RE: SDL-News: On implementations


Subject: RE: SDL-News: On implementations
From: Flávio J. Moritz Jr. (flavio.moritz#digitro.com.br)
Date: Fri Aug 13 1999 - 12:46:20 GMT


The originator of this message is responsible for its content.
-----From "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br> to sdlnews -----

Humm, looks like Object Geode is better suited for this particular need.
Is there any online (Internet) manual of Object Geode, which I could take a
peek and understand how it implements SDL systems?

[]'s Flavio

> -----Original Message-----
> From: owner-sdlnews#sdl-forum.org
> [mailto:owner-sdlnews#sdl-forum.org]On
> Behalf Of Vibhor Agarwal
> Sent: Friday, August 13, 1999 1:45 AM
> To: Flávio J. Moritz Jr.
> Cc: sdlnews#sdl-forum.org
> Subject: Re: SDL-news: On implementations
>
>
> The originator of this message is responsible for its content.
> -----From Vibhor Agarwal <vibhor#lucent.com> to sdlnews -----
>
> Hi Flavio,
>
> I think this would be a good forum to discuss the kind of
> queries you have put.
> To supplement what you have written, I think we should
> finally be able to map our blocks and processes according
> to our requirements. I am using Object Geode and the POSIX
> run-time library suppports multi-threading. This
> middleware of database access could be a block/process and
> can interface with database. This block/process can
> be mapped to a task which will finally run as a thread of our
> main unix process.
> In my application, I have directly integrated database calls
> in SDL which according to your argument might not
> be a good idea because of time taken for database access...we
> can see the performance and if needed create a
> middleware thread as you have talked about.
>
> I would be delighted to see some people who are using Object
> Geode and are also interested in discussing
> implementaion details on this list.
>
> Regards,
> Vibhor
>
> Flávio J. Moritz Jr. wrote:
>
> > The originator of this message is responsible for its content.
> > -----From "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?="
> <flavio.moritz#digitro.com.br> to sdlnews -----
> >
> > Hi,
> >
> > I've been lurking on this list for a while now and haven't seen any
> > discussion on SDL tools.
> > Well, I not actually interested in talking about the tool
> itself, but rather
> > how people use these tools.
> > Let me give you an example.
> > I use Telelogic's tools (TAU) to design telecom applications.
> > It's (Telelogic's) C code generator implements the application.
> > Those applications are compiled and run on UNIX boxes.
> > Whenever I need to access a database server, I use interprocess
> > communications protocols to send messages to another UNIX
> process which in
> > turn uses the database API.
> > Just because I don't want my "SDL" app to block on a
> function call while
> > waiting for the database server.
> > So, I was wondering. How does anybody else do the same thing ?
> > How about shrinking this "middleware" into a thread ?
> > Wouldn't it be better ?
> > Can you see the kind of conversations I would like to have ?
> > Is this an appropriate forum for this ?
> > Can I start this kind of discussions here?
> > Does anybody knows a better forum for this?
> > Any mailing lists or newsgroups ?
> >
> > Please, don't take me wrong. I find people here very
> helpful. I just don't
> > want to botherFrom sdlnews-owner Fri Aug 13 06:46:23 1999
Received: (sdlforum#localhost) by sdl-forum.org (8.8.5) id GAA16755; Fri, 13 Aug 1999 06:46:23 -0600 (MDT)
From: "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br>
To: <sdlnews#sdl-forum.org>
Subject: RE: SDL-news: On implementations
Date: Fri, 13 Aug 1999 09:46:24 -0300
Message-ID: <000701bee589$daa095b0$5aa1a8c0#digitro.com.br>
MIME-Version: 1.0
Content-Type: text/plain;
        charset="iso-8859-1"
Content-Transfer-Encoding: 8bit
X-Priority: 3 (Normal)
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook 8.5, Build 4.71.2173.0
Importance: Normal
In-Reply-To: <00BBC23881EAD211A9CF00805FA96634303B65#EXCHANGE_SERVER>
X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300
Sender: owner-sdlnews#sdl-forum.org
Precedence: bulk
Reply-To: "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br>

