From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Duncan <1i5t5.duncan@cox.net> Newsgroups: gmane.discuss,gmane.emacs.help Subject: Re: aioe (was: Re: Is there a problem with Gmane at the moment?) Date: Sun, 15 May 2016 22:13:07 +0000 (UTC) Message-ID: References: <864ma15sjs.fsf@student.uu.se> <86y47d4dt3.fsf@student.uu.se> <864ma1fdtf.fsf@student.uu.se> <87r3d5j9oz.fsf@gnus.org> <8660ugtdsj.fsf_-_@student.uu.se> <861t54td7a.fsf@student.uu.se> <86bn47ka9m.fsf@student.uu.se> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1463350433 3639 80.91.229.3 (15 May 2016 22:13:53 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 15 May 2016 22:13:53 +0000 (UTC) Cc: help-gnu-emacs@gnu.org To: gmane-discuss@quimby.gnus.org Original-X-From: gmane-discuss-bounces@hawk.netfonds.no Mon May 16 00:13:43 2016 Return-path: Envelope-to: gd-gmane-discuss@m.gmane.org Original-Received: from quimby.gnus.org ([80.91.231.51]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1b24I6-0008Ep-SK for gd-gmane-discuss@m.gmane.org; Mon, 16 May 2016 00:13:38 +0200 Original-Received: from localhost ([127.0.0.1] helo=quimby.gnus.org) by quimby.gnus.org with esmtp (Exim 4.80) (envelope-from ) id 1b24I6-0003fT-5w; Mon, 16 May 2016 00:13:38 +0200 Original-Received: from plane.gmane.org ([80.91.229.3]) by quimby.gnus.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1b24I5-0003fN-HB for gmane-discuss@quimby.gnus.org; Mon, 16 May 2016 00:13:37 +0200 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1b24Hs-00080m-9S for gmane-discuss@quimby.gnus.org; Mon, 16 May 2016 00:13:24 +0200 Original-Received: from ip98-167-165-199.ph.ph.cox.net ([98.167.165.199]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 16 May 2016 00:13:24 +0200 Original-Received: from 1i5t5.duncan by ip98-167-165-199.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 16 May 2016 00:13:24 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 139 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: ip98-167-165-199.ph.ph.cox.net User-Agent: Pan/0.141 (Tarzan's Death; GIT fefda68dd) X-BeenThere: gmane-discuss@hawk.netfonds.no X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gmane-discuss-bounces@hawk.netfonds.no Original-Sender: "Gmane-discuss" Xref: news.gmane.org gmane.discuss:17061 gmane.emacs.help:109964 Archived-At: Emanuel Berg posted on Sun, 15 May 2016 10:15:01 +0200 as excerpted: > Duncan <1i5t5.duncan@cox.net> writes: > >> This one appeared because it was cross-posted, and the gmane.discuss >> list got it, so it appeared in both. >> >> The others didn't appear as they're (presumably) not cross-posted, at >> least not to an actually working (from gmane?) list. > > Yes, the thought of this explanation "crossed" my mind, but I couldn't > make sense of it! > > If I can't post to A, but to B, and then post to A *and* B, then I can > post to A as well as B! > > The only way I can think of it is that it is some illusion provided by > Gmane so that when it appears I read on A, I actually read on B. But the > illusion apparently works for you as, as well! > > Is that how it works? You have to remember that we're dealing with a news server here, and while news messages look a lot like mail, there's some differences. But of course gmane isn't just a news server, it's actually a (mailing-)list2news gateway, and some things must be fudged a little bit to make one appear as the other. On a normal news server, a cross-posted message normally appears in all groups it was posted to that the news server carries. When a message propagates from one server to another, the headers say what groups it is posted to, and those don't change, regardless of whether the news server actually carries all of them or not, the server simply ignores groups it doesn't carry and puts the message in the groups it does. (If it doesn't carry at least one of them it is of course not interested in the message at all, so the message doesn't propagate to that server.) This way, the message can be propagated from a server only carrying some of the groups, to another carrying all of the groups, and the message will appear in all the groups on the second server, which carries all of them, even tho the first server didn't. This, BTW, is one reason why some news providers entirely drop messages with binary attachments that are cross-posted to non-binaries groups. The message can't appear in the non-binary groups because it's a binary, but it's cross-posted to both binary and non-binary groups that the server carries, so the server simply drops it in the binary groups as well, to avoid it appearing in the non-binary groups. Or at least that was the explanation. A lot of users thought that if they could