OPC

les lestyrrell at spamcop.net
Tue Feb 17 09:26:27 UTC 2004


Yeah, the SOAP-based protocol was being discussed a few years ago.  In the
meantime, plenty of COM-based infrastructure has been put in place.

The sickening thing... is to go through all the agony of building a
Smalltalk-based OPC Server ( and all the unbelievable crap that entails ),
and then turn around and pick up something like OpenTalk and start using it
in a few hours to do things that OPC ( or COM, or for that matter, DCOM )
could never dream of doing.  But... the world loves them typed languages.
The sicker thing about COM was feeling good about achieving things, not
because they were significant capabilities, but because they were so
freaking hard to achieve.

Even funnier.. to discover that OPC via DCOM is not exactly a preferred way
of doing things.  Nope.  That entails grief that most players would rather
not have.  Instead, they write their own vendor-specific protocols to do the
networked part, and rely on OPC to hook clients & servers up within the
confines of a single machine.  Matrikon is doing this game as well... a
middle netware for OPC.  What a seriously whacked world.

Now, if you could only compete with WonderWare... then you could leverage
all those OPC Servers out there and run pure Smalltalk from the UI down to
the clients.  It would be a *lot* easier to manage and maintain.  By
definition, if not outright assertion.  C++, Java, VB, whatever... there is
absolutely no advantage to any of those languages in that environment.

So, if that is what you are doing- Squeak as the UI, on the client side-
then save yourself a huge amount of trouble and pick up a third-party OPC
client dll.  Figure out ways to use Squeak as the UI, and as a means for
more effectively networking any solution you are building.

Good luck!

- les


----- Original Message ----- 
From: "Brian Brown" <brian at teuton.org>
To: "Lynn Hales" <lhales at earthlink.net>; "The general-purpose Squeak
developers list" <squeak-dev at lists.squeakfoundation.org>
Sent: Monday, February 16, 2004 6:14 PM
Subject: Re: Re[2]: OPC


> Quoting Lynn Hales <lhales at earthlink.net>:
>
> > Hello Les,
> >
> > Thanks Les,  evil probably but the entire control industry has selected
> > it as a communication standard.  Lynn
> >
>
> Actually, if you go to opcfoundation.org, you will see that the
proprietary DCOM
> based microsoft protocol is being phaased out and they are going to use
XML-RPC
> based protocols instead. I have agree with Les, and think the move to
XML-RPC is
> a smart one, bringing into the the 20th century, let alone the 21st :-)
>
> My .02 cents
>
>
> > l> OPC! EVIL!!!!
> >
> > l> Actually, spent a lot of time partially implementing an OPC Data
Access
> > l> Server ( & Client ) in VisualWorks.  In the end, we found a
third-party
> > DLL
> > l> from WinTech that we've been using since and have been pretty happy
with.
> > l> You could probably hook that up using FFI pretty easily.  The DLL is
> > around
> > l> $1000, one-time payment for unlimited use & source.  Money well
spent,
> > l> actually.
> >
> > l> Also, check out Matrikon for some handy OPC tools that you can
download.
> > l> Very handy for verifying that your server is working properly.
> >
> > l> - les
> >
> >
> >
> > l> ----- Original Message ----- 
> > l> From: "Brian Brown" <rbb at techgame.net>
> > l> To: "The general-purpose Squeak developers list"
> > l> <squeak-dev at lists.squeakfoundation.org>
> > l> Sent: Sunday, February 15, 2004 8:54 PM
> > l> Subject: Re: OPC
> >
> >
> > >>
> > >> On Feb 14, 2004, at 3:20 PM, Lynn Hales wrote:
> > >>
> > >> > I was wondering if anyone had experimented with OPC client and
servers
> > >> > applications within Squeak?  If so I would love to hear.
> > >> >
> > >>
> > >> By OPC are you referring the Microsoft protocol to control hardware
> > >> devices like video switches,etc?
> > >>
> > >> If so, I don't know of any in Squeak.
> > >>
> > >>
> > >> > -- 
> > >> > Best regards,
> > >> >  Lynn                            mailto:lhales at earthlink.net
> > >> >
> > >> >
> > >>
> > >>
> > >>
> >
> >
> >
> >
> >
> > -- 
> > Best regards,
> >  Lynn                            mailto:lhales at earthlink.net
> >
> >
> >
>
>
> -- 
>
>
>




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