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RE: Objects, processes, and encapsulation



Currently, we are experimenting with RTLinux for building control
applications. We use RTLinux purely for its operating system resources
(network, windows, filesystem etc.). Our real-time control application
is build with our "CSP for C++" (CTC++) and runs on one real-time thread
(whatever that is?). CTC++ contains a real-time (nestable) scheduler and
runs on top of RTLinux. Other Linux threads are used for the Linux (soft
or non real-time) tasks that are related to the operating system. "CSP
for C++" (CTC++) is much easier to use than the multithreading (POSIX)
stuff for our control engineer students. The learning cycle for CTC++ is
much lower than learning and mastering POSIX. Special channels
communicate with the OS resources and the Linux tasks. These channels
use the rt-fifo's.

We use OO to model the software, but OO and C++ alone would easily
result in a sequential control application. Such sequential application
inherits all the disadvantages of a single thread of control. Control
applications are concurrent in many aspects. Multithreading breaks down
the clean OO principles, simply because POSIX is not OO (sorry Oyvind
for repeating this :)). CSP does match naturally with OO and CSP
encapsulates the (hard to get right) POSIX stuff.

Our experimental setup is a 2-degree camera setup that is controlled by
the RTLinux system whereby the images are seen over the internet.

Gerald.

> -----Original Message-----
> From: Lawrence Dickson [mailto:tjoccam@xxxxxxxxxxxxx] 
> Sent: dinsdag 9 oktober 2001 17:53
> To: IanPage99@xxxxxxx; P.H.Welch@xxxxxxxxx
> Cc: java-threads@xxxxxxxxx; ldickson@xxxxxxxxxx; occam-com@xxxxxxxxx
> Subject: Re: Objects, processes, and encapsulation
> 
> 
> Don't be so gloomy Ian... If we can just get a WORKING
> MODEL over something like RTLinux we can show the world
> how easy it is to do things that are incredibly
> difficult in OO. Like sensors and robotics. 
> 
> I love the RTLinux model because it has the single
> bloated thread where you can do everything the 
> gooey standard way... with our stuff underneath
> it, behaving rationally.
> 
> Larry
> 
> From owner-occam-com-out@xxxxxxxxx Tue Oct  9 04:28:08 2001
> From: IanPage99@xxxxxxx
> Date: Tue, 9 Oct 2001 07:27:31 EDT
> Subject: Re: Objects, processes, and encapsulation
> To: P.H.Welch@xxxxxxxxx
> CC: java-threads@xxxxxxxxx, occam-com@xxxxxxxxx
> MIME-Version: 1.0
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> 
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> 
> In a message dated 08/10/2001 13:41:59 GMT Daylight Time, 
> P.H.Welch@xxxxxxxxx 
> writes:
> 
> 
> > It's strange what the Object Orientists have achieved ... they have 
> > managed to make serial programming as dangerous as unconstrained 
> > concurrent programming.  .....
> 
> Well said Peter. As usual of course, saying it is unlikely
> to make much difference to the progress of events (especially, 
> as you say, this group is mostly about preaching to the already 
> converted), but not saying it certainly won't!
> 
> Cheers,
> Ian
> 
> 
> --part1_158.22e1e50.28f43923_boundary
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> 
> <HTML><FONT FACE=arial,helvetica><FONT  SIZE=2>In a message 
> dated 08/10/2001 13:41:59 GMT Daylight Time, 
> P.H.Welch@xxxxxxxxx writes: <BR> <BR> <BR><BLOCKQUOTE 
> TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 
> 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">It's strange what 
> the Object Orientists have achieved ... they have managed 
> <BR>to make serial programming as dangerous as unconstrained 
> concurrent <BR>programming. &nbsp;.....</FONT><FONT  
> COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" 
> LANG="0"></BLOCKQUOTE> <BR></FONT><FONT  COLOR="#000000" 
> SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> <BR>Well 
> said Peter. As usual of course, saying it is unlikely <BR>to 
> make much difference to the progress of events (especially, 
> <BR>as you say, this group is mostly about preaching to the already 
> <BR>converted), but not saying it certainly won't!
> <BR>
> <BR>Cheers,
> <BR>Ian
> <BR></FONT></HTML>
> 
> --part1_158.22e1e50.28f43923_boundary--
> 
>