The originator of this message is responsible for its content.
-----From "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br> to sdlnews -----

Sure, Yoni.
We do exactly the same thing here.
But, lets get back to the database access problem.
Let's say the SDL application wants to make a query on a table stored in a
MySQL, PostgreSQL or even Oracle database server.
I can't see how I can use the environment functions to make this query
without blocking the whole SDL system.
Because this query will actually be a function call. The application will
return from this function call only after completion of the query.
So, things would work this way:
- The SDL process wants to make a query on a DB server, thus sending a
signal to the environment;
- xOutEnv is called by the SDT main loop to handle this signal;
- In xOutEnv, a function from the database client API is called to handle
the query;
- Query takes a lot of time, meanwhile the SDL system is freezed on a DB
client API function call.
So I was wondering if I could put this DB function call on a separate thread
and use SDL_Output to send a signal from this thread to the original thread
informing query completion.
But people at Telelogic told me that SDL_Output is not thread-safe. They
said:
-- quote ---
"The solution is to implement a message sending/receiving protocol between
your database thread and the SDLthread. The protocol should use XInEnv and
XOutEnv to send/receive signals to the SDL system."
-- end quote ---
Well, that's exactly how we do it now and I tell you, it's really boring to
write this "middleware".
Unfortunately, I see no exit signal here. Thats the way it has to be done.
Oh, it just occured to me that a thread for you could be different from a
thread for me.
I'm talking about POSIX threads on UNIX OS processes.
A child thread shares most of the data from its parent thread, while a child
process doesn't.

Well, anyway, it's wonderful to see that I finally found a place to discuss
this kind of things.
Thanks.

[]'s Flavio

> -----Original Message-----
> From: owner-sdlnews#sdl-forum.org
> [mailto:owner-sdlnews#sdl-forum.org]On
> Behalf Of Yoni Rabinovich
> Sent: Friday, August 13, 1999 5:49 AM
> To: 'Fl?vio J. Moritz Jr.'; sdlnews#sdl-forum.org
> Subject: RE: SDL-news: On implementations
>
>
> The originator of this message is responsible for its content.
> -----From Yoni Rabinovich <YRABINOV#teledata.co.il> to sdlnews -----
>
> Hi Flavio,
>
> I developed a fairly large telecom application a few years ago with
> Telelogic's SDT (the SDL core of TAU).
> The way we handled issues like those you raise were by using the
> "environment" functions (xInEnv, xOutEnv etc.)
>
> The xInEnv function is called as part of the main loop of the SDT
> scheduler. Our SDT application ran on top of the pSOS Real
> Time OS, as a
> pSOS task (thread). External applications generated pSOS
> events when they
> wanted to pass data to the SDL system. The SDT main loop
> would check for
> such events in xInEnv, and translate them into SDL signals
> sent into the
> system. We designed it such that the SDL system would not
> block waiting for
> inputs from the external applications, so as not to you with things that aren't of your interest.
> >
> > []'s Flávio Moritz
> >
> > "The chase is better than the catch."
> >
> > -----End text from
> "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?="
> <flavio.moritz#digitro.com.br> to sdlnews -----
> > Join http://www.sdl-forum.org/Society/members.htm for extra
> SDL Forum Society benefits
> > For help, email "majordomo#sdl-forum.org" with the body of
> your email as:
> > help
> > or (iff this does not answer your question) email:
> owner-sdlnews#sdl-forum.org
>
>
> -----End text from Vibhor Agarwal <vibhor#lucent.com> to sdlnews -----
> Join http://www.sdl-forum.org/Society/members.htm for extra
> SDL Forum Society benefits
> For help, email "majordomo#sdl-forum.org" with the body of
> your email as:
> help
> or (iff this does not answer your question) email:
> owner-sdlnews#sdl-forum.org
>

