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,feeba31d5415227b X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!postnews.google.com!g43g2000cwa.googlegroups.com!not-for-mail From: "jimmaureenrogers@worldnet.att.net" Newsgroups: comp.lang.ada Subject: Re: Crosstalk Article from Aonix Date: 10 Feb 2006 07:20:30 -0800 Organization: http://groups.google.com Message-ID: <1139584829.987401.81260@g43g2000cwa.googlegroups.com> References: NNTP-Posting-Host: 209.194.156.4 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1139584838 6483 127.0.0.1 (10 Feb 2006 15:20:38 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 10 Feb 2006 15:20:38 +0000 (UTC) User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0),gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: g43g2000cwa.googlegroups.com; posting-host=209.194.156.4; posting-account=SqOfxAwAAAAkL81YAPGH1JdBwpUXw9ZG Xref: g2news1.google.com comp.lang.ada:2842 Date: 2006-02-10T07:20:30-08:00 List-Id: adaworks@sbcglobal.net wrote: > In a recent article about safety-critical software, the author, > an employee of Aonix, manages to avoid even one mention > of Ada. He seems to be unaware that, in the safety-critical > domain, Ada is still a much better option than Java. I had an email conversation with the author of that article. He is aware of Ada. He also claims that Ada is loosing market share in real-time applications. Looking into the safety-critical Java specification I find that Ben Brogsol has been credited with some work on the specification. Ben was deeply involved with the first Ada definition and the Ada 95 definition. The author is clearly trying to provide some marketing for safety- critical Java. He claims that most safety-critical code is currently being done in C and C++. He believes safety-critical Java is a better tool. While he answered many of my questions he did not answer my question about safety-critical Java's support for thread temporal self-determination. That is my term for the capability of a thread to maintain its own critical timing even in the face of conditional synchronization of shared resources. Ada provides the select command to allow a task to extract itself from an entry queue based upon various conditions, including a time-out. The Java model of conditional synchronization uses the wait() command. There are two versions of the wait() command, one with a time-out and one without a time-out. The problem is that the calling thread does not control the wait() command. It is called within the synchronized block. This would be like putting a timeout inside the queue handler of a protected entry. The calling thread has no control over its own timing. All threads calling a common synchronized block are treated the same. There is also still no queuing policy for the wait() command, although there is some defense against priority inversion with various priority promotion schemes. Jim Rogers