Magma Specs

From Gnufu

This Document in Plain-Text-Format: http://gnuticles.gnufu.net/MAGMA-Specsv22.txt

===========================================
MAGnet MAnifest (.magma) Simple List Format
by Arne Babenhauserheide ( arne_bab@web.de - http://draketo.de )
License: GPLv2 or later. 

MAGMA files are a way to transport Magnet-lists and additional 
information 
in a human-readable way. 

(1) Magma files are a line-oriented text format consisting of a header 
line 
followed by any number of comments and topics. 
It is based off YAML and will likely be extended in the future to be 
able to 
contain more information. This is the first draft and specifies how a 
simple 
parser can extract Magnets from a Magma-File. 

(2) Any line in which the first non-whitespace character is '#' is a 
comment 
through to the end of the line. When a '#' appears somewhere in a line, 
that 
line is a comment from the '#' through to the end of the line. For 
example:

# this is a comment

(3) Lines consisting solely of whitespace are ignored. 

(4) A line which begins with "list:" starts a list of topics, which 
continues, 
till another line starts with any character but a whitespace. 
A line starting with a "#" may be ignored for this purpose (We don't 
want a 
thoughtlessly placed comment to break the list too early). 

(5) Any line in that list beginning with " - " (space-hyphen-space) is 
considered the start of a topic. 

(6) A topic continues till any line begins with less than two spaces 
followed by 
any other character. A new topic begins as described in (5). 

(7) If the topic begins with a magnet-link, that magnet-link must be 
sourrounded 
by double-quotes. The magnet must be the first element of the topic, 
which means, it should be in the first or second line. 
Inside these double-quotes any whitespace is ignored. 
Also any 
linebreak which is followed by at least three spaces is ignored. 

(8) A topic may contain any URI and any number of additional objects. 
Programs 
should ignore every line beginning with an object-nominator they don't 
understand. Any line beginning with two spaces and any character but a 
"-" or a 
"#" is considered the beginning of an object. More on objects in (10). 
Any line 
beginning with two spaces and a "#" is a comment inside the topic. 

If the topic contains a magnet URI, the various magnet attributes have 
their 
usual meanings.

Note that this means the following two lines have an identical meaning 
inside a 
magma file -- each specifies a single exact topic:

 - urn:sha1:BLAH
 - "magnet:?xt=urn:sha1:BLAH" 


(9) Any line inside the double quotation beginning with three or more 
whitespaces, where the first non-whitespace character is not a '#', is 
considered a continuation of the previous topic line and should be 
appended with 
no intervening whitespace. For example:

 - "magnet:?xt=urn:sha1:BLAH
   &dn=magnacarta.jpg"

...is equivalent to...

 - "magnet:?xt=urn:sha1:BLAH&dn=magnacarta.jpg"

(10) Additinal file information can be given as objects in the format 
"nominator:information", where the nominator must be preceded by two 
spaces and 
must be in a new line. Any whitespaces directly following the colon can 
be 
ignored (as they will most probable be placed for greater readability). 

For example this would be a topic which named the hash, download name 
and an 
alternate location without the use of a magnet-link. Watch the second 
line being 
indented by two spaces, one more than the "-": 

 - urn:sha1:BLAH
  dn:magnacarta.jpg
  as:http://BLAK

This should be expanded into the following magnet-link to pass it on to 
magnet-
aware programs: 

magnet:?xt=urn:sha1:BLAH&dn=magnacarta.jpg&as=http://BLAK


(11) The first line should begin "#MAGMA" and a Version number. In this 
case 
"#MAGMAv0.2". This can be ignored by simpleminded parsers as a comment, 
but is 
also a hint/"magic number" to help indicate the file's type in 
situations where 
the manifest may have been acquired solely by a typeless urn:sha1: 
(etc.) 
identifier. The rest of the first line must not be used as a regular 
comment. 
(See #12.)

(12) The first line may include an optional "virtual magnet URI" 
describing the 
manifest itself. In such a magnet URI, the 'mt' may be set to '.' to 
mean 
'this'.
For example:

#MAGMAv0.2 magnet:?mt=.&dn=My%20First%20Manifest

This first line cannot make use of the continuation facility described 
in (5).

(13) Another, more extensible Magnet Manifest format will be defined in 
the 
future. The specs for this Version of the Magnet Manifest (0.2) will 
stay 
compatible at least till v0.4 and also after that magnnets should be 
extractable 
from MAGMA-files using the sheme described in here. 

====================================
AN EXAMPLE

You might come across a magnet URI like either of the following:


magnet:?xt=urn:sha1:B4LGBGBX2J7PBNXRCQVS474Y5DW3I6WB
&dn=gnufu-files-v0.2.magma
&xs=http://edrikor.dyndns.org:9845/uri-res/N2R?urn:sha1:

B4LGBGBX2J7PBNXRCQVS474Y5DW3I6WB
&as=http://magnet-uri.sourceforge.net/proposals/arne/gnufu-files.magma

magnet:?mt=http://magnet-uri.sourceforge.net/proposals/arne/gnufu-files.magma

By either finding a file with the exact matching SHA1 (in the first 
case), or by 
fetching the given HTTP URL (in the second case), you might wind up 
with the 
following file:

==== BEGIN EXAMPLE FILE ====
#MAGMAv0.2 
magnet:?mt=.&dn=gnufu-files-v0.2.magma&as=http://magnet-uri.sourceforge.net/proposals/arne/gnufu-files-v0.2.magma

# these are the documents created for GnuFU: Gnutella For Users, 
# a simple guide to Gnutella and recent changes in the Gnutella-network
# written in userfriendly style. 

list: 
 - "magnet:?xt=urn:sha1:7BHEGP445NVQUNSDFHOK5FFC3P65HANG
   &dn=gnufu-en-2004-06-26.rtd.zip
   &xs=http://edrikor.dyndns.org:9845
   /uri-res/N2R?urn:sha1:7BHEGP445NVQUNSDFHOK5FFC3P65HANG"
   
 - "magnet:?xt=urn:sha1:GK6T2LZV2IPAY57XWQTCQLWWGEGPJ6SG
   &dn=gnufu-en-2004-06-26.pdf
   &xs=http://edrikor.dyndns.org:9845
   /uri-res/N2R?urn:sha1:GK6T2LZV2IPAY57XWQTCQLWWGEGPJ6SG"

 - "magnet:?xt=urn:sha1:3QL5VEGHQZWNP34NCLZVSIZF3HK4P5VZ
   &dn=gnufu-de-2004-06-26.rtd.zip
   &xs=http://edrikor.dyndns.org:9845
   /uri-res/N2R?urn:sha1:3QL5VEGHQZWNP34NCLZVSIZF3HK4P5VZ"

 - "magnet:?xt=urn:sha1:2A5ERFKC3EBAUTRQSIYZY5GABB6MYMXF
   &dn=gnufu-de-2004-06-26.pdf
   &xs=http://edrikor.dyndns.org:9845
   /uri-res/N2R?urn:sha1:2A5ERFKC3EBAUTRQSIYZY5GABB6MYMXF"
==== END EXAMPLE FILE ====

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