Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Schnell]

On 10/21/2015 12:19 PM, Mark Morgan Lloyd wrote:


In practical terms, there have been a number of "must-have" features 
in the IDE and LCL- frames as a particular example- which have 
mandated moving onto a "bleeding-edge" FPC. My experience with 
Lazarus-1.4.0 and FPC 3.0 rc1 has been generally good, particularly 
once I'd moved off 2014-era Raspbian.


Lazarus' official releases are a lot more frequently than fpc's. So an 
addition to Lazarus that needs fpc 3.x needs to be delayed until there 
is an RC of a Lazarus version that officially is recommended to be used 
with fpc 3.x and hence will be "Bundled" with same in distributions.


-Michael


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Re: [Lazarus] TInetSocket usage - any documentation available?

[Mark Morgan Lloyd]

Michael Schnell wrote:

On 10/21/2015 10:35 AM, Mark Morgan Lloyd wrote:


So noting your concern with events, the real question is still which 
libraries etc. he should be running to implement a socket client 
reliably in a console program. Or alternatively, how best to implement 
a Windows-style service using Lazarus, which doesn't mandate a screen 
and an initial login.


In a private message I suggested to him to try (and supposedly help to 
improve) my "ActiveNoGui" Widget Type (Linux) Library that is intended 
as a workalike for a Delphi Service-Application.


If that's something you're actively working on it would sound like an 
eminently sensible suggestion.



But same needs fpc 3.x and Bo does not want to move to same.


I think that reluctance is ungrounded, and I'd hope that as he builds up 
more confidence on Linux he'll reconsider.


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Re: [Lazarus] TInetSocket usage - any documentation available?

[Mark Morgan Lloyd]

Michael Schnell wrote:

On 10/21/2015 11:28 AM, Mark Morgan Lloyd wrote:


If that's something you're actively working on it would sound like an 
eminently sensible suggestion.


I had been working on that on and off (and discussing it here) for a 
long time, but there had been no point in pushing it (once I were not in 
need of using it myself any more), before fpc 3.x is an official release 
so that a non-svn-user would be able to compile it (and hence would 
break Lazarus in case it would be included).


Tracking the "best" version of FPC for any given Linux release can be 
tricky. In retrospect it's unfortunate that the Lazarus 1.0 release 
wasn't delayed until FPC 3.0, as a memorable combination against which 
programs meant for distribution to people who didn't normally run FPC 
etc. could be tested.


In practical terms, there have been a number of "must-have" features in 
the IDE and LCL- frames as a particular example- which have mandated 
moving onto a "bleeding-edge" FPC. My experience with Lazarus-1.4.0 and 
FPC 3.0 rc1 has been generally good, particularly once I'd moved off 
2014-era Raspbian.


--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Schnell]

On 10/21/2015 11:28 AM, Mark Morgan Lloyd wrote:


If that's something you're actively working on it would sound like an 
eminently sensible suggestion.
I had been working on that on and off (and discussing it here) for a 
long time, but there had been no point in pushing it (once I were not in 
need of using it myself any more), before fpc 3.x is an official release 
so that a non-svn-user would be able to compile it (and hence would 
break Lazarus in case it would be included).


-Michael

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Schnell]

On 10/21/2015 12:33 AM, Bo Berglund wrote:
As Mark Morgan Lloyd has pointed out I *really* need to create an 
encapsulated class for the TCPIP communications so I can use this as 
an alternate component in the existing object and for this I need to 
implement an onReceive event to plug the incoming data into it


Sorry to be a PITA, again, but a command line application (which in the 
other message you said you would want to do) does not support throwing 
events from threads out of the box. (There is no Lazarus Linux workalike 
for a Delphi Service Application.). You would have to implement your own 
"main loop" to make this happen.


That is why, to use the standard Lazarus and Delphi programming 
paradigms, I suggested to do a normal Lazarus GUI application on the RasPi.


-Michael

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Mark Morgan Lloyd]

Bo Berglund wrote:


And it looks more complete, there is a chat example which implements a
bidirectional system using a thread too.
I will try to stuff this into the existing code if possible...

As Mark Morgan Lloyd has pointed out I *really* need to create an
encapsulated class for the TCPIP communications so I can use this as
an alternate component in the existing object and for this I need to
implement an onReceive event to plug the incoming data into it.
Otherwise I am in for a really big rewrite of the class.


Although I think that was more in the context of trying to keep 
everything together if handling e.g. both serial comms and something 
over a socket.


I usually end up with odd requirements that force me to go to low-level 
serial port access, or a low-level socket... needing to log times 
accurately, a special-purpose telnet server and so on. The result of 
this is that I'm often better served with a low-level thread (and 
possibly select() calls etc.), with the interface to the main program 
being a buffer.


So find some way of encapsulating stuff, but I'd suggest not focussing 
on that to the exclusion of getting the main job done.


--
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markMLl .AT. telemetry.co .DOT. uk

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Mark Morgan Lloyd]

Michael Schnell wrote:

On 10/21/2015 12:33 AM, Bo Berglund wrote:
As Mark Morgan Lloyd has pointed out I *really* need to create an 
encapsulated class for the TCPIP communications so I can use this as 
an alternate component in the existing object and for this I need to 
implement an onReceive event to plug the incoming data into it


Sorry to be a PITA, again, but a command line application (which in the 
other message you said you would want to do) does not support throwing 
events from threads out of the box. (There is no Lazarus Linux workalike 
for a Delphi Service Application.). You would have to implement your own 
"main loop" to make this happen.


That is why, to use the standard Lazarus and Delphi programming 
paradigms, I suggested to do a normal Lazarus GUI application on the RasPi.


Which is fine as a testbed, but not necessarily for production use. It's 
particularly not fine if you want to start it on a regular basis from 
cron or whatever, which I think Bo has already settled on.


I'm very much in two minds on this. I'm intermittently working on a 
couple of fairly large programs which have elements of both daemon and 
UI, having them as standard Lazarus apps makes inspection and debugging 
much easier but inserts a large amount of complexity- X11, the widget 
set (GTK or Qt), all of the LCL stuff- all of which has the potential 
for bugs and unintended interactions.


Even if Bo did decide not to use cron but instead to have a Lazarus app 
with its own embedded timing, he'd still have to organise startup and 
having a screen- real or simulated- to run it on. And since a Raspberry 
Pi needs a keyboard etc. in order to have a local screen, and since he's 
not sorted out automatic VNC startup etc., I don't think this is the way 
for him to go.


So noting your concern with events, the real question is still which 
libraries etc. he should be running to implement a socket client 
reliably in a console program. Or alternatively, how best to implement a 
Windows-style service using Lazarus, which doesn't mandate a screen and 
an initial login.


--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Schnell]

On 10/21/2015 10:35 AM, Mark Morgan Lloyd wrote:

Which is fine as a testbed, but not necessarily for production use. 
It's particularly not fine if you want to start it on a regular basis 
from cron or whatever, which I think Bo has already settled on.
I fully agree: doing a cron-driven timing and porting Delphi code does 
not go together well.


-Michael

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Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Schnell]

On 10/21/2015 10:35 AM, Mark Morgan Lloyd wrote:


So noting your concern with events, the real question is still which 
libraries etc. he should be running to implement a socket client 
reliably in a console program. Or alternatively, how best to implement 
a Windows-style service using Lazarus, which doesn't mandate a screen 
and an initial login.


In a private message I suggested to him to try (and supposedly help to 
improve) my "ActiveNoGui" Widget Type (Linux) Library that is intended 
as a workalike for a Delphi Service-Application.


But same needs fpc 3.x and Bo does not want to move to same.

-Michael


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Re: [Lazarus] TInetSocket usage - any documentation available?

[Bo Berglund]

On Wed, 23 Sep 2015 10:21:58 +0200 (CEST), Michael Van Canneyt
 wrote:

>On Wed, 23 Sep 2015, Bo Berglund wrote:
>
>> I have looked for a native FPC TCP/IP socket to use as a replacement
>> for a serial port component and I discovered the ssockets unit that
>> ships with FPC and contains a TInetSocket class.
>> This seemed useful.
>
>> The data shifted through the socket will be EXACTLY the same as was
>> earlier transferred by RS232.
>>
>> Any suggestions on where I can find suitable documentation?
>>
>
>Shortly said: There is none.
>
>If the various demo programs are not understandable for you, you are out of 
>luck :(
>
>Now, from what you describe, all you need to do is use the read/write
>methods to send and receive data, just as in any stream: the client 
>TInetSock is a TStream descendent.
>
>Thread programming is not so difficult, but I am not convinced that for the 
>use case you describe, threads are really needed (despite suggestions to the 
>contrary on this list).

Thanks for the pointers!
Back in September I was looking for the solution on this but at the
time not yet on an RPi2, but on Windows. I was also then adviced to
search for an example of TInetSocket and had a look at ssockets usage
in the example:
lazarus\fpc\2.6.4\source\packages\fcl-base\examples\dsockcli.pp

But the example is pretty limited regarding how one actually
communicates using the sockets provided by ssockets.
All it seems to do is to connect to a server and write the same line
of text 10 times over and then quit.

What I must do is plug a socket into the existing code where there is
bidirectional data transfers using a receive event and there will be a
response for each packet sent.
In another thread on the fpc list I was directed towards an example I
could download from:
https://github.com/silvioprog/tcpipcomp

And it looks more complete, there is a chat example which implements a
bidirectional system using a thread too.
I will try to stuff this into the existing code if possible...