institute separate binaries and retention policies for the binary groups vs non- binary, they could have gotten around it if they wanted to, but... (Back in the day, supernews was the big provider known for this policy that few others followed. But supernews got bought out by IIRC giganews, and I don't know if supernews is even around as a separate brand these days, and if it is, if it still has that same policy.) So on a normal news server, the message is propagated once to the news server and it can place it in all cross-posted groups it carries based on that single propagation. On gmane, things work rather differently. First, gmane never posts messages as they are posted directly from users. It forwards them via mail to the appropriate mailing list, and only posts the message after it gets it back from the mailing list via gmane's own list subscription. At least, that's the way it works for single-posted messages. Cross-posted messages get more complicated, first because now, gmane has to send the message to multiple lists, separately, if the lists aren't all served by the same listserv, as would be the case here. Each list and listserv then processes the message using its own list policies, and only if the message isn't blocked either by issues with the listserv itself or by list/listserv policies (maybe some lists only take posts from subscribers, or consider the post spam for some reason, and block it), does it get send back to gmane, along with the other list subscribers. Then when gmane gets the post, it has to figure out what to do with it, since it's cross-posted. As it happens, gmane apparently follows the normal news server rules here and after converting the mailing list headers back to news, cross-posts the message to all groups/lists it carries. The critical difference here being, gmane may or may not get the message again from the other lists it was sent to, while a normal news server will only have the message propagated to it once (when multi-peering, a normal news server will reject the message as already seen before propagation, thus reducing transfer volume between the peers), but it's already cross-posted, either way. So gmane basically throws away the cross-posted messages it has already received from other lists, while normal news servers don't ever receive them again in the first place as they already have them, so don't have to throw them away. But the real difference with crossposts for gmane users, as opposed to single-list-posts, is that single lists posts appear if and only if that list is actually working and doesn't block the post, so it gets sent back to the subscribers including gmane, while cross-posts will appear on gmane on all lists/groups as soon as they're sent back to gmane by just one. So if there's a broken listserv, as we apparently have here, the only posts appearing on that list while it or its server is broken will be ones that were cross-posted to some other list, that was /not/ broken at the time. Which is why your cross-post to gmane.discuss appeared almost instantly. Because that list happens to be hosted locally by gmane, and when it accepted and set out the post, it appeared on gmane in the emacs group as well, even tho that server is broken and not returning posts at this time. > What would happen if I cross-posted to A and B as above, only I didn't > subscribe to B? Would it still work on A? And if so, would that qualify > a magic? It depends on the exact mechanism both gmane and your news client use to process cross-posts. If gmane is actually posting them to all cross- posted groups, subscription wouldn't matter. If it's not, and it's just your client managing things based on the message headers, then subscription would matter and you'd only see it in the otherwise broken group if you were subscribed to the unbroken one, because it's your client actually doing it, not gmane, and your client could only do it if it saw the message in the first place, which it could only do if it got the message on a different group. And yes, FWIW, my client (pan) does handle messages this way, because it processes messages by message-id, so as long as that header stays the same (as it should unless something's broken somewhere), if a message is cross-posted, it will appear in all groups it was posted to once my client sees it in just one of them. Well, it will if it's still in cache, anyway. My client has a tiny default cache, but I have it set to effectively unlimited, as I use the cache as a message archive for a number of mostly text groups, from gmane and other servers. I don't know what your client (gnus, based on the headers) does. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman