[solved]null-terminated stream

einsTeIn.NET · 2008-07-22

Hi there,

afaik strings in NAV are containing their length in the first character. So, they are not null-terminated (like in C). I want to transfer some data to an external system. The connection type is socket and the data should be transfered as stream. The external system expects a null-termination at the end of a stream.
I did the following...

IF ISCLEAR(CC2) THEN 
  CREATE(CC2);
IF ISCLEAR(SBA) THEN 
  CREATE(SBA);

CC2.AddBusAdapter(SBA, 0);
OutMsg := CC2.CreateoutMessage('Sockets://localhost:5006');

OutS := OutMsg.GetStream();

OutS.WRITETEXT('Some Text 1');
OutS.WRITETEXT('Some Text 2');
OutS.WRITETEXT('Some Text 3');
OutS.WRITETEXT();

IF NOT OutMsg.Send(0) THEN
...

but the external system doesn't react. So, I wonder if the stream isn't null-terminated and the external system doesn't catch the message.

Xypher · 2008-07-22

You could try doing...

//nullchar declared as Text (length 1~) or Char, whatever you want
nullchar[1] := 0;

//...YourCode...

OutS.WRITETEXT('Some Text 1');
OutS.WRITETEXT('Some Text 2');
OutS.WRITETEXT('Some Text 3');
OutS.WRITETEXT(); 
OutS.WRITE(nullchar);

//...etc...

Let me know if it works

einsTeIn.NET · 2008-07-25

I'm not sure if I could test it like this

CU 50000 (single instance)

OnRun()
IF ISCLEAR(CC2) THEN
  CREATE(CC2);

IF ISCLEAR(SBA) THEN
  CREATE(SBA);

CC2.AddBusAdapter(SBA,0);
SBA.OpenSocket(6006,'');

CC2::MessageReceived(VAR InMessage : Automation "''.IDISPATCH")
InMsg := InMessage;

InS := InMsg.GetStream();

WHILE NOT (InS.EOS) DO BEGIN
  IF InS.READ(Txt) > 0 THEN
    FOR i := 1 TO STRLEN(Txt) DO BEGIN
      charint := Txt[i];
      MESSAGE('%1 = %2',Txt[i],charint);
    END;
END;

InMsg.CommitMessage();

CU 50001

OnRun()
IF ISCLEAR(CC2) THEN 
  CREATE(CC2);
IF ISCLEAR(SBA) THEN
  CREATE(SBA);
NullChar[1] := 0;

CC2.AddBusAdapter(SBA, 0);
OutMsg := CC2.CreateoutMessage('Sockets://localhost:6006');

OutS := OutMsg.GetStream();
OutS.WRITE('1st Text');
OutS.WRITE('2nd Text');
OutS.WRITE(NullChar);

OutMsg.Send(0);

but if... it doesn't work. I don't know how null character would be displayed in NAV, but should I get a message off it?

Xypher · 2008-07-25

I'm not sure what you're asking...

Are you referring to the MessageReceived procedure, or in general how NAV would handle a NULL terminating string when displaying?

einsTeIn.NET · 2008-07-25

2nd one. General handling. After some test I think NAV won't display anything. And I think NAV will interpret a zero byte as EOS.

OnRun()
IF ISCLEAR(CC2) THEN
  CREATE(CC2);
IF ISCLEAR(SBA) THEN
  CREATE(SBA);

Text1 := '1st Text';
Text2 := '2nd Text';
Text1[4] := 0;

CC2.AddBusAdapter(SBA, 0);
OutMsg := CC2.CreateoutMessage('Sockets://localhost:6006');

OutS := OutMsg.GetStream();
OutS.WRITE(Text1);
OutS.WRITE(Text2);

OutMsg.Send(0);

If so I can be sure of that NAV creates a stream the external system is able to understand.
If not and there are other reasons why NAV doesn't display the whole stream, I have no chance to proof if the external system receives an understandable stream. In any case not with two NAV clients.

einsTeIn.NET · 2008-09-17

With an outstream variable you will get the null-terminated string / zero byte as EOS if you use

OutS.WRITE

If you use

OutS.WRITETEXT

you won't get it.

[solved]null-terminated stream

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