As Mark Morgan Lloyd has pointed out I *really* need to create an
encapsulated class for the TCPIP communications so I can use this as
an alternate component in the existing object and for this I need to
implement an onReceive event to plug the incoming data into it.
Otherwise I am in for a really big rewrite of the class.

Struggling on...


-- 
Bo Berglund
Developer in Sweden


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Re: [Lazarus] TInetSocket usage - any documentation available?

[Mark Morgan Lloyd]

Michael Van Canneyt wrote:

On Wed, 23 Sep 2015, Bo Berglund wrote:


I have looked for a native FPC TCP/IP socket to use as a replacement
for a serial port component and I discovered the ssockets unit that
ships with FPC and contains a TInetSocket class.
This seemed useful.



The data shifted through the socket will be EXACTLY the same as was
earlier transferred by RS232.

Any suggestions on where I can find suitable documentation?



Shortly said: There is none.

If the various demo programs are not understandable for you, you are out 
of luck :(


Now, from what you describe, all you need to do is use the read/write
methods to send and receive data, just as in any stream: the client 
TInetSock is a TStream descendent.


Thread programming is not so difficult, but I am not convinced that for 
the use case you describe, threads are really needed (despite 
suggestions to the contrary on this list).


I'd suggest that the bottom line there is making the socket code oresent 
the same interface as the existing RS232 code.


I've not used it so I'm not happy giving advice, but Google definitely 
turns up a few TInetSocket examples, such as


http://ejemplos.mis-algoritmos.com/programa-cliente-de-tinetsocket

I agree that it's unfortunate that there's not one in the fcl-net 
package itself, but (again via Google) there's a minimal example in 
fcl-web/src/base/fcgigate.pp which might help. Also via a local grep I 
notice references in fcl-base/examples/dsockcli.pp and 
utils/debugsvr/dbugintf.pp which might turn out to be useful.


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Re: [Lazarus] TInetSocket usage - any documentation available?

[Michael Van Canneyt]

On Wed, 23 Sep 2015, Bo Berglund wrote:


I have looked for a native FPC TCP/IP socket to use as a replacement
for a serial port component and I discovered the ssockets unit that
ships with FPC and contains a TInetSocket class.
This seemed useful.



The data shifted through the socket will be EXACTLY the same as was
earlier transferred by RS232.

Any suggestions on where I can find suitable documentation?



Shortly said: There is none.

If the various demo programs are not understandable for you, you are out of 
luck :(

Now, from what you describe, all you need to do is use the read/write
methods to send and receive data, just as in any stream: the client 
TInetSock is a TStream descendent.


Thread programming is not so difficult, but I am not convinced that for the 
use case you describe, threads are really needed (despite suggestions to the 
contrary on this list).


Michael.

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[Lazarus] TInetSocket usage - any documentation available?

[Bo Berglund]

I have looked for a native FPC TCP/IP socket to use as a replacement
for a serial port component and I discovered the ssockets unit that
ships with FPC and contains a TInetSocket class.
This seemed useful.
So I put together a test console application in Lazarus 1.4.0 where I
had this in order to verify that FPC would find it:
[code]
procedure TSSRemoteTestApp.DoRun;
var
  ErrorMsg: String;
  FSSConn: TInetSocket;
begin
  //Stuff added by Lazarus removed .
  { add your program here }
  FSSConn := TInetSocket.Create('10.0.0.2', 2001);
  // stop program loop
  Terminate;
end;
[/code]
After I added the ssockets unit to the uses clause this compiled and
so it seems like it will work.

My next problem is actually finding some description on what one can
do with that object...
Is there somewhere a comprehensive guide on usage of this socket in a
simple case as mine:
- Connect once and keep connection until end of program
- Send commands and binary data via a TCP/IP socket to the other end
- Fire an event when there are data received so they can be handled

I think that TInetSocket is actually blocking so I would have to use
some thread or such to retrieve incoming data and decode that and feed
it to the main program level for processing.
But how? I have only minimal info on what the TInetSocket can actually
do.
When I google TInetSocket I get results that are not referring to this
socket at all. Instead they refer to general TCP/IP articles or
descriptions of OTHER socket implementations. :(

My reason for this:
I have a quite large Delphi project for communications via RS232 to a
data collection system. This was developed over several years.
Now I need to create a new application that must run on an ARM
embedded platform (first test will be Raspberry Pi2) and communicate
via WiFi to the data collection system. It must use my existing
Delphi7 classes to control the instrument and manage the data, but
replace the RS232 component with a TCP/IP socket component available
on FPC.
The data shifted through the socket will be EXACTLY the same as was
earlier transferred by RS232.

Any suggestions on where I can find suitable documentation?

-- 
Bo Berglund
Developer in Sweden


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