2 Bit::MorseSignals - The MorseSignals protocol.
8 use Bit::MorseSignals::Emitter;
9 use Bit::MorseSignals::Receiver;
11 my $deuce = new Bit::MorseSignals::Emitter;
12 my $pants = new Bit::MorseSignals::Receiver done => sub { print $_[1], "\n" };
14 $deuce->post('HLAGH') for 1 .. 3;
15 $pants->push while defined ($_ = $deuce->pop);
18 In unidirectionnal communication channels (such as networking or IPC),
19 the main issue is often to know the length of the message. Some possible
20 solutions are fixed-length messages (which is quite cumbersome) or a
21 special ending sequence (but it no longer can appear in the data). This
22 module proposes another solution, by using a begin/end signature
23 specialized for each message.
25 An actual implementation is also provided :
27 Bit::MorseSignals::Emitter is a base class for emitters ;
28 Bit::MorseSignals::Receiver is a base class for receivers ;
30 Go to those pages if you just want the stuff done and don't care about
34 Each byte of the data string is converted into its bits sequence, with
35 bits of lowest weight coming first. All those bits sequences are put
36 into the same order as the characters occur in the string.
38 The header is composed of three bits (lowest weight coming first) :
40 - The 2 first ones denote the data type : a value of 0 is used for a
41 plain string, 1 for an UTF-8 encoded string, and 2 for a Storable
42 object. See also the "CONSTANTS" section ;
43 - The third one is reserved. For compatibility reasons, the receiver
44 should for now enforce the message data type to plain when this bit is
47 The emitter computes then the longuest sequence of successives 0 (say,
48 m) and 1 (n) in the concatenation of the header and the data. A
49 signature is then chosen :
51 - If m > n, we take n+1 times 1 followed by one 0 ;
52 - Otherwise, we take m+1 times 0 followed by one 1.
54 The signal is then formed by concatenating the signature, the header,
55 the data bits and the reversed signature (i.e. the bits of the signature
56 in the reverse order).
58 a ... a b | t0 t1 r | ... data ... | b a ... a
59 signature | header | data | reversed signature
61 The receiver knows that the signature has been sent when it has catched
62 at least one 0 and one 1. The signal is completely transferred when it
63 has received for the first time the whole reversed signature.
67 Default for non-references messages. Try to guess if the given scalar is
68 an UTF-8 string with "Encode::is_utf8".
71 Treats the data as a plain string. No extra mangling in done.
74 Treats the data as an UTF-8 string. The string is
75 "Encode::encode_utf8"'d in a binary string before sending, and
76 "Encode::decode_utf8"'d by the receiver.
79 The scalar, array or hash reference given is "Storable::freeze"'d by the
80 sender and "Storable::thaw"'d by the receiver.
83 The constants "BM_DATA_AUTO", "BM_DATA_PLAIN", "BM_DATA_UTF8" and
84 "BM_DATA_STORABLE" are only exported on request, either by specifying
85 their names or the ':consts' tag.
88 Carp (standard since perl 5), Encode (since perl 5.007003), Storable
92 Bit::MorseSignals::Emitter, Bit::MorseSignals::Receiver.
95 Vincent Pit, "<perl at profvince.com>", <http://www.profvince.com>.
97 You can contact me by mail or on #perl @ FreeNode (vincent or
101 Please report any bugs or feature requests to "bug-bit-morsesignals at
102 rt.cpan.org", or through the web interface at
103 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Bit-MorseSignals>. I
104 will be notified, and then you'll automatically be notified of progress
105 on your bug as I make changes.
108 You can find documentation for this module with the perldoc command.
110 perldoc Bit::MorseSignals
113 Copyright 2008 Vincent Pit, all rights reserved.
115 This program is free software; you can redistribute it and/or modify it
116 under the same terms as Perl itself.