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-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,ebdcfc7163c60d32 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-09-24 18:19:59 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!arclight.uoregon.edu!wn4feed!worldnet.att.net!bgtnsc05-news.ops.worldnet.att.net.POSTED!not-for-mail Message-ID: <3D910F02.9090006@worldnet.att.net> From: Jim Rogers User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:0.9.4) Gecko/20011128 Netscape6/6.2.1 X-Accept-Language: en-us MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Distributed programming in heterogeneous platforms References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 25 Sep 2002 01:19:58 GMT NNTP-Posting-Host: 12.86.32.85 X-Complaints-To: abuse@worldnet.att.net X-Trace: bgtnsc05-news.ops.worldnet.att.net 1032916798 12.86.32.85 (Wed, 25 Sep 2002 01:19:58 GMT) NNTP-Posting-Date: Wed, 25 Sep 2002 01:19:58 GMT Organization: AT&T Worldnet Xref: archiver1.google.com comp.lang.ada:29324 Date: 2002-09-25T01:19:58+00:00 List-Id: Robert C. Leif wrote: > What would happen if the Ada Distributed Systems Annex were used with > XML messages that were validated by both the sender and receiver with > the same XML schema? > Bob Leif > Clean but painfully slow data communication would be achieved. XML forces all data to be encoded as strings. There is also a significant overhead in XML tags being passed with the data. This allows strong platform independence, but is very inefficient. For most applications the inefficiencies are not important. The latency accessing a local or remote database may be orders of magnitude greater than the XML coding/decoding inefficiencies. For hard real time command and control systems the overhead of XML can be unbearable. In the robotics program I mentioned earlier we could not even bear the overhead of full IP protocol. We needed to send all our data at lower levels in the OSI stack. We were given a very narrow RF bandwidth and a maximum transmission rate of 24000 baud, with expected average transmission rates closer to 19.2K baud. In our situation XML would have been unacceptable. Jim Rogers