Net::UDP(3) User Contributed Perl Documentation Net::UDP(3)NAMENet::UDP - UDP sockets interface module
SYNOPSIS
use Net::Gen; # optional
use Net::Inet; # optional
use Net::UDP;
DESCRIPTION
The "Net::UDP" module provides services for UDP communications over
sockets. It is layered atop the "Net::Inet" and "Net::Gen" modules,
which are part of the same distribution.
Public Methods
The following methods are provided by the "Net::UDP" module itself,
rather than just being inherited from "Net::Inet" or "Net::Gen".
new Usage:
$obj = new Net::UDP;
$obj = new Net::UDP $desthost, $destservice;
$obj = new Net::UDP \%parameters;
$obj = new Net::UDP $desthost, $destservice, \%parameters;
$obj = 'Net::UDP'->new();
$obj = 'Net::UDP'->new($desthost);
$obj = 'Net::UDP'->new($desthost, $destservice);
$obj = 'Net::UDP'->new(\%parameters);
$obj = 'Net::UDP'->new($desthost, $destservice, \%parameters);
Returns a newly-initialised object of the given class. If called
for a derived class, no validation of the supplied parameters will
be performed. (This is so that the derived class can add the
parameter validation it needs to the object before allowing the
validation.) Otherwise, it will cause the parameters to be vali-
dated by calling its "init" method, which "Net::UDP" inherits from
"Net::Inet". In particular, this means that if both a host and a
service are given, that an object will only be returned if a con-
nect() call was successful.
The examples above show the indirect object syntax which many pre-
fer, as well as the guaranteed-to-be-safe static method call.
There are occasional problems with the indirect object syntax,
which tend to be rather obscure when encountered. See
http://www.xray.mpe.mpg.de/mail-
ing-lists/perl5-porters/1998-01/msg01674.html for details.
PRINT
Usage:
$ok = $obj->PRINT(@args);
$ok = print $tied_fh @args;
This method, intended to be used with tied filehandles, behaves
like one of two inherited methods from the "Net::Gen" class,
depending on the setting of the object parameter "unbuffered_out-
put". If that parameter is false (the default), then the normal
print() builtin is used. If the "unbuffered_output" parameter is
true, then each print() operation will actually result in a call to
the "send" method, requiring that the object be connected or that
its message is in response to its last normal recv() (with a
"flags" parameter of 0). The value of the $\ variable is ignored
in that case, but the $, variable is still used if the @args array
has multiple elements.
READLINE
Usage:
$line_or_datagram = $obj->READLINE;
$line_or_datagram = <TIED_FH>;
$line_or_datagram = readline(TIED_FH);
@lines_or_datagrams = $obj->READLINE;
@lines_or_datagrams = <TIED_FH>;
@lines_or_datagrams = readline(TIED_FH);
This method, intended to be used with tied filehandles, behaves
like one of two inherited methods from the "Net::Gen" class,
depending on the setting of the object parameter
"unbuffered_input". If that parameter is false (the default), then
this method does line-buffering of its input as defined by the cur-
rent setting of the $/ variable. If the <unbuffered_input> parame-
ter is true, then the input records will be exact recv() datagrams,
disregarding the setting of the $/ variable. Note that invoking
the "READLINE" method in list context is likely to hang, since UDP
sockets typically don't return EOF.
Protected Methods
none.
Known Socket Options
There are no object parameters registered by the "Net::UDP" module
itself.
Known Object Parameters
The following object parameters are registered by the "Net::UDP" module
(as distinct from being inherited from "Net::Gen" or "Net::Inet"):
unbuffered_input
If true, the "READLINE" operation on tied filehandles will return
each recv() buffer as though it were a single separate line, inde-
pendently of the setting of the $/ variable. The default is false,
which causes the "READLINE" interface to return lines split at
boundaries as appropriate for $/. (The "READLINE" method for tied
filehandles is the "<FH>" operation.) Note that calling the "READ-
LINE" method in list context is likely to hang for UDP sockets.
unbuffered_output
If true, the "PRINT" operation on tied filehandles will result in
calls to the send() builtin rather than the print() builtin, as
described in "PRINT" above. The default is false, which causes the
"PRINT" method to use the print() builtin.
unbuffered_IO
This object parameter's value is unreliable on "getparam" or "get-
params" method calls. It is provided as a handy way to set both
the "unbuffered_output" and "unbuffered_input" object parameters to
the same value at the same time during "new" calls.
TIESCALAR support
Tieing of scalars to a UDP handle is supported by inheritance from the
"TIESCALAR" method of "Net::Gen". That method only succeeds if a call
to a "new" method results in an object for which the "isconnected"
method returns true, which is why it is mentioned in regard to this
module.
Example:
tie $x,'Net::UDP',0,'daytime' or die "tie to Net::UDP: $!";
$x = "\n"; $x = "\n";
print $y if defined($y = $x);
untie $x;
This is an expensive re-implementation of "date" on many machines.
Each assignment to the tied scalar is really a call to the "put" method
(via the "STORE" method), and each read from the tied scalar is really
a call to the "READLINE" method (via the "FETCH" method).
TIEHANDLE support
As inherited from "Net::Inet" and "Net::Gen", with the addition of
unbuffered I/O options for the "READLINE" and "PRINT" methods.
Example:
tie *FH,'Net::UDP',{unbuffered_IO => 1, thisport => $n, thishost => 0}
or die;
while (<FH>) {
last if is_shutdown_msg($_);
print FH response($_);
}
untie *FH;
This shows how to make a UDP-based filehandle return (and send) data-
grams even when used in the usual perlish paradigm. For some applica-
tions, this can be helpful to avoid cluttering the message processing
code with the details of handling datagrams. In particular, this exam-
ple relies on the underlying support for replying to the last address
in a recvfrom() for datagram sockets, thus hiding the details of track-
ing and using that information.
Exports
none
THREADING STATUS
This module has been tested with threaded perls, and should be as
thread-safe as perl itself. (As of 5.005_03 and 5.005_57, that's not
all that safe just yet.) It also works with interpreter-based threads
('ithreads') in more recent perl releases.
SEE ALSONet::Inet(3), Net::Gen(3)AUTHOR
Spider Boardman <spidb@cpan.org>
perl v5.8.8 2007-10-29 Net::UDP(3)
