yEnc - Developers information

The author is a programmer - not a webdesigner or documentation specialist !

Frequent programming problem (28.03.2003)

I was contacted more than a dozen time by developers who are having problems with the decoding or encoding. They all had the same problem: They did not realize that the NNTP-protocol requires to double a dot in the first colum when a line is sent - and to detect a double dot (and remove one of them) when receiving a line.
So if you are directly posting to or reading from a socket (internet conenction socket), then dont forget this, please.

Other programming problems (28.03.2003)

I have been notified that 'some mailers' are automatically converting the string: 'From' at the start of a line within the body into: '>From'
Especially *nix mailers which keep their mailbox in traditional Unix-style 'mbox-format' without Content-length seem to do it.
(Notification came from Yakov Lerner. Thank you!)

I have been notified that someone had problems with his [NSString characterAtIndex] function when he tried to read yEncoded messages for decoding purposes. That function did characters conversion based on a default local character set. Instead 'raw message data' should have been accessed.
Please keep in mind: No matter what charset your newsreader (or a message-header) specifies: yEncoded data is ALWAYS raw data. Dont use any conversion during encoding or decoding.

Newsgroup for test-posts in yEncoded format (14.Nov.2001)

A newsgroup has been created especially for test-posts in yEncoded format: alt.binaries.test.yenc

This newsgroup is monitored and test-posts are checked for correctness.
An autoposter will send daily short examples for developers.

Mailing list for developers

The mailing list is out of order. There have been no significant changes and discussions since the version 1.3 of the yEnc draft.
Feel free to ask by eMail

Discussion about yEnc is done 'in public' in the newsgroup:

yEncode and MIME

As some people would prefer to include a new encoding into the MIME structure a short discussion was made in comp.mail.mime. Unfortunately it is very difficult to introduce new transfer encodings and also the rest of MIME is pretty difficult (for non MIME specialists) this topic has been moved downwards on the priority list. A short example for a single binary and a multipart binary has been created and is available in the 'Documents' section. Treat it with CARE !

There is a general approach if you want to embed a yEncoded message into MIME:
Take the entire yEncoded message as one block and add all you need for embedding in front of it - and behind it. The =ybegin line with all parameters, the data and the =yend line should stay one block. Even if information is redundant - the =y lines should stay as they are specified (even for multiparts). This allows other decoders to detect such blocks - and decode them properly - even if all other information is stripped from your messages.

14. Jan. 2002: The link to the MIME embedding has been removed. We will try to create a better embedding actually.

Documents, samples and references

Proposed new documents (05.Mar.2002)

These docs are not final - but published to replace at least the original draft 1.0 which might be misunderstandable and/or misleading.

Original documents

Changes: 10. June.2002:

Spelling: "grammer" --> "grammar", "Might" --> "May"

There is no copyright for the yEncoding - it is completely released into public domain.
May it be helpful the Usenet community!

Jürgen Helbing - 10. June 2002 - Email: