[ih] DNS History

[Vint Cerf]

John,

what a wonderfully pithy description - thanks for sharing it and shedding a
bit more light on that period.

vint



On Mon, Mar 8, 2010 at 5:59 PM, John Day <jeanjour at comcast.net> wrote:

> X.500 in essence killed itself.  (Hoyt Kesterson will kill me for saying so
> . . . )
>
> As usual a number of things came together to kill X.500.  For the most
> part, it was outside the rest of the OSI train wreck.  Like most OSI
> application protocols, it tried to do too much with no real approach to
> reasonable subsets.  (We tried to impress this idea on the Europeans from
> the early 80s on but they would have none of it.) The primary problem was
> that the directory wasn't an application protocol in the usual sense in the
> first place.
>
> First of all, a "directory" was suppose to be something that *only* did
> application name to address mapping.  This is how it is defined in the
> Naming and Addressing Part of the OSI Reference Model (7498-3).  (DNS does
> something entirely different.  Initially, DNS translate a string
> representation of an IP address to a bit string representation.  Today, it
> has morphed into something in between that isn't really a clean separation
> of application name and network address and hence not as rich as is needed
> for a complete architecture.   See Shoch and Saltzer.  Grapevine was the
> first attempt to get it right.)
>
> However, X.500 couldn't just do *that* one thing.  They had to make it
> directory for everything.  In essence, X.500 tried to be an 80s concept of
> Google and a directory all rolled into one, when they should really be two
> different things.  In fact, the early drafts had something called a
> descriptive name that was indistinguishable from a query.
>
> X.500 was done at the height of the RPC fad.  *Everything could be done
> with RPC!*  Request/Response is everything.  One of the more foolish ideas
> to sweep through computer science, even then.  (I made more than a few of
> them unhappy when I pointed out their wonderful new idea was nothing more
> than COBOL coroutines.) X.500 was done by the same crew that did X.400 who
> were madly in love with client/server and RPC and none too swift.  They
> would have pages of syntax definitions (in ASN.1) labeled "Formal
> Description of the Protocol."
>
> When you tried to explain to them that there was more to specifying a
> protocol than just the syntax, you would get blank stares.  When you pointed
> out that you needed to specify the *procedures* what to do when a PDU
> arrived, the still looked at you blankly.  I remember a big meeting that
> Jack Veenstra and I had with John White, PARC and the rest of the X.500
> crew. They thought the names of the attributes in X.500 *were* the
> definition.  That was when I pointed out that I could use the letter "Z" as
> a value in every field in their protocol and it would be conformant.  "But
> that is not what we meant!"  But it was what you specified.  ;-)
>
> Their RPC is everything model sort of broke down as well, when they
> realized querying the directory wasn't the only thing that had to be done.
>  There had to be directory updates as well and they would be really bad if
> they had to request changes rather than be notified of them.
>
> It was a classic case of generalizing off a model that was in fact a
> special case.
>
> I was always surprised that it lasted as long as it did.
>
> Take care,
> John
>
>
> At 12:58 -0800 2010/03/08, Richard Bennett wrote:
>
>> X.500 was a much broader-reaching directory service, whereas DNS was a
>> simple name-to-address mapper. Companies such as Novell did their own
>> directory services, and X.500 never took off because of the skullduggery
>> that killed OSI. John Day's Patterns in Network Architecture covers some of
>> the drama.
>>
>> On 3/8/2010 12:31 PM, Craig Partridge wrote:
>>
>>> First, in terms of the RFC system, where are the comments themselves?
>>>>  Were
>>>> they hard-copies that no longer exist, or mailing lists that have been
>>>> tucked away somewhere?  Is there any correspondence left (for DNS
>>>> related
>>>> RFCs) or has it all been lost?
>>>>
>>>>  There was no formal comment system (nor is there now).  But there were
>>> lots
>>> of comments on drafts on various mailing lists.   For DNS issues the
>>> archives of the namedroppers list is probably your best place
>>> (http://psg.com/lists/namedroppers and kudos to Randy Bush for bringing
>>> it
>>> up)
>>>
>>>
>>>  Second, does anyone have or know where to find details about the
>>>> debates/conversations that took place leading up to RFC 1591 and what
>>>> appears to be a "compromise" between generic and ccTLDs?
>>>>
>>>>  RFC 1591 is awfully late -- most key technical issues, as I recall,
>>> were
>>> determined when RFC973 came out.
>>>
>>>
>>>  Third, it is not entirely clear to me exactly why DNS was engineered in
>>>> place of X.500.  It is my understanding at this early point in my
>>>> research
>>>> that OSI standards seemed inevitable at one point, and sources have told
>>>> me
>>>> that DNS was designed to get something out the door quickly (presumably
>>>> something that *wasn't* X.500).  Was X.500 simply based on an old
>>>> paradigm
>>>> (white pages / old telecom) and seen as a bulky and slow alternative?
>>>>  When,
>>>> and with whom, was the actual decision made to ditch X.500 altogether?
>>>>  This
>>>> part of the story goes a long way to explaining why everyone in the
>>>> world
>>>> doesn't have a unique identifier.
>>>>
>>>>  I have my theory on that subject -- I'll send you the relevant paper I
>>> wrote
>>> on the history of email, there's a brief discussion.
>>>
>>> Thanks!
>>>
>>> Craig
>>>
>>>
>> --
>> Richard Bennett
>> Research Fellow
>> Information Technology and Innovation Foundation
>> Washington, DC
>>
>
>
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