usefor-usepro-02 December 2004

7.4.  Duties of a Serving Agent

   A Serving Agent takes an article from a relaying or injecting agent
   and files it in a "news database". It also provides an interface for
   reading agents to access the news database. This database is normally
   indexed by newsgroup with articles in each newsgroup identified by an
   article-locator (usually in the form of a decimal number - see a-
   6.16).

   A serving agent MUST maintain a list of the newsgroups it stores in
   its news database showing the moderation status of each one (see
   6.2.1), and SHOULD include in that list all groups likely to be
   crossposted to from those groups (e.g. all other groups in the same
   hierarchy(ies)).

        NOTE: Since control messages are often of interest, but should
        not be displayed as normal articles in regular newsgroups, it is
        common for serving agents to make them available in a pseudo-
        newsgroup named "control" or in a pseudo-newsgroup in a sub-
        hierarchy under "control." (e.g. "control.cancel").

   A serving agent MAY decline to accept an article if the Path-content
   contains some path-identity whose articles the serving agent does not
   want, as a matter of local policy.

        NOTE: This last facility is sometimes used to detect and decline
        control messages (notably cancel messages) which have been
        deliberately seeded with a path-identity to be "aliased out" by
        sites not wishing to act upon them.
[INN at least does this. It might be argued that it is not necessary to
mention it here.]

   A serving agent processes articles as follows:

   1. It MUST establish the trusted identity of the source of the
      article and modify the Path-header as for a relaying agent (7.3).

   2. It MUST examine the Injection-Date-header (or, if that is absent,
      the Date-header) and reject the article as stale (a-5.7) if that
      predates the earliest articles of which it normally keeps record,
      or if it is more than 24 hours into the future (the margin MAY be
      less than that 24 hours).

   3. It MUST reject any article that does not include all the mandatory
      headers (section a-5), or which contains any header that does not
      have legal contents.

   4. It SHOULD reject any article that has already been sent to it (a
      database of message identifiers of recent articles is usually kept
      and matched against).


   5. It SHOULD reject any article that matches an already received
      cancel message (or an equivalent Supersedes-header) issued by its
      poster or by some other trusted entity.

   6. It MUST reject any article without an Approved-header posted to
      any newsgroup listed as moderated.

   7. It MUST remove any Xref-header (a-6.16) from each article.  It
      then MAY (and usually will) generate a fresh Xref-header.

   8. Finally, it stores the article in its news database.

   Serving agents MUST NOT create new newsgroups simply because an
   unrecognized newsgroup-name occurs in a Newsgroups-header (see a-
   7.2.1 for the correct method of newsgroup creation).

   Serving agents MUST NOT alter, delete or rearrange any part of an
   article in any other way. The list of particular cases given for
   relaying agents (7.3) applies here also.

--- ../usefor-usepro-01/Duties_of_a_Serving_Agent.out          September 2004
+++ ../usefor-usepro-02/Duties_of_a_Serving_Agent.out          December 2004
@@ -19,24 +19,16 @@
         newsgroup named "control" or in a pseudo-newsgroup in a sub-
         hierarchy under "control." (e.g. "control.cancel").
 
-   A serving agent MAY decline to accept an article if its own path-
-   identity is already present in the Path-content or if the Path-
-   content contains some path-identity whose articles the serving agent
-   does not want, as a matter of local policy.
-[That has been changed from a-5.6.1 in previous drafts, where it said "A
-relaying agent MAY decline...". That seemed plain wrong to me. It is
-fine for a relaying agent to ignore articles which have apparently
-already passed through it (and I still say that), but surely it is for
-serving agents to "reject" for policy reasons, and to which the NOTE
-below would apply.  Comments?]
+   A serving agent MAY decline to accept an article if the Path-content
+   contains some path-identity whose articles the serving agent does not
+   want, as a matter of local policy.
 
         NOTE: This last facility is sometimes used to detect and decline
         control messages (notably cancel messages) which have been
         deliberately seeded with a path-identity to be "aliased out" by
         sites not wishing to act upon them.
-[Again, is this "aliasing out" usually detected by the serving agent, or
-does it more usually work because the previous relaying agent will never
-have sent it in the first place?]
+[INN at least does this. It might be argued that it is not necessary to
+mention it here.]
 
    A serving agent processes articles as follows:
 
@@ -49,13 +41,14 @@
       or if it is more than 24 hours into the future (the margin MAY be
       less than that 24 hours).
 
-   3. It MUST reject any article that does not have the correct
-      mandatory headers (section a-5) present, or which contains any
-      header that does not have legal contents.
+   3. It MUST reject any article that does not include all the mandatory
+      headers (section a-5), or which contains any header that does not
+      have legal contents.
 
    4. It SHOULD reject any article that has already been sent to it (a
       database of message identifiers of recent articles is usually kept
       and matched against).
+
 
    5. It SHOULD reject any article that matches an already received
       cancel message (or an equivalent Supersedes-header) issued by its