[SOLVED] Connect to DDE Server

[jbrooksuk]

Hi all,

Is there any way I can connect to a DDE server? I know DDE is dated tech, but it's the only option I have for what I'm attempting to do.

I've found http://permalink.gmane.org/gmane.comp.lib.qt.general/91 but it only works in Qt 3 and I'm too inexperienced to convert it forwards. Any help?

Thanks,
James

[AcerExtensa]

It only Qt dependency is QString. It is very easy to port it to Qt4.

For example, instead of
@command.ascii()@
use
@command.toAscii().data()@

[jbrooksuk]

That's a good start. I've also fixed some other problems by using (LPCSTR) val.utf16() which solved a couple of problems.

That being said, can you see why this wont work?

@DDEComm *cyDesk;
QString result;
cyDesk->ddeConnect("CYDESK", "Data");
cyDesk->ddeExecute("CALL NUMBER", result);@

I always get the following:

@C:\Users\James.Brooks\Desktop\BLUI-BUILD-DBG..\BLUI\ddecomm.cpp:100: error: C2511: 'QString DDEComm::ddeExecute(const QString &,const QString &)' : overloaded member function not found in 'DDEComm'@

[AcerExtensa]

change function declaration in ddecomm.h from
@QString ddeExecute(QString command, QString result); /!< Executa um comando no servidor dde/@
to
@QString ddeExecute(const QString &command, const QString &result) /!< Executa um comando no servidor dde/@

[jbrooksuk]

We're getting closer! Now I made the changes you said about .ascii().data() but I get 'ascii' is not a member of QString.

Has this got something to do with the changes I made earlier?

@hszRequest = DdeCreateStringHandleA(pidInst, (LPCSTR)item.utf16(), CP_WINANSI);@

I added the (LPCSTR)item.utf16() part, which shut some errors up.

So I've tried the following:

@QString DDEComm::ddeExecute(const QString &command, const QString &result)
{
char *commandName = NULL;
strcpy(commandName, (LPCSTR)command.toAscii());
transactionData = DdeCreateDataHandle(pidInst, (LPBYTE) commandName, strlen(commandName), 0, 0L, CF_TEXT, NULL);
DdeClientTransaction((LPBYTE) transactionData, -1, hConv, 0L, 0, XTYP_EXECUTE, 1000, NULL);

QString returnData = ddeRequest(result);

DdeFreeDataHandle(transactionData);

return returnData;

}@

But now I get a hell load of errors:
!http://dl.dropbox.com/u/7323096/QTDDE.PNG!

[AcerExtensa]

Here is patched DDEComm class:

ddecomm.cpp
@#include "ddecomm.h"

DDEComm* DDEComm::_instance = NULL;

DDEComm* DDEComm::instance()
{
if(_instance == NULL)
_instance = new DDEComm();

return _instance;
}

DDEComm::DDEComm()
{
connStatus = false;
callback = NULL;
pidInst = 0;
hConv = 0L;
}

DDEComm::~DDEComm()
{
//Empty
}

bool DDEComm::ddeConnect(const QString &service, const QString &topic)
{
if(callback == NULL)
{
if(DdeInitializeA(&pidInst, NULL, APPCLASS_STANDARD | APPCMD_CLIENTONLY, 0L) != DMLERR_NO_ERROR)
return false;
}
else
{
if(DdeInitializeA(&pidInst, (PFNCALLBACK) callback, APPCLASS_STANDARD | APPCMD_CLIENTONLY | MF_CONV | MF_ERRORS, 0L) != DMLERR_NO_ERROR)
return false;
}

hszService = DdeCreateStringHandleA(pidInst, service.toAscii().data(), CP_WINANSI);
hszTopic = DdeCreateStringHandleA(pidInst, topic.toAscii().data(), CP_WINANSI);
hConv = DdeConnect(pidInst, hszService, hszTopic, NULL);

DdeFreeStringHandle(pidInst, hszService);
DdeFreeStringHandle(pidInst, hszTopic);

if(!hConv)
return false;

connStatus = true;

return true;
}

void DDEComm::ddeDisconnect()
{
DdeDisconnect(hConv);
DdeUninitialize(pidInst);
connStatus = false;
}

void DDEComm::setDDECallback(PFNCALLBACK ddeCallback)
{
callback = ddeCallback;
}

QString DDEComm::ddeRequest(const QString &item)
{
if(!connStatus)
return NULL;

hszRequest = DdeCreateStringHandleA(pidInst, item.toAscii().data(), CP_WINANSI);
recData = DdeClientTransaction(NULL, 0, hConv, hszRequest, CF_TEXT, XTYP_REQUEST, 1000, NULL);
byte = DdeAccessData(recData, &dwLength);

char data = (char) byte;
QString retStr = data;
DdeFreeStringHandle(pidInst, hszRequest);
DdeFreeDataHandle(recData);
return retStr;
}

