[INN] #106: XBATCH documentation

INN rra at stanford.edu
Sat Dec 27 11:08:08 UTC 2008


#106: XBATCH documentation
-------------------------+--------------------------------------------------
 Reporter:  iulius       |        Owner:  eagle
     Type:  enhancement  |       Status:  new  
 Priority:  low          |    Milestone:       
Component:  doc          |      Version:       
 Severity:  wishlist     |   Resolution:       
 Keywords:  compliance   |  
-------------------------+--------------------------------------------------
Changes (by iulius):

  * component:  innd => doc


Comment:

 According to Russ Allbery in an [http://lists.eyrie.org/pipermail/ietf-
 nntp/2008-September/006017.html IETF-NNTP posting]:

 Compressed feeds in general require something that replaces the current
 data conveyance method so that you can convey arbitrary binary data over
 NNTP.  The problem with the existing NNTP protocol for binary data is that
 the data MUST end in CRLF, which is considered part of the data.  We need
 some way of avoiding that, or some set of commands that say that the first
 CRLF of CRLF.CRLF isn't part of the data.

 XBATCH is worth documenting.  I don't know if it's worth standardizing as
 BATCH, but I wouldn't mind at all.  Most of the work there will be
 defining the batch format, and that will depend on how many different
 transforms people feel like writing up (c7unbatch, cunbatch, gunbatch,
 etc.).

 In practice, there are five interesting batch formats: straight rnews, the
 binary compressed formats for compress, gzip, and bzip2 (cunbatch,
 gunbatch, and bunbatch respectively), and c7unbatch, which is cunbatch
 with a transport encoding that I'm not sure anything else uses

     The encoding uses characters from 0x20 (' ') through 0x7A ('z').
 (That fits nicely into the UUCP 'f' protocol by Piet Beertema.)  First,
 expand three eight-bit charcters into four six-bit ones.  Collect until we
 have 13, and spread the last one over the first 12, so that we have 12
 6.5-bit characters.  Since there are very few half-bit machines, collect
 them into pairs, making six 13-bit characters.  We can do this as A * 91 +
 B where A and B are less then 91 after we add 0x20 to make it printable.

 All of them except c7unbatch are fairly easy to document.  c7unbatch we
 might be able to get away with just declaring obsolete.

-- 
Ticket URL: <http://inn.eyrie.org/trac/ticket/106#comment:1>
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