why not use one of the many Plack (http://plackperl.org) compatible
>> frameworks such as: Mojolicious (http://mojolicious.org) or Dancer
>> (http://perldancer.org)? Both of these frameworks (for instance)
>> allow web apps to query other web servers.
>
> Isn't that exactly what he is using? He tried to use AnyEvent::HTTPD,
> which to me looks as plack-compatible as the frameworks you mentioned, and
> also allow web apps to query other web servers.
>

I shouldn't bite - really...

> Do I miss something obvious?
>

Don't use AnyEvent::HTTPD or Plack....

 From the Mojolicious::CookBook (lots of good ideas):

Event loops

Internally the Mojo::IOLoop reactor can use multiple event loop 
backends, EV for example will be automatically used if installed. Which 
in turn allows AnyEvent to just work.

   use Mojolicious::Lite;
   use EV;
   use AnyEvent;

   # Wait 3 seconds before rendering a response
   get '/' => sub {
     my $self = shift;
     my $w;
     $w = AE::timer 3, 0, sub {
       $self->render(text => 'Delayed by 3 seconds!');
       undef $w;
     };
   };

   app->start;

Who actually controls the event loop backend is not important.

   use Mojo::UserAgent;
   use EV;
   use AnyEvent;

   # Search Twitter for "perl"
   my $cv = AE::cv;
   my $ua = Mojo::UserAgent->new;
   $ua->get('http://search.twitter.com/search.json?q=perl' => sub {
     my ($ua, $tx) = @_;
     $cv->send($tx->res->json->{results}->[0]->{text});
   });
   say $cv->recv;

You could for example just embed the built-in web server into an 
AnyEvent application.

   use Mojolicious::Lite;
   use Mojo::Server::Daemon;
   use EV;
   use AnyEvent;

   # Normal action
   get '/' => {text => 'Hello World!'};

   # Connect application with web server and start accepting connections
   my $daemon =
     Mojo::Server::Daemon->new(app => app, listen => ['http://*:8080']);
   $daemon->start;

   # Let AnyEvent take control
   AE::cv->recv;

Helpful?

For what it is worth, I have only used Mojo on some toy apps. I am just 
about to do something a bit more interesting by building a Mojo / 
AnyEvent web app to directly control a (Davis Vantage Pro II) weather 
station (via its serial port), outputting decent HTML5 / 
websocket->javascript style output. None of the native weather programs 
out there are very good. They all seem to have been written 15 years 
ago, or in a style that is that old, and there seem to be no decent perl 
web based solutions.

Dirk