QString DDEComm::ddeExecute(const QString &command, const QString &result)
{

transactionData = DdeCreateDataHandle(pidInst, (LPBYTE) command.toAscii().data(), command.length(), 0, 0L, CF_TEXT, NULL);
DdeClientTransaction((LPBYTE) transactionData, -1, hConv, 0L, 0, XTYP_EXECUTE, 1000, NULL);

QString returnData = ddeRequest(result);

DdeFreeDataHandle(transactionData);

return returnData;
} @

ddecomm.h
@/*

• ddecomm.h
• Defines the interface for DDE communication class.
• (C) 2005 Insite Comercio e Servicos.
• Author: Rafael Roquetto
• Qt4 patch: AcerExtensa
• Created on 2005-06-03.
• This is GPL software

*/

#ifndef DDECOMM_H
#define DDECOMM_H

#include <windows.h>
#include <QString>

/*!

• Classe singleton que fornece métodos para comunicacao via DDE
  */

class DDEComm
{
public:

static DDEComm* instance(); /*!< retorna um ponteiro para a instancia de DDEComm */

     bool ddeConnect(const QString & service, const QString & topic); /*!< Connecta ao servico DDE, no topico desejado */

void ddeDisconnect(); /!< Desconecta do servico DDE/
void setDDECallback(PFNCALLBACK ddeCallback); /*!< Seta uma funcao de callback a ser chamada na ocorrencia de eventos DDE */

     QString ddeRequest(const QString & item); /*!< Faz um request dde para o item fornecido */
     QString ddeExecute(const QString & command, const QString & result); /*!< Executa um comando no servidor dde*/

protected:
DDEComm();
~DDEComm();

private:
bool connStatus;
PFNCALLBACK callback; //pointer to callback

     HCONV hConv;
     HSZ hszService;
     HSZ hszTopic;
     HDDEDATA recData;
     HDDEDATA transactionData;
     HSZ hszRequest;
     LPDWORD result;
     DWORD dwLength;
     LPBYTE byte;

DWORD pidInst;

static DDEComm *_instance;

};
#endif /DDECOMM_H/ @

[jbrooksuk]

I've updated my sources, yet I'm now getting a lot of LNK errors.

ddecomm.obj:-1: error: LNK2019: unresolved external symbol _DdeFreeStringHandle@8 referenced in function "public: bool __thiscall DDEComm::ddeConnect(class QString const &,class QString const &)" (?ddeConnect@DDEComm@@QAE_NABVQString@@0@Z)
ddecomm.obj:-1: error: LNK2019: unresolved external symbol _DdeCreateStringHandleA@12 referenced in function "public: bool __thiscall DDEComm::ddeConnect(class QString const &,class QString const &)" (?ddeConnect@DDEComm@@QAE_NABVQString@@0@Z)
ddecomm.obj:-1: error: LNK2019: unresolved external symbol _DdeCreateStringHandleA@12 referenced in function "public: bool __thiscall DDEComm::ddeConnect(class QString const &,class QString const &)" (?ddeConnect@DDEComm@@QAE_NABVQString@@0@Z)
ddecomm.obj:-1: error: LNK2019: unresolved external symbol _DdeUninitialize@4 referenced in function "public: void __thiscall DDEComm::ddeDisconnect(void)" (?ddeDisconnect@DDEComm@@QAEXXZ)

... etc

[AcerExtensa]

Add
@#pragma comment(lib,"User32.lib")@
somewhere in header

[jbrooksuk]

Wahey! Thank you very much AcerExtensa :) No errors compiling, however:

@DDEComm *cyDesk;
QString result;
cyDesk->ddeConnect("CYDESK", "Data");
cyDesk->ddeExecute("CALL ###", result);@

Causes my app to crash. Is this is the wrong syntax?

[AcerExtensa]

Your cyDesk ponter is not initialized and points somewhere in the universe... :)

try something like this:

@
#include <QDebug>
#include "ddecomm.h"

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

DDEComm * test = DDEComm::instance();
const QString service = "CYDESK";
const QString topic = "Data";
const QString command = "CALL ###";
QString result;

if(test->ddeConnect(service,topic))
{
qDebug() << "RESULT: " << test->ddeExecute(command,result);
}
else qDebug() << "Can't connect to service";

return a.exec();
}@

[jbrooksuk]

You sir, are awesome! Thank you very, very much :)

[Momergil]

Hi!

I'ld also like to implement something with this lib. Could you please make the editted version public to download?

Thanks very much!

Momergil