POE::Filter::ReferenceUser Contributed Perl DocumentaPOE::Filter::Reference(3)NAMEPOE::Filter::Reference - freeze and thaw arbitrary Perl data
SYNOPSIS
#!perl
use YAML;
use POE qw(Wheel::ReadWrite Filter::Reference);
POE::Session->create(
inline_states => {
_start => sub {
pipe(my($read, $write)) or die $!;
$_[HEAP]{io} = POE::Wheel::ReadWrite->new(
InputHandle => $read,
OutputHandle => $write,
Filter => POE::Filter::Reference->new(),
InputEvent => "got_perl_data",
);
$_[HEAP]{io}->put(
{ key_1 => 111, key_2 => 222 }
);
},
got_perl_data => sub {
print "Got data:\n", YAML::Dump($_[ARG0]);
print "Bye!\n";
delete $_[HEAP]{io};
}
}
);
POE::Kernel->run();
exit;
DESCRIPTIONPOE::Filter::Reference allows programs to send and receive arbitrary
Perl data structures without worrying about a line protocol. Its put()
method serializes Perl data into a byte stream suitable for
transmission. get_one() parses the data structures back out of such a
stream.
By default, POE::Filter::Reference uses Storable to do its magic. A
different serializer may be specified at construction time.
PUBLIC FILTER METHODSPOE::Filter::Reference deviates from the standard POE::Filter API in
the following ways.
new [SERIALIZER [, COMPRESSION]]
new() creates and initializes a POE::Filter::Reference object. It will
use Storable as its default SERIALIZER if none other is specified.
If COMPRESSION is true, Compress::Zlib will be called upon to reduce
the size of serialized data. It will also decompress the incoming
stream data.
Any class that supports nfreeze() (or freeze()) and thaw() may be used
as a SERIALIZER. If a SERIALIZER implements both nfreeze() and
freeze(), then the "network" version will be used.
SERIALIZER may be a class name:
# Use Storable explicitly, specified by package name.
my $filter = POE::Filter::Reference->new("Storable");
# Use YAML instead. Compress its output, as it may be verbose.
my $filter = POE::Filter::Reference->new("YAML", 1);
SERIALIZER may also be an object:
# Use an object.
my $serializer = Data::Serializer::Something->new();
my $filter = POE::Filter::Reference->new($serializer);
If SERIALIZER is omitted or undef, the Reference filter will try to use
Storable, FreezeThaw, and YAML in that order. POE::Filter::Reference
will die if it cannot find one of these serializers, but this rarely
happens now that Storable and YAML are bundled with Perl.
# A choose-your-own-serializer adventure!
# We'll still deal with compressed data, however.
my $filter = POE::Filter::Reference->new(undef, 1);
POE::Filter::Reference will try to compress frozen strings and
uncompress them before thawing if COMPRESSION is true. It uses
Compress::Zlib for this. POE::Filter::Reference doesn't need
Compress::Zlib if COMPRESSION is false.
new() will try to load any classes it needs.
SERIALIZER API
Here's what POE::Filter::Reference expects of its serializers.
thaw SERIALIZED
thaw() is required. It accepts two parameters: $self and a scalar
containing a SERIALIZED byte stream representing a single Perl data
structure. It returns a reconstituted Perl data structure.
sub thaw {
my ($self, $stream) = @_;
my $reference = $self->_deserialization_magic($stream);
return $reference;
}
nfreeze REFERENCE
Either nfreeze() or freeze() is required. They behave identically,
except that nfreeze() is guaranteed to be portable across networks and
between machine architectures.
These freezers accept two parameters: $self and a REFERENCE to Perl
data. They return a serialized version of the REFERENCEd data.
sub nfreeze {
my ($self, $reference) = @_;
my $stream = $self->_serialization_magic($reference);
return $stream;
}
freeze REFERENCE
freeze() is an alternative form of nfreeze(). It has the same call
signature as nfreeze(), but it doesn't guarantee that serialized data
will be portable across machine architectures.
If you must choose between implementing freeze() and nfreeze() for use
with POE::Filter::Reference, go with nfreeze().
SEE ALSO
Please see POE::Filter for documentation regarding the base interface.
The SEE ALSO section in POE contains a table of contents covering the
entire POE distribution.
BUGS
Not so much bugs as caveats:
It's important to use identical serializers on each end of a
connection. Even different versions of the same serializer can break
data in transit.
Most (if not all) serializers will re-bless data at the destination,
but many of them will not load the necessary classes to make their
blessings work.
AUTHORS & COPYRIGHTS
The Reference filter was contributed by Artur Bergman, with changes by
Philip Gwyn.
Please see POE for more information about authors and contributors.
perl v5.14.2 2011-12-15 POE::Filter::Reference(3)
