DOS program MARKER.UUE

Dan Davison Davison at UH.EDU
Sat Nov 16 23:08:02 EST 1991


This note concerns bitnet->internet or internet-> bitnet corruption of
uuencoced files from EMBL and the UH Gene-Server. If you have ever had
a problem with a received file, please check this out. Otherwise,
unless you want to know some gory details of how the inter-network
mail handling systems work, you should skip this message :-)



Foteos Macrides said:
> >       So why couldn't I decode it until after I did an E3 -> 5E
> > global search and replace?  Note that carats are not corrupted
> > when crossing a gateway in the BITNET -> Internet direction, or
> > when travelling entirely down a BITNET chain or entirely via
> > Internet from EMBL, only when going across from Internet to
> > BITNET. 

I bet the Internet->BITNET corruption is gateway dependent. That's one
reason the Gene-Server deposits its bits directly onto BITNET courtesy
of some serious magic here at the UH central mail machine.

Note that the substitution had to be NON-SYMMETRIC; the idea of the
table at the top of each UUENCODE'd file is that any change that
happens to the table also happens to the file, allowing the EBD (EBCDIC
Brain Damage, (tm) by me) to be corrected.

Therefore a global replace of E3->5E would NOT work if the same was
not done to the table at the top of the file (immediately before the
"begin fooo.exe" line).

> Your server is on the Internet 

Umm, kinda. See above. It's transported via SMTP in ASCII to the UH
mail gateway which sits on both the Internet and BITNET. From there it
is transported by the most direct route unless the user specified
something else, like foo at bar.bitnet@cunyvm.cuny.edu, which forwards it
to CUNY for delivery to BITNET.  That's my current understanding,
anyway. 

> so it should also get UUENCODEd files from EMBL without corruption.

Yes, this has been checked repeatedly.

> Rainer exchanged the "historic" file with Rob via 
> Internet, and it was posted to software/BIO-SOFT via genbank.bio.net, so no
> corruption would be expected to that point.  Internet nodes which SHOULD have
> experienced a corruption are those subscribed to BIO+SOFT via
> LISTSERV at IRLEARN.BITNET, because the posting had to cross from Internet to
> BITNET (at STANFORD or CUNY) going from genbank.bio.net to the LISTERVer.  Is
> that so, and could subscribers on such nodes decode the file without doing an
> E3 -> 5E global search and replace?


Ah, you're close to something here. Someone somewhere in this latter
chain is doing a double EBCDIC-ASCII conversion, maybe. One gateway
does the 1966 version, another the later.  But that still doesn't
explain how the *table* got changed differently from the *body* of the
uuencoded file.

>         I also just tried getting an EMBL .UUE file via Email from your
> gene-server, and the carats were not corrupted, but you're using
> PMDF to put it locally onto a BITNET chain (i.e., it didn't cross an
> external Internet -> BITNET gateway getting TO your server from
> EMBL, and it similarly didn't cross one to get here FROM your
> server), so that didn't turn out to be a test of the hypothesis

But you have nicely figured out why the Gene-Server talks to the
BITNET so well...

> (it's the EBCDIC/ASCII mapping at the external gateways that 
> appears to have a bug, which has existed for so long that it's accepted as a
> "characteristic" of the gateways).

I just said that. Oh. You said it first, I should read the whole
message, sorry.

Now, Fote, Rob, Rainer, Don, Dave, any ideas of how to test this
electronically? I could get a disk from Fote with the suspect files, I
suppose. I would really like to track this down.

dan



-- 
dr. dan davison/dept. of biochemical and biophysical sciences/univ. of
Houston/4800 Calhoun/Houston,TX 77204-5934/davison at uh.edu/DAVISON at UHOU

"If the choice had to be made between saving the lives of lawyers or saving
whales, there is little doubt that the overwhelming majority of Americans 
would come down on the side of the whales" Justice Wallach, NY Times 4/3/91

Disclaimer: As always, I speak only for myself, and, usually, only to
myself.





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