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Author image Felipe Gasper
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NAME

Net::WebSocket::Parser - Parse WebSocket from a filehandle

SYNOPSIS

    my $iof = IO::Framed->new($fh);

    my $parse = Net::WebSocket::Parser->new($iof);

    #See below for error responses
    my $frame = $parse->get_next_frame();

$iof should normally be an instance of IO::Framed::Read. You’re free to pass in anything with a read() method, but that method must implement the same behavior as IO::Framed::Read::read().

METHODS

OBJ->get_next_frame()

A call to this method yields one of the following:

  • If a frame can be read, it will be returned.

  • If we hit an empty read (i.e., indicative of end-of-file), empty string is returned.

  • If only a partial frame is ready, undef is returned.

I/O DETAILS

IO::Framed was born out of work on this module; see that module’s documentation for the particulars of working with it. In particular, note the exceptions IO::Framed::X::EmptyRead and IO::Framed::X::ReadError.

Again, you can use an equivalent interface for frame chunking if you wish.

CONCERNING EMPTY READS

An empty read is how we detect that a file handle (or socket, etc.) has no more data to read. Generally we shouldn’t get this in WebSocket since it means that a peer endpoint has gone away without sending a close frame. It is thus recommended that applications regard an empty read on a WebSocket stream as an error condition; e.g., if you’re using IO::Framed::Read, you should NOT enable the allow_empty_read() behavior.

Nevertheless, this module (and Net::WebSocket::Endpoint) do work when that flag is enabled.

CUSTOM FRAMES SUPPORT

To support reception of custom frame types you’ll probably want to subclass this module and define a specific custom constant for each supported opcode, e.g.:

    package My::WebSocket::Parser;

    use parent qw( Net::WebSocket::Parser );

    use constant OPCODE_CLASS_3 => 'My::WebSocket::Frame::booya';

… where My::WebSocket::Frame::booya is itself a subclass of Net::WebSocket::Base::DataFrame.

You can also use this to override the default classes for built-in frame types; e.g., OPCODE_CLASS_10() will override Net::WebSocket::Frame::pong as the class will be used for pong frames that this module receives. That could be useful, e.g., for compression extensions, where you might want the get_payload() method to decompress so that that detail is abstracted away.