'\"
'\" Generated from file 'bee\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2004 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>
'\"
.TH "bee" n 0\&.1 tcllib "BitTorrent"
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.SH "STANDARD OPTIONS"
.LP
.nf
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See the \\*(So manual entry for details on the standard options.
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Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
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.BS
.SH NAME
bee \- BitTorrent Serialization Format Encoder/Decoder
.SH SYNOPSIS
package require \fBTcl  8\&.4\fR
.sp
package require \fBbee  ?0\&.1?\fR
.sp
\fB::bee::encodeString\fR \fIstring\fR
.sp
\fB::bee::encodeNumber\fR \fIinteger\fR
.sp
\fB::bee::encodeListArgs\fR \fIvalue\fR\&.\&.\&.
.sp
\fB::bee::encodeList\fR \fIlist\fR
.sp
\fB::bee::encodeDictArgs\fR \fIkey\fR \fIvalue\fR\&.\&.\&.
.sp
\fB::bee::encodeDict\fR \fIdict\fR
.sp
\fB::bee::decode\fR \fIstring\fR ?\fIendvar\fR? ?\fIstart\fR?
.sp
\fB::bee::decodeIndices\fR \fIstring\fR ?\fIendvar\fR? ?\fIstart\fR?
.sp
\fB::bee::decodeChannel\fR \fIchan\fR \fB-command\fR \fIcmdprefix\fR ?\fB-exact\fR? ?\fB-prefix\fR \fIdata\fR?
.sp
\fBcmdprefix\fR \fBeof\fR \fItoken\fR
.sp
\fBcmdprefix\fR \fBerror\fR \fItoken\fR \fImessage\fR
.sp
\fBcmdprefix\fR \fBvalue\fR \fItoken\fR \fIvalue\fR
.sp
\fB::bee::decodeCancel\fR \fItoken\fR
.sp
\fB::bee::decodePush\fR \fItoken\fR \fIstring\fR
.sp
.BE
.SH DESCRIPTION
.PP
The \fBbee\fR package provides de- and encoder commands for data
in bencoding (speak 'bee'), the serialization format for data and
messages used by the BitTorrent protocol\&.
.PP
.SH "PUBLIC API"
.SS ENCODER
The package provides one encoder command for each of the basic forms,
and two commands per container, one taking a proper tcl data structure
to encode in the container, the other taking the same information as
several arguments\&.
.PP
.TP
\fB::bee::encodeString\fR \fIstring\fR
Returns the bee-encoding of the \fIstring\fR\&.
.TP
\fB::bee::encodeNumber\fR \fIinteger\fR
Returns the bee-encoding of the \fIinteger\fR number\&.
.TP
\fB::bee::encodeListArgs\fR \fIvalue\fR\&.\&.\&.
Takes zero or more bee-encoded values and returns the bee-encoding of
their list\&.
.TP
\fB::bee::encodeList\fR \fIlist\fR
Takes a list of bee-encoded values and returns the bee-encoding of the
list\&.
.TP
\fB::bee::encodeDictArgs\fR \fIkey\fR \fIvalue\fR\&.\&.\&.
Takes zero or more pairs of keys and values and returns the
bee-encoding of the dictionary they form\&. The values are expected to
be already bee-encoded, but the keys must not be\&. Their encoding will
be done by the command itself\&.
.TP
\fB::bee::encodeDict\fR \fIdict\fR
Takes a dictionary list of string keys and bee-encoded values and
returns the bee-encoding of the list\&. Note that the keys in the input
must not be bee-encoded already\&. This will be done by the command
itself\&.
.PP
.PP
.SS DECODER
The package provides two main decoder commands, one for decoding a
string expected to contain a complete data structure, the other for
the incremental decoding of bee-values arriving on a channel\&. The
latter command is asynchronous and provides the completed decoded
values to the user through a command callback\&.
.PP
.TP
\fB::bee::decode\fR \fIstring\fR ?\fIendvar\fR? ?\fIstart\fR?
Takes the bee-encoding in the string and returns one decoded value\&. In
the case of this being a container all contained values are decoded
recursively as well and the result is a properly nested tcl list
and/or dictionary\&.
