Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP

Writing PSGI Middleware using simple hooks

branch: master

Fetching latest commit…

Cannot retrieve the latest commit at this time

README
NAME
    Plack::Middleware::EasyHooks - PSGI Middleware the easy way

SYNOPSIS
      package Plack::Middleware::MyAccessLog;

      use parent qw(Plack::Middleware::EasyHooks);
 
      sub before {
          my ($self, $env) = @_;

          $env->{MyAccessLog} = {
              start_time    => time(),
              response_size => 0,
          };
      }

      sub filter {
          my ($self, $env, $chunk) = @_;

          $env->{MyAccessLog]->{response_size} += length $chunk;

          return $chunk;
      }

      sub finalize {
          my ($self, $env) = shift;

          my $time = time() - $env->{MyAccessLog}->{start_time};
          my $size = $env->{MyAccessLog}->{response_size};

          warn "Request took $time seconds and sent $size bytes";
      }

      1;

    Or as an inline middleware

      use Plack::Builder;

      my $app = ...; 

      builder {
          enable 'Plack::Middleware::EasyHooks', 
              before    => sub { $_[0]->{start_time} = time(); },
              finalize  => sub {
                  my $time = time() - $_[0]->{start};
                  warn "Request took $time seconds";
              };

          $app;
      }

DESCRIPTION
    Plack::Middleware::EasyHooks takes care of the complexities handling
    streaming in PSGI middleware. Just provide hooks to be called before,
    during and after the wrapped PSGI application.

    The hooks are called in the following order (much simplified):

        before();
        $app->();
        after();
    
        filter($_) for @body;
        tail($env);
    
        finalize();

SUPPORTED HOOKS
    The following methods are available for hooking into the request
    handling

    before( $env )
        This method is called before processing the wrapped PSGI
        application. It receives the PSGI $env hash ref as argument.

        The return value is ignored.

    after( $env, $res )
        This method is called when the app starts to respond. It receives
        the PSGI $env and a array ref containing the status code and headers
        as arguments.

        The middleware can override the status code and headers either by
        updating the elements of this array ref or by returning a array ref
        with the new status code and headers.

    filter ( $env, $chunk )
        This method allows you to filter the content of the response. It is
        called on each chunk of the response.

        The return value is passed to the next level. If the return value is
        "undef" proccessing of the request is stopped.

    tail( $env );
        This methods allows you to add some additional content at the end of
        the body.

    finalize( $env )
        This method is called after the request has been processed.

BUGS
    Unless your PSGI server supports cleanup handles, the finalize() method
    might be calles before the final chunk is successfully sent to the
    client.

AUTHOR
    Peter Makholm <peter@makholm.net>

COPYRIGHT AND LICENSE
    Copyright (C) 2012 by Peter Makholm.

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

Something went wrong with that request. Please try again.