POE::Component - phpMan

NAME
    POE::Component - event driven objects or subsystems

SYNOPSIS
    See specific components.

DESCRIPTION
    POE "components" are event-driven modules that generally encapsulate
    mid- to high-level program features. For example,
    POE::Component::Client::DNS performs message-based asynchronous resolver
    lookups. POE::Component::Server::TCP is a basic asynchronous network
    server.

    The POE::Component namespace was started as place for contributors to
    publish their POE-based modules without requiring coordination with the
    main POE distribution. The namespace predates the -X convention,
    otherwise you'd be reading about POEx instead.

    As with many things in Perl, there is more than one way to implement
    component interfaces. Newer components sport OO interfaces, and some
    even use Moose, but older ones are solely message driven.

OBJECT ORIENTED COMPONENTS
    One way to create object-oriented components is to embed a POE::Session
    instance within an object. This is done by creating the session during
    the object's constructor, setting the session's alias to something
    unique, and saving a copy of the alias in the object.

      package Asynchrotron;

      my $alias_index = 0;

      sub new {
        my $class = shift;
        my $self = bless {
          alias => __PACKAGE__ . " " . ++$alias_index;
        }, $class;

        POE::Session->create(
          object_states => [
            $self => {
              _start       => "_poe_start",
              do_something => "_poe_do_something",
            },
          ],
        );
        return $self;
      }

      sub _poe_start {
        $_[KERNEL]->alias_set($_[OBJECT]->{alias});
      }

    The alias allows object methods to pass events into the session without
    having to store something about the session. The POE::Kernel call()
    transfers execution from the caller session's context into the
    component's session.

      sub do_something {
        my $self = shift;
        print "Inside the caller's session right now: @_\n";
        $poe_kernel->call($self->{alias}, "do_something", @_);
      }

      sub _poe_do_something {
        my @args = @_[ARG0..$#_];
        print "Inside the component's session now: @args\n";
        $_[OBJECT]{count}++;
      }

    Both $_[HEAP] and $_[OBJECT] are visible within the component's session.
    $_[HEAP] can be used for ultra-private encapsulation, while $_[OBJECT]
    may be used for data visible by accessors.

      sub get_count {
        my $self = shift;
        return $self->{count}; # $_[OBJECT]{count} above
      }

    Too many sessions may bog down object creation and destruction, so avoid
    creating them for every object.

SEE ALSO
    The SEE ALSO section in POE contains a table of contents covering the
    entire POE distribution.

    POE::Stage is a nascent project to formalize POE components, make
    POE::Kernel more object-oriented, and provide syntactic and semantic
    sugar for many common aspects of POE::Component development. It's also
    easier to type. Please investigate the project. Ideas and *tuits* are
    badly needed to help get the project off the ground.

TO DO
    Document the customary (but not mandatory!) process of creating and
    publishing a component.

AUTHORS & COPYRIGHTS
    Each component is written and copyrighted separately.

    Please see POE for more information about authors and contributors.