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.\" ========================================================================
.\"
.IX Title "IO::Async::Protocol::Stream 3pm"
.TH IO::Async::Protocol::Stream 3pm 2024-02-04 "perl v5.38.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
"IO::Async::Protocol::Stream" \- base class for stream\-based protocols
.SH SYNOPSIS
.IX Header "SYNOPSIS"
Most likely this class will be subclassed to implement a particular network
protocol.
.PP
.Vb 1
\&   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/^(.*)\en//;
\&      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 $name\en" );
\&   }
.Ve
.PP
This small example elides such details as error handling, which a real
protocol implementation would be likely to contain.
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This subclass of IO::Async::Protocol is intended to stand as a base class
for implementing stream-based protocols. It provides an interface similar to
IO::Async::Stream, primarily, a \f(CW\*(C`write\*(C'\fR method and an \f(CW\*(C`on_read\*(C'\fR event
handler.
.PP
It contains an instance of an IO::Async::Stream object which it uses for
actual communication, rather than being a subclass of it, allowing a level of
independence from the actual stream being used. For example, the stream may
actually be an IO::Async::SSLStream to allow the protocol to be used over
SSL.
.PP
As with IO::Async::Stream, it is required that by the time the protocol
object is added to a Loop, that it either has an \f(CW\*(C`on_read\*(C'\fR method, or has
been configured with an \f(CW\*(C`on_read\*(C'\fR callback handler.
.SH EVENTS
.IX Header "EVENTS"
The following events are invoked, either using subclass methods or CODE
references in parameters:
.ie n .SS "$ret = on_read \e$buffer, $eof"
.el .SS "\f(CW$ret\fP = on_read \e$buffer, \f(CW$eof\fP"
.IX Subsection "$ret = on_read $buffer, $eof"
.SS on_read_eof
.IX Subsection "on_read_eof"
.SS on_write_eof
.IX Subsection "on_write_eof"
The event handlers are invoked identically to IO::Async::Stream.
.SS on_closed
.IX Subsection "on_closed"
The \f(CW\*(C`on_closed\*(C'\fR handler is optional, but if provided, will be invoked after
the stream is closed by either side (either because the \f(CWclose()\fR method has
been invoked on it, or on an incoming EOF).
.SH PARAMETERS
.IX Header "PARAMETERS"
The following named parameters may be passed to \f(CW\*(C`new\*(C'\fR or \f(CW\*(C`configure\*(C'\fR:
.SS "on_read => CODE"
.IX Subsection "on_read => CODE"
.SS "on_read_eof => CODE"
.IX Subsection "on_read_eof => CODE"
.SS "on_write_eof => CODE"
.IX Subsection "on_write_eof => CODE"
CODE references for the events.
.SS "handle => IO"
.IX Subsection "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
\&\f(CW\*(C`transport\*(C'\fR object, a new IO::Async::Stream object will be built around
the given IO handle, and used as the transport.
.SH METHODS
.IX Header "METHODS"
.SS write
.IX Subsection "write"
.Vb 1
\&   $protocol\->write( $data );
.Ve
.PP
Writes the given data by calling the \f(CW\*(C`write\*(C'\fR method on the contained
transport stream.
.SS connect
.IX Subsection "connect"
.Vb 1
\&   $protocol\->connect( %args );
.Ve
.PP
Sets up a connection to a peer, and configures the underlying \f(CW\*(C`transport\*(C'\fR for
the Protocol. Calls IO::Async::Protocol \f(CW\*(C`connect\*(C'\fR with \f(CW\*(C`socktype\*(C'\fR set to
\&\f(CW"stream"\fR.
.SH AUTHOR
.IX Header "AUTHOR"
Paul Evans <leonerd@leonerd.org.uk>