John,<div><br></div><div>what a wonderfully pithy description - thanks for sharing it and shedding a bit more light on that period.</div><div><br></div><div>vint</div><div><br></div><div><br><br><div class="gmail_quote">On Mon, Mar 8, 2010 at 5:59 PM, John Day <span dir="ltr"><<a href="mailto:jeanjour@comcast.net">jeanjour@comcast.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">X.500 in essence killed itself. (Hoyt Kesterson will kill me for saying so . . . )<br>
<br>
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.<br>
<br>
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.)<br>
<br>
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.<br>
<br>
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."<br>
<br>
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. ;-)<br>
<br>
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.<br>
<br>
It was a classic case of generalizing off a model that was in fact a special case.<br>
<br>
I was always surprised that it lasted as long as it did.<br>
<br>
Take care,<br><font color="#888888">
John</font><div><div></div><div class="h5"><br>
<br>
At 12:58 -0800 2010/03/08, Richard Bennett wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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.<br>
<br>
On 3/8/2010 12:31 PM, Craig Partridge wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
First, in terms of the RFC system, where are the comments themselves? Were<br>
they hard-copies that no longer exist, or mailing lists that have been<br>
tucked away somewhere? Is there any correspondence left (for DNS related<br>
RFCs) or has it all been lost?<br>
<br>
</blockquote>
There was no formal comment system (nor is there now). But there were lots<br>
of comments on drafts on various mailing lists. For DNS issues the<br>
archives of the namedroppers list is probably your best place<br>
(<a href="http://psg.com/lists/namedroppers" target="_blank">http://psg.com/lists/namedroppers</a> and kudos to Randy Bush for bringing it<br>
up)<br>
<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Second, does anyone have or know where to find details about the<br>
debates/conversations that took place leading up to RFC 1591 and what<br>
appears to be a "compromise" between generic and ccTLDs?<br>
<br>
</blockquote>
RFC 1591 is awfully late -- most key technical issues, as I recall, were<br>
determined when RFC973 came out.<br>
<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Third, it is not entirely clear to me exactly why DNS was engineered in<br>
place of X.500. It is my understanding at this early point in my research<br>
that OSI standards seemed inevitable at one point, and sources have told me<br>
that DNS was designed to get something out the door quickly (presumably<br>
something that *wasn't* X.500). Was X.500 simply based on an old paradigm<br>
(white pages / old telecom) and seen as a bulky and slow alternative? When,<br>
and with whom, was the actual decision made to ditch X.500 altogether? This<br>
part of the story goes a long way to explaining why everyone in the world<br>
doesn't have a unique identifier.<br>
<br>
</blockquote>
I have my theory on that subject -- I'll send you the relevant paper I wrote<br>
on the history of email, there's a brief discussion.<br>
<br>
Thanks!<br>
<br>
Craig<br>
<br>
</blockquote>
<br>
--<br>
Richard Bennett<br>
Research Fellow<br>
Information Technology and Innovation Foundation<br>
Washington, DC<br>
</blockquote>
<br>
</div></div></blockquote></div><br></div>