Subject: #1414: USEPRO 3.2.1: delimiter for multiple Path identities

From: Russ Allbery <[email-masked]>
Date: Sat, 21 Apr 2007 19:33:15 -0700

Harald Tveit Alvestrand <[email-masked]> writes:

> #1414: USEPRO 3.2.1: delimiter for multiple Path identities
>  No discussion
> #1415: USEPRO 3.2.1: Number of path entries per site
>  Discussion, but no proposed text.

Easy one first.  Here is my proposed text for #1414, which also addresses
part of Charles's concerns in #1415.  There hasn't been any subsequent
discussion of my original response to #1414, so I'm going to go with my
preferred option of MUST/SHOULD for "!" vs. "!!".

--- usepro.xml	2007-02-19 22:20:06.000000000 -0800
+++ usepro-1414.xml	2007-04-21 19:31:58.000000000 -0700
@@ -373,16 +373,21 @@
               specification will add only single "!" characters between
               &lt;path-identity> strings.</t>
 
-              <t>The agent MUST then prepend its own &lt;path-identity> to
-              the Path header field content.</t>
-
-              <t>The agent MAY then prepend additional &lt;path-identity>s
-              for itself to the Path header field content, following each
-              &lt;path-identity> so added with either "!!" or "!".  This
-              is permitted for agents that have multiple
-              &lt;path-identity>s (such as during a transition from one to
-              another).  Each of these &lt;path-identity>s MUST meet the
-              requirements set out in <xref target="path" />.</t>
+              <t>The agent MAY then prepend to the Path header field
+              content "!" or "!!" followed by an additional
+              &lt;path-identity> for itself other than its primary one.
+              Using "!!" is RECOMMENDED.  This step may be repeated any
+              number of times.  This is permitted for agents that have
+              multiple &lt;path-identity>s (such as during a transition
+              from one to another).  Each of these &lt;path-identity>s
+              MUST meet the requirements set out in
+              <xref target="path" />.</t>
+
+              <t>Finally, the agent MUST prepend its primary
+              &lt;path-identity> to the Path header field content.  The
+              primary &lt;path-identity> is the &lt;path-identity> it
+              normally advertises to its peers for their use in generating
+              &lt;path-diagnostic>s as described above.</t>
             </list>
           </t>
 
Here's the new text rendered:

   4.  The agent MAY then prepend to the Path header field content "!"
       or "!!" followed by an additional <path-identity> for itself
       other than its primary one.  Using "!!" is RECOMMENDED.  This
       step may be repeated any number of times.  This is permitted for
       agents that have multiple <path-identity>s (such as during a
       transition from one to another).  Each of these <path-identity>s
       MUST meet the requirements set out in Section 3.2.

   5.  Finally, the agent MUST prepend its primary <path-identity> to
       the Path header field content.  The primary <path-identity> is
       the <path-identity> it normally advertises to its peers for their
       use in generating <path-diagnostic>s as described above.

-- 
Russ Allbery ([email-masked])             <http://www.eyrie.org/~eagle/>

---

From: Frank Ellermann <[email-masked]>
Date: Sun, 22 Apr 2007 19:50:27 +0200

Russ Allbery wrote:

>+ Using "!!" is RECOMMENDED.
[...]

Is that new ?  I thought that's already accepted text.

>+ The primary &lt;path-identity> is the &lt;path-identity>
>+ it normally advertises to its peers for their use in
>+ generating &lt;path-diagnostic>s as described above.</t>

Good.  An XML-editor keeping ">" as is only because it's
allowed would make me nervous, but that's off topic... :-)

---

From: Russ Allbery <[email-masked]>
Date: Sun, 22 Apr 2007 12:51:21 -0700

> allowed would make me nervous, but that's off topic... :-)

XML editor?  What's that?  :)  (I'm too anal about indentation and
whitespace and all the XML editors I've used do things subtlely wrong for
me.)

---

From: "Charles Lindsey" <[email-masked]>
Date: Mon, 23 Apr 2007 14:02:45 GMT

>preferred option of MUST/SHOULD for "!" vs. "!!".

OK, so what about #1415? I seem to remember suggesting a revised wording
for the introductory paragraph of 3.2.1 of the form:

   Except possibly when relaying to other hosts on the same site, every
   injecting, relaying, or serving agent that accepts an article MUST
   update the Path header field ....