-----End text from "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br> to sdlnews -----
Join http://www.sdl-forum.org/Society/members.htm for extra SDL Forum Society benefits
For help, email "majordomo#sdl-forum.org" with the body of your email as:
    help
or (iff this does not answer your question) email: owner-sdlnews#sdl-forum.org
 block the
> SDL system
> itself. On the other hand, the SDT task would "go to sleep"
> if there was
> nothing for it to do (i.e. no internal SDL signals or timers
> or external
> events pending).
>
> Regards,
>
> Yoni Rabinovitch
> R&D Team Leader
> ADC Teledata Communications
> 7 Ha'sadnaot St, Hertzlia, 46120, Israel
> email: yrabinov#teledata.co.il
> Phone: +972-9-9591741
> Fax : +972-9-9591444
>
> > -----Original Message-----
> > From: flavio.moritz#digitro.com.br
> [SMTP:flavio.moritz#digitro.com.br]
> > Sent: 12 August 1999 22:14
> > To: sdlnews#sdl-forum.org
> > Subject: SDL-news: On implementations
> >
> > The originator of this message is responsible for its content.
> > -----From "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?="
> > <flavio.moritz#digitro.com.br> to sdlnews -----
> >
> > Hi,
> >
> > I've been lurking on this list for a while now and haven't seen any
> > discussion on SDL tools.
> > Well, I not actually interested in talking about the tool
> itself, but
> > rather
> > how people use these tools.
> > Let me give you an example.
> > I use Telelogic's tools (TAU) to design telecom applications.
> > It's (Telelogic's) C code generator implements the application.
> > Those applications are compiled and run on UNIX boxes.
> > Whenever I need to access a database server, I use interprocess
> > communications protocols to send messages to another UNIX
> process which in
> > turn uses the database API.
> > Just because I don't want my "SDL" app to block on a
> function call while
> > waiting for the database server.
> > So, I was wondering. How does anybody else do the same thing ?
> > How about shrinking this "middleware" into a thread ?
> > Wouldn't it be better ?
> > Can you see the kind of conversations I would like to have ?
> > Is this an appropriate forum for this ?
> > Can I start this kind of discussions here?
> > Does anybody knows a better forum for this?
> > Any mailing lists or newsgroups ?
> >
> > Please, don't take me wrong. I find people here very
> helpful. I just don't
> > want to bother you with things that aren't of your interest.
> >
> > []'s Flávio Moritz
> >
> > "The chase is better than the catch."
> >
> >
> > -----End text from "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?="
> > <flavio.moritz#digitro.com.br> to sdlnews -----
> > Join http://www.sdl-forum.org/Society/members.htm for extra
> SDL Forum
> > Society benefits
> > For help, email "majordomo#sdl-forum.org" with the body of
> your email as:
> > help
> > or (iff this does not answer your question) email:
> > owner-sdlnews#sdl-forum.org
>
> -----End text from Yoni Rabinovich <YRABINOV#teledata.co.il>
> to sdlnews -----
> Join http://www.sdl-forum.org/Society/members.htm for extra
> SDL Forum Society benefits
> For help, email "majordomo#sdl-forum.org" with the body of
> your email as:
> help
> or (iff this does not answer your question) email:
> owner-sdlnews#sdl-forum.org
>

-----End text from "=?iso-8859-1?Q?Fl=E1vio_J._Moritz_Jr.?=" <flavio.moritz#digitro.com.br> to sdlnews -----
Join http://www.sdl-forum.org/Society/members.htm for extra SDL Forum Society benefits
For help, email "majordomo#sdl-forum.org" with the body of your email as:
    help
or (iff this does not answer your question) email: owner-sdlnews#sdl-forum.org



This archive was generated by hypermail 2a23 : Sun Jun 16 2013 - 10:41:40 GMT