From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,a52626a9019b830 X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII Received: by 10.204.128.207 with SMTP id l15mr1068591bks.4.1347850370956; Sun, 16 Sep 2012 19:52:50 -0700 (PDT) Path: q11ni104388366wiw.1!nntp.google.com!feeder1.cambriumusenet.nl!feed.tweaknews.nl!85.12.40.130.MISMATCH!xlned.com!feeder1.xlned.com!npeer.de.kpn-eurorings.net!npeer-ng0.de.kpn-eurorings.net!border2.nntp.ams2.giganews.com!border4.nntp.ams.giganews.com!border2.nntp.ams.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!news.bbs-scene.org!weretis.net!feeder4.news.weretis.net!news.mixmin.net!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Help writing first daemon Date: Wed, 12 Sep 2012 09:16:33 +0200 Organization: cbb software GmbH Message-ID: References: <3b3a796d-50e0-4304-9f8d-295fb2ed0e82@googlegroups.com> <1hrmrgblczf2p.x7ar7hqalypi.dlg@40tude.net> <6b311ca1-9630-4874-b068-2b6b08c1ffa9@googlegroups.com> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: FbOMkhMtVLVmu7IwBnt1tw.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: 8bit Date: 2012-09-12T09:16:33+02:00 List-Id: On Tue, 11 Sep 2012 13:50:27 -0700 (PDT), Maciej Sobczak wrote: > W dniu wtorek, 11 wrze�nia 2012 17:13:06 UTC+2 u�ytkownik Dmitry A. Kazakov napisa�: > >>>> But, if you consider running the middleware as a system service (daemon), >>>> the main reason for that would be the architecture of shared memory. >>> >>> No, there is no connection between these two concepts. >> >> The concepts are single vs. multiple instances middleware. > > No. System services and shared memory are low-level building blocks that > can be used to construct software that actually does something useful. > Whether that software exists in a single vs. multiple instances is a > matter of terminology that is defined on a much higher level and has > nothing to do with how many processes there are or how they communicate. Not the software, but states (and thus data). In a single instance middleware objects maintained by it are physically shared by all applications. That precludes I/O, like pipes. In a multiple instances middleware objects are replicated and some I/O is necessary to maintain consistency of a logical object, physically distributed across applications. > For example, a well known database server is said to exist in a single > instance, while being physically composed of many processes (presumably > system services) communicating with each other. These concepts exist on > different levels. E.g. DB vs. DB replica. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de