.sp
If the optional \fIendvar\fR is set then it is the name of a variable
to store the index of the first character \fIafter\fR the decoded
value into\&. In other words, if the string contains more than one value
then \fIendvar\fR can be used to obtain the position of the bee-value
after the bee-value currently decoded\&. together with \fIstart\fR, see
below, it is possible to iterate over the string to extract all
contained values\&.
.sp
The optional \fIstart\fR index defaults to \fB0\fR, i\&.e\&. the
beginning of the string\&. It is the index of the first character of the
bee-encoded value to extract\&.
.TP
\fB::bee::decodeIndices\fR \fIstring\fR ?\fIendvar\fR? ?\fIstart\fR?
Takes the same arguments as \fB::bee::decode\fR and returns the same
information in \fIendvar\fR\&. The result however is different\&. Instead
of the tcl value contained in the \fIstring\fR it returns a list
describing the value with respect to type and location (indices for
the first and last character of the bee-value)\&. In case of a container
the structure also contains the same information for all the embedded
values\&.
.sp
Formally the results for the various types of bee-values are:
.RS
.TP
string
A list containing three elements:
.RS
.IP \(bu
The constant string \fBstring\fR, denoting the type of the value\&.
.IP \(bu
An integer number greater than or equal to zero\&. This is the index of
the first character of the bee-value in the input \fIstring\fR\&.
.IP \(bu
An integer number greater than or equal to zero\&. This is the index of
the last character of the bee-value in the input \fIstring\fR\&.
.RE
.sp
\fINote\fR that this information is present in the results for all
four types of bee-values, with only the first element changing
according to the type of the value\&.
.TP
integer
The result is like for strings, except that the type element contains
the constant string \fBinteger\fR\&.
.TP
list
The result is like before, with two exceptions: One, the type element
contains the constant string \fBlist\fR\&. And two, the result
actually contains four elements\&. The last element is new, and contains
the index data as described here for all elements of the bee-list\&.
.TP
dictionary
The result is like for strings, except that the type element contains
the constant string \fBdict\fR\&. A fourth element is present as well,
with a slightly different structure than for lists\&. The element is a
dictionary mapping from the strings keys of the bee-dictionary to a
list containing two elements\&. The first of them is the index
information for the key, and the second element is the index
information for the value the key maps to\&. This structure is the only
which contains not only index data, but actual values from the
bee-string\&. While the index information of the keys is unique enough,
i\&.e\&. serviceable as keys, they are not easy to navigate when trying to
find particular element\&. Using the actual keys makes this much easier\&.
.RE
.sp
.TP
\fB::bee::decodeChannel\fR \fIchan\fR \fB-command\fR \fIcmdprefix\fR ?\fB-exact\fR? ?\fB-prefix\fR \fIdata\fR?
The command creates a decoder for a series of bee-values arriving on
the channel \fIchan\fR and returns its handle\&. This handle can be used
to remove the decoder again\&.
Setting up another bee decoder on \fIchan\fR while a bee decoder is
still active will fail with an error message\&.
.sp
.RS
.TP
\fB-command\fR
The command prefix \fIcmdprefix\fR specified by the \fIrequired\fR
option \fB-command\fR is used to report extracted values and
exceptional situations (error, and EOF on the channel)\&.
The callback will be executed at the global level of the interpreter,
with two or three arguments\&. The exact call signatures are
.sp
.RS
.TP
\fBcmdprefix\fR \fBeof\fR \fItoken\fR
The decoder has reached eof on the channel \fIchan\fR\&. No further
invocations of the callback will be made after this\&. The channel has
already been closed at the time of the call, and the \fItoken\fR is
not valid anymore as well\&.
.TP
\fBcmdprefix\fR \fBerror\fR \fItoken\fR \fImessage\fR
The decoder encountered an error, which is not eof\&. For example a
malformed bee-value\&. The \fImessage\fR provides details about the
error\&. The decoder token is in the same state as for eof,
i\&.e\&. invalid\&. The channel however is kept open\&.
.TP
\fBcmdprefix\fR \fBvalue\fR \fItoken\fR \fIvalue\fR
The decoder received and successfully decoded a bee-value\&.