So if the point is accepted, that wording should still work. See issue
tracker #1415 for full discussion.

>       use in generating <path-diagnostic>s as described above.

Yes that is much better. I would suggest, however

    "... Using "!!" is RECOMMENDED (where the second "!" is intended to be
    interpreted as a <diag-match>, such as might have been added in Step 3
    if that additional <path-identity> has been placed there by a separate
    agent).

IOW, software/humans reading the Path do not need to be aware whether
successive <path-identity>s were added by the same of by different agents.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
Email: [email-masked]      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5

---

From: Russ Allbery <[email-masked]>
Date: Mon, 23 Apr 2007 10:42:01 -0700

Charles Lindsey <[email-masked]> writes:
> Russ Allbery <[email-masked]> writes:

>> Easy one first.  Here is my proposed text for #1414, which also
>> addresses part of Charles's concerns in #1415.  There hasn't been any
>> subsequent discussion of my original response to #1414, so I'm going to
>> go with my preferred option of MUST/SHOULD for "!" vs. "!!".

> tracker #1415 for full discussion.

This part of #1415 I still don't agree with, and I didn't get the feeling
there was a consensus in favor of (see also Richard's comments).  I'm not
horribly *upset* by your proposal either, but so far it seemed like
discussion was running 2 to 1 against.

>     "... Using "!!" is RECOMMENDED (where the second "!" is intended to
>     be interpreted as a <diag-match>, such as might have been added in
>     Step 3 if that additional <path-identity> has been placed there by a
>     separate agent).

I agree that that's the explanation, but it's a big wad of parenthetical
in the middle of the point.  Hm.

How about:

    "... Using "!!", and thereby adding <diag-match> since the
    <path-identity> is verified, is RECOMMENDED."

---

From: Frank Ellermann <[email-masked]>
Date: Tue, 24 Apr 2007 13:47:45 +0200

>     <path-identity> is verified, is RECOMMENDED."

Sure.  I thought the rationale is obvious, but explicitly stating
it in one short sentence is better.

---

From: "Charles Lindsey" <[email-masked]>
Date: Fri, 27 Apr 2007 20:08:17 GMT

>discussion was running 2 to 1 against.

OK, it is down as an Issue, so in due course the WG will have to decide it
one way or the other. The Sky will not Fall In either way. I raised it
because I had understood that is what the WG had originally agreed.

>    "... Using "!!", and thereby adding <diag-match> since the
                                        ^
                                        a
>    <path-identity> is verified, is RECOMMENDED."
                       ^
                  clearly/obviously

Yes, something like that would be fine.

---

From: Russ Allbery <[email-masked]>
Date: Sat, 28 Apr 2007 18:44:31 -0700

> Yes, something like that would be fine.

Here is the modified text proposal (as an XML diff):

--- usepro.xml	2007-02-19 22:20:06.000000000 -0800
+++ usepro-1414.xml	2007-04-28 18:43:12.000000000 -0700
@@ -373,16 +373,22 @@
               specification will add only single "!" characters between
               &lt;path-identity> strings.</t>
 
-              <t>The agent MUST then prepend its own &lt;path-identity> to
-              the Path header field content.</t>
-
-              <t>The agent MAY then prepend additional &lt;path-identity>s
-              for itself to the Path header field content, following each
-              &lt;path-identity> so added with either "!!" or "!".  This
-              is permitted for agents that have multiple
-              &lt;path-identity>s (such as during a transition from one to
-              another).  Each of these &lt;path-identity>s MUST meet the
-              requirements set out in <xref target="path" />.</t>
+              <t>The agent MAY then prepend to the Path header field
+              content "!" or "!!" followed by an additional
+              &lt;path-identity> for itself other than its primary one.
+              Using "!!", and thereby adding a &lt;diag-match> since the
+              &lt;path-identity clearly is verified, is RECOMMENDED.  This
+              step may be repeated any number of times.  This is permitted
+              for agents that have multiple &lt;path-identity>s (such as
+              during a transition from one to another).  Each of these
+              &lt;path-identity>s MUST meet the requirements set out in
+              <xref target="path" />.</t>
+
+              <t>Finally, the agent MUST prepend its primary
+              &lt;path-identity> to the Path header field content.  The
+              primary &lt;path-identity> is the &lt;path-identity> it
+              normally advertises to its peers for their use in generating
+              &lt;path-diagnostic>s as described above.</t>
             </list>
           </t>