From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 24121 invoked from network); 8 Feb 2023 22:41:57 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 8 Feb 2023 22:41:57 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id C68AA40E2C; Thu, 9 Feb 2023 08:41:21 +1000 (AEST) Received: from mail-lj1-f179.google.com (mail-lj1-f179.google.com [209.85.208.179]) by minnie.tuhs.org (Postfix) with ESMTPS id 5BA3140D93 for ; Thu, 9 Feb 2023 08:41:17 +1000 (AEST) Received: by mail-lj1-f179.google.com with SMTP id h17so85529ljq.4 for ; Wed, 08 Feb 2023 14:41:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:subject:message-id:date:from:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=zsszRcx0tIX0TtH7xSZE1M36VPBpoGeiShsHX3vvyDc=; b=O7gewhlRNaXc2BOot1MjY9PTHUc8p5fHY46j7RaoNYtvPx2CxnabvgEhEANzBInhlY X323/gc0yPKj5BdqqR55cXFaDc5ltZr8PAtpDDWGo3LXSjs9qBiaKDcPahC+1RklWIdu xf9jeqR7Hp06dKscoaEXLKBOUa/LqqNgf/h+cblDcYYfnMI9hZPJaiaQhiO8BsGc1rtc bw5OdE58QQ1fGuSUHKirSVwLnsyVs47oX/5LUEI2VKkDUnvXnB0hlSEYKgyy8+gzIms+ 0+nH56FPSvcnIWHOHu7wbBzIm5YmxEd9STr84ryuzz9ZlyHSkVvoYSjvAUidnUfmpKaB 1Hfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=zsszRcx0tIX0TtH7xSZE1M36VPBpoGeiShsHX3vvyDc=; b=fOhvIuuNOR9bEV8Sm3C1yLLCyh3p40JRHoJLQ6gzuX4Uaks+4CimigBYGxPmavwBOU LhPXb3slKkgjZ4BQOKXHwDyum8oeD7T035cl18LKiiLX9eIuGTrH7FfLUUDYX33NCRXv 9SR0bPamAABGRniEvd4inG5e5p1HoXLUuoTp0SI9HNnfECt7kKAxNi4MkQ8BTp2aepBJ 4GUwAM9/NP7hhSgypAzfW4iKt6hZRnICcXyaFAHI1zytonJDTZ6CyLvdOuGMVozZLJuk I9vyEeaINP7XRsW1+cRYiIer3Zjhzb11QMuTqzfsncg4ZI1siYRoECp1U89PdqC9r7LR 7+uA== X-Gm-Message-State: AO0yUKWjbAFMeCPEa1Wu3mz373zh0OuH8bAYCsP/7cg3G/6tEtnGRCW/ ggWYrqK7Nm50V0/gGYL79L4FGSQ/s7AnethWs/QB+4GLfc8= X-Google-Smtp-Source: AK7set97rqeAFMaaaZ+oiyxLmVOvdA27pqQmi0tPSy3b8pXlFjMr95yZe3ZKz9zlVF6SS/0sUt9Etesmw2BVBbQzCME= X-Received: by 2002:a05:651c:2cf:b0:292:fae4:f6ce with SMTP id f15-20020a05651c02cf00b00292fae4f6cemr1301845ljo.108.1675896015641; Wed, 08 Feb 2023 14:40:15 -0800 (PST) MIME-Version: 1.0 From: Dan Cross Date: Wed, 8 Feb 2023 17:39:39 -0500 Message-ID: To: Doug McIlroy , TUHS Content-Type: multipart/alternative; boundary="000000000000b1625e05f437f27d" Message-ID-Hash: EY455C4PP2U4C6WD75ZLW2AXOXDNTHUZ X-Message-ID-Hash: EY455C4PP2U4C6WD75ZLW2AXOXDNTHUZ X-MailFrom: crossd@gmail.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Unix "Multiplexed Files" List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --000000000000b1625e05f437f27d Content-Type: text/plain; charset="UTF-8" The subject of Communication Files on DTSS came up recently, and Doug linked to this wonderful note: https://www.cs.dartmouth.edu/~doug/DTSS/commfiles.pdf Over on the Multicians list, I raised a question about the history of the DTSS emulator on Multics in response to that, which sadly broke down into antagonism, the details of which aren't terribly interesting. But Barry Margolin suggested that the closest modern Unix analogue of Communication Files were pseudo-TTYs, that had generated a dustup here. Doug's note suggests that Plan 9's userspace filesystems, aided and abetted by mutable namespaces and 9P as a common sharing mechanism, were a closer analogy. But I wonder if multiplexed files were perhaps an earlier analogue; my cursory examination of mpx(2) shows some similarities to the description of the DTSS mechanism. But I confess that I know very little about these, other than that they seem to be an evolutionary dead end (they don't survive in any modern Unix that I'm aware of, at any rate). I don't see much about them in my archives; Paul Ruizendaal mentioned them tangentially in 2020 in relation to non-blocking IO: they are, apparently, due to Chessen? Does anyone have the story here? - Dan C. --000000000000b1625e05f437f27d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
The subject of Communication Files on DTSS came up recentl= y, and Doug linked to this wonderful note: https://www.cs.dartmouth.edu/~doug/DTSS/c= ommfiles.pdf

Over on the Multicians list, I raised a= question about the history of the DTSS emulator on Multics in response to = that, which sadly broke down into antagonism, the details of which aren'= ;t terribly interesting. But Barry Margolin suggested that the closest mode= rn Unix analogue of Communication Files were pseudo-TTYs, that had generate= d a dustup here. Doug's note suggests that Plan 9's userspace files= ystems, aided and abetted by mutable namespaces and 9P as a common sharing = mechanism, were a closer analogy.

But I wonder if = multiplexed files were perhaps an earlier analogue; my cursory examination = of mpx(2) shows some similarities to the description of the DTSS mechanism.=

But I confess that I know very little about these= , other than that they seem to be an evolutionary dead end (they don't = survive in any modern Unix that I'm aware of, at any rate). I don't= see much about them in my archives; Paul Ruizendaal mentioned them tangent= ially in 2020 in relation to non-blocking IO: they are, apparently, due to = Chessen?

Does anyone have the story here?

=C2=A0 =C2=A0 =C2=A0 =C2=A0 - Dan C.

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