The format of the equivalent tcl \fIvalue\fR is the same as returned
by \fB::bee::decode\fR\&. The channel is still open and the decoder
token is valid\&. This means that the callback is able to remove the
decoder\&.
.RE
.sp
.TP
\fB-exact\fR
By default the decoder assumes that the remainder of the data in the
channel consists only of bee-values, and reads as much as possible per
event, without regard for boundaries between bee-values\&. This means
that if the the input contains non-bee data after a series of
bee-value the beginning of that data may be lost because it was
already read by the decoder, but not processed\&.
.sp
The \fB-exact\fR was made for this situation\&. When specified the
decoder will take care to not read any characters behind the currently
processed bee-value, so that any non-bee data is kept in the channel
for further processing after removal of the decoder\&.
.sp
.TP
\fB-prefix\fR
If this option is specified its value is assumed to be the beginning
of the bee-value and used to initialize the internal decoder
buffer\&. This feature is required if the creator of the decoder used
data from the channel to determine if it should create the decoder or
not\&. Without the option this data would be lost to the decoding\&.
.RE
.sp
.TP
\fB::bee::decodeCancel\fR \fItoken\fR
This command cancels the decoder set up by \fB::bee::decodeChannel\fR
and represented by the handle \fItoken\fR\&.
.TP
\fB::bee::decodePush\fR \fItoken\fR \fIstring\fR
This command appends the \fIstring\fR to the internal decoder
buffer\&. It is the runtime equivalent of the option \fB-prefix\fR of
\fB::bee::decodeChannel\fR\&. Use it to push data back into the decoder
when the \fBvalue\fR callback used data from the channel to
determine if it should decode another bee-value or not\&.
.PP
.PP
.SH "FORMAT DEFINITION"
Data in the bee serialization format is constructed from two basic
forms, and two container forms\&. The basic forms are strings and
integer numbers, and the containers are lists and dictionaries\&.
.PP
.TP
String \fIS\fR
A string \fIS\fR of length \fIL\fR is encoded by the string
"\fIL\fR\fB:\fR\fIS\fR", where the length is written out in textual
form\&.
.TP
Integer \fIN\fR
An integer number \fIN\fR is encoded by the string
"\fBi\fR\fIN\fR\fBe\fR"\&.
.TP
List \fIv1\fR \&.\&.\&. \fIvn\fR
A list of the values \fIv1\fR to \fIvn\fR is encoded by the string
"\fBl\fR\fIBV1\fR\&.\&.\&.\fIBVn\fR\fBe\fR"
where "BV\fBi\fR" is the bee-encoding of the value "v\fBi\fR"\&.
.TP
Dict \fIk1\fR -> \fIv1\fR \&.\&.\&.
A dictionary mapping the string key \fIk\fR\fBi\fR to the value
\fIv\fR\fBi\fR, for \fBi\fR in \fB1\fR \&.\&.\&. \fBn\fR
is encoded by the string
"\fBd\fR\fIBK\fR\fBi\fR\fIBV\fR\fBi\fR\&.\&.\&.\fBe\fR"
for i in \fB1\fR \&.\&.\&. \fBn\fR, where "BK\fBi\fR" is the bee-encoding
of the key string "k\fBi\fR"\&.  and "BV\fBi\fR" is the bee-encoding of
the value "v\fBi\fR"\&.
.sp
\fINote\fR: The bee-encoding does not retain the order of the keys in
the input, but stores in a sorted order\&. The sorting is done for the
"raw strings"\&.
.PP
.PP
Note that the type of each encoded item can be determined immediately
from the first character of its representation:
.PP
.TP
i
Integer\&.
.TP
l
List\&.
.TP
d
Dictionary\&.
.TP
[0-9]
String\&.
.PP
.PP
By wrapping an integer number into \fBi\fR\&.\&.\&.\fBe\fR the format
makes sure that they are different from strings, which all begin with
a digit\&.
.SH EXAMPLES
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIbee\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH KEYWORDS
BitTorrent, bee, bittorrent, serialization, torrent
.SH CATEGORY
Networking
.SH COPYRIGHT
.nf
Copyright (c) 2004 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>

.fi
