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,eb0daafec4ae827a X-Google-Attributes: gid103376,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news2.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!wns13feed!worldnet.att.net!attbi_s22.POSTED!53ab2750!not-for-mail From: "Jeffrey R. Carter" User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: High-integrity networking References: <1191845623.383675.190820@d55g2000hsg.googlegroups.com> <_VwOi.141398$Fc.15278@attbi_s21> <1191935853.244559.87440@o80g2000hse.googlegroups.com> In-Reply-To: <1191935853.244559.87440@o80g2000hse.googlegroups.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: NNTP-Posting-Host: 12.201.97.213 X-Complaints-To: abuse@mchsi.com X-Trace: attbi_s22 1191951453 12.201.97.213 (Tue, 09 Oct 2007 17:37:33 GMT) NNTP-Posting-Date: Tue, 09 Oct 2007 17:37:33 GMT Organization: AT&T ASP.att.net Date: Tue, 09 Oct 2007 17:37:33 GMT Xref: g2news2.google.com comp.lang.ada:2387 Date: 2007-10-09T17:37:33+00:00 List-Id: Maciej Sobczak wrote: > > I understand this, but this approach has some limitations for me. > First of all, it limits the scope of discussion to Ada only, and every > non-trivial distributed system I have seen so far is heterogenous in > the sense of technology coverage. > I would like to understand the issues in such systems to get a better > view on the architectural and functional aspects of communication that > promotes verification and analysis of the whole. As I've already > pointed, I understand that Ravenscar can be used as a "mental > template" that can be extrapolated to distributed systems. This is > perfectly fine. Still, if there is anything that is particularly worth > reading *in addition*, I'm looking forward to get some pointers. Ravenscar is also Ada only, so you can't really talk about it in a heterogeneous system. I take it you're trying to apply the spirit of Ravenscar to heterogeneous distributed systems, but you're pretty much on your own there. I'd probably design such a system as a distributed/Annex-E Ravenscar system, then try to ensure that the non-Ada parts are equivalent to what an Ada implementation would be, and that all communications are equivalent to what would take place in a fully Annex-E implementation. > I have already found CSP (Communicating Sequential Processes), which > is one possible approach, although what I have seen up to now leaves > some "minor" details in the air, like the startup of the whole system. > Ravenscar can afford this, because it's the language implementation > that has to more or less transparently take care of all these issues, > but heterogenous systems might need some more explicit handling. CSP was the basic model for Ada-83 tasking: tasks with entries calling each other. That scales nicely to one task per computer. -- Jeff Carter "You cheesy lot of second-hand electric donkey-bottom biters." Monty Python & the Holy Grail 14