sectokia has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

I am using AnyEvent::HTTPD / AnyEvent::HTTP::Request. I want to be able to do async IO when a request comes in, and have ability to set the response status, and response content-type, based on the result of that async IO.

However I cannot figure out any way to do this. All the examples I have see all require the content-type specified up-front - and their behavior is that the client is immediately sent response headers (with 200 status and content-type), and then async IO callback is provided, such that only the response body can be asynchronously generated. Example based on AnyEvent::HTTPD::Request doc:

$req->respond ({ content => ['text/plain', sub {
   my ($data_cb) = @_;
   # 200 / text/plain already sent to client by now...
 
   # do async io that eventually calls the call back...
   myPromise()->then(sub{
      $data_cb->("OK"); # Too late to change content-type or status co
+de here..
      $data_cb->();
   })->catch(sub{
      $data_cb->("Failed"); # Or here...
      $data_cb->();
   });
 
} });

[download]

Any ideas? Or should I change to a different 'framework'? Thanks!

Replies are listed 'Best First'.
Re: AnyEvent::HTTPD::Request Dynamic Async Response
by Corion (Patriarch) on Jun 06, 2022 at 06:23 UTC

    You can respond even later, as the code in delayed_2_example shows:

    
$httpd->reg_cb (
   '/test' => sub {
      my ($httpd, $req) = @_;

      $t = AnyEvent->timer (after => 2, cb => sub {
         my $txt = "CPU info:\n\n" . `cat /proc/cpuinfo`;
         $req->respond ([200, "ok", { 'Content-Type' => 'text/plain' }
+, $txt]);
      });
   },
);

    [download]

    So you can't "respond" until you have a meaningful content type, but that's OK as you can delay your response.

[reply]
[d/l]
      Duh, Not sure why I thought you couldn't do that... Thanks.
[reply]

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