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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,1eef1e815cf70416,start X-Google-NewGroupId: yes X-Google-Attributes: gida07f3367d7,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Received: by 10.204.141.4 with SMTP id k4mr2299901bku.6.1338835757272; Mon, 04 Jun 2012 11:49:17 -0700 (PDT) Path: e27ni13371bkw.0!nntp.google.com!news1.google.com!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail From: Adam Beneschan Newsgroups: comp.lang.ada Subject: Distributed Systems Annex, data sharing between programs Date: Mon, 4 Jun 2012 11:49:16 -0700 (PDT) Organization: http://groups.google.com Message-ID: NNTP-Posting-Host: 66.126.103.122 Mime-Version: 1.0 X-Trace: posting.google.com 1338835757 19564 127.0.0.1 (4 Jun 2012 18:49:17 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Mon, 4 Jun 2012 18:49:17 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=66.126.103.122; posting-account=duW0ogkAAABjRdnxgLGXDfna0Gc6XqmQ User-Agent: G2/1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Date: 2012-06-04T11:49:16-07:00 List-Id: I haven't had much need to look at the Distributed Systems Annex until rece= ntly. I'm finding that the answer to a simple question is eluding me: Can = the execution of a single partition be part of the executions of two or mor= e Ada program executions (whether executions of the same program, or of dif= ferent programs)? To explain further: Suppose a program P WITH's a Remote_= Call_Interface package R, and R has global data in its body, and R provides= operations that modify and retrieve this data. Suppose that R (and everyt= hing it needs) is put into its own partition, while the rest of P is put in= to another partition. Now, if the partition containing R is run just once, = and the other partition is executed multiple times, do they share the same = data in R's body? That is, if one execution of P calls a routine that modi= fies the global data, and another execution calls a routine that retrieves = it, will the second execution retrieve the data that was set by the first e= xecution? Similarly, suppose that two different programs WITH R, but the p= artition containing R is executed just once; do the two programs share the = data in R's body? My first impression is that the answer is "no". The introduction to Annex = E talks about "multiple partitions working cooperatively as part of a singl= e Ada program" and other similar wording, which seems to preclude the possi= bility of partitions being part of more than one program. Also, the note i= n E(7) says that the resulting execution is semantically equivalent if the = program is partitioned differently; and since two executions of the same pr= ogram obviously can't share data like this if the entire program is put int= o one partition, it wouldn't be semantically equivalent if they shared data= when R is put in its own partition. Still, 10.2 is somewhat vague about th= e different ways partitions can be executed, and I'm confused by examples s= uch as=20 http://www.adacore.com/adaanswers/gems/gem-111-the-distributed-systems-anne= x-part-5-embedded-name-server that appears to be set up so that multiple executions of the same "client" = partition cause data to accumulate in a server partition. This strikes me a= s being outside of the paradigm defined by the RM--but is it, or am I just = confused? If my understanding is correct, my next question is: is there any language-= defined support for sharing data between programs (besides file I/O), or do= es this require using an outside library for (say) socket communication or = memory sharing?=20 -- thanks, Adam