Paul Evans > IO-Async > IO::Async::Protocol::Stream



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IO::Async::Protocol::Stream - base class for stream-based protocols


Most likely this class will be subclassed to implement a particular network protocol.

 package Net::Async::HelloWorld;

 use strict;
 use warnings;
 use base qw( IO::Async::Protocol::Stream );

 sub on_read
    my $self = shift;
    my ( $buffref, $eof ) = @_;

    return 0 unless $$buffref =~ s/^(.*)\n//;
    my $line = $1;

    if( $line =~ m/^HELLO (.*)/ ) {
       my $name = $1;

       $self->invoke_event( on_hello => $name );

    return 1;

 sub send_hello
    my $self = shift;
    my ( $name ) = @_;

    $self->write( "HELLO $name\n" );

This small example elides such details as error handling, which a real protocol implementation would be likely to contain.


This subclass of IO::Async::Protocol is intended to stand as a base class for implementing stream-based protocols. It provides an interface similar to IO::Async::Stream, primarily, a write method and an on_read event handler.

It contains an instance of an IO::Async::Stream object which it uses for actual communication, rather than being a subclass of it, allowing a level of independence from the actual stream being used. For example, the stream may actually be an IO::Async::SSLStream to allow the protocol to be used over SSL.

As with IO::Async::Stream, it is required that by the time the protocol object is added to a Loop, that it either has an on_read method, or has been configured with an on_read callback handler.


The following events are invoked, either using subclass methods or CODE references in parameters:

$ret = on_read \$buffer, $eof



The event handlers are invoked identically to IO::Async::Stream.


The on_closed handler is optional, but if provided, will be invoked after the stream is closed by either side (either because the close() method has been invoked on it, or on an incoming EOF).


The following named parameters may be passed to new or configure:

on_read => CODE

on_read_eof => CODE

on_write_eof => CODE

CODE references for the events.

handle => IO

A shortcut for the common case where the transport only needs to be a plain IO::Async::Stream object. If this argument is provided without a transport object, a new IO::Async::Stream object will be built around the given IO handle, and used as the transport.



   $protocol->write( $data )

Writes the given data by calling the write method on the contained transport stream.


   $protocol->connect( %args )

Sets up a connection to a peer, and configures the underlying transport for the Protocol. Calls IO::Async::Protocol connect with socktype set to "stream".


Paul Evans <>

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