FAWEB.NET / IO Server - VC6.0 Sample

	SITEMAP PRIVACY JAPANESE

JAPAN	HOME \| Product \| Support \| Knowledge \| Download \| Sales \| Company \| Contact

You are Here : HOME > Product > I/O Server > Visual C/C++ 6.0 Sample

BACK

Visual C/C++ 6.0 DDE Client Sample (DDEML)

It easily explains the method of mounting the DDE client program (Microsoft Visual C/C++ 6.0) that Microsoft Visual Basic 6.0 accesses the I/O Server by using DDEML(DDE Management Library).

This sample project can be downloaded here.

NOTES Our company does neither any operation guarantee nor the support for the sample code and each explanation that has been opened to the public to this site. The function is recommended to be verified enough when used.

	Sample Screen
In this sample, it writes and the function of four is used, a connection to I/O Server, manual read operation, automatic read operation, manual poke operation.

	Initial
Handler and DDE Conection that processes Callback from I/O Server are defined. HDDEDATA CALLBACK UdprocDdeCallback(UINT, UINT, HCONV, HSZ, HSZ, HDDEDATA, DWORD, DWORD); DWORD idInst=0; // hadle to DDE connection XACT *pxact=NULL; CONVCONTEXT CCFilter = { sizeof(CONVCONTEXT), 0, 0, 0, 0L, 0L, { sizeof(SECURITY_QUALITY_OF_SERVICE), SecurityImpersonation, SECURITY_STATIC_TRACKING, TRUE };

DDE Connection

The application name and the topic name of DDE are set, and the DDE connection is executed.

DDE Manual Read Operation

In a synchronous reading by the DDE manual operation link, the return value of the DDEML function reaches the data value.

DDE Poke Operation

The value is written in the specified item name.

DDE automatic read operation

Callback Handler is called by registering the item name in asynchronous reading and I/O Server by DDE automatic a link every time there is a change in the data value.

BOOL UdprocDdeAdvise(CString citemname){

if(pxact == NULL) return false;
	pxact->hszItem = DdeCreateStringHandle(idInst, citemname, 0);
	pxact->hDdeData = 0;
	pxact->wFmt = CF_TEXT;
	pxact->wType = XTYP_ADVSTART; // DDE Advice (dde automation link)

if(!(pxact->ret = (DWORD) DdeClientTransaction(
			(LPBYTE)pxact->hDdeData, 0xFFFFFFFF, 
			pxact->hConv, pxact->hszItem, pxact->wFmt,
			pxact->wType, pxact->ulTimeout,
			(LPDWORD)&pxact->Result))){
		AfxMessageBox("Failed to DdeClientTransaction");
		return true;
	}
	return false;
}

BOOL UdprocDdeAdviseStop(CString citemname){

if(pxact == NULL) return false;
	pxact->hszItem = DdeCreateStringHandle(idInst, citemname, 0);
	pxact->hDdeData = 0;
	pxact->wFmt = CF_TEXT;
	pxact->wType = XTYP_ADVSTOP; // DDE Advice (dde automation link)

if(!(pxact->ret = (DWORD) DdeClientTransaction(
			(LPBYTE)pxact->hDdeData, 0xFFFFFFFF,
			pxact->hConv, pxact->hszItem, pxact->wFmt,
			pxact->wType, pxact->ulTimeout,
			(LPDWORD)&pxact->Result))){
		AfxMessageBox("Failed to DdeClientTransaction");
		return true;
	}
	return false;
}

Callback Handler

This Handler is called every time there is a change in the item value.

HDDEDATA CALLBACK UdprocDdeCallback(UINT wType, UINT wFmt, HCONV hConv,
			HSZ hsz1,HSZ hsz2, HDDEDATA hData,
			DWORD lData1, DWORD lData2){

PTSTR psz;
	DWORD cb;
	CString cstopic, csitem;

switch (wType) {
	case XTYP_REGISTER:
	case XTYP_UNREGISTER:
	case XTYP_DISCONNECT:
	case XTYP_XACT_COMPLETE:
		break;

case XTYP_ADVDATA:
		// GET Topic Name
		cb = (DWORD)DdeQueryString(idInst, hsz1, NULL, 0, 0) + 1;
		psz = (PTSTR)malloc(cb * sizeof(TCHAR));
		DdeQueryString(idInst, hsz1, psz, cb, 0); //ex)psz="PLC1"
		cstopic = psz;
		free(psz);
		// GET Item Name
		cb = (DWORD)DdeQueryString(idInst, hsz2, NULL, 0, 0) + 1;
		psz = (PTSTR)malloc(cb * sizeof(TCHAR));
		DdeQueryString(idInst, hsz2, psz, cb, 0); //ex)psz="D0"
		csitem = psz;
		free(psz);
		if (!hData)
			hData = DdeClientTransaction(NULL, 0L, hConv, hsz2,
					wFmt, XTYP_REQUEST, 1000, NULL);
		if (hData) {
			#define MAXCCH 1024
			cb = DdeGetData(hData, NULL, 0, 0);
			if (!hData || !cb) break;
			if (cb > MAXCCH) { // possibly HUGE object
				psz = (PTSTR)malloc(MAXCCH*sizeof(TCHAR));
				DdeGetData(hData, (PBYTE)psz,
				  (MAXCCH - 46) * sizeof(TCHAR), 0L);
				wsprintf(&psz[MAXCCH - 46],
					TEXT("<---Size=%ld"), cb);
			} else {
				psz = (PTSTR)malloc(cb * sizeof(TCHAR));
				DdeGetData(hData, (LPBYTE)psz, cb, 0L);
			}
			pDlg->UpdateReadValue(psz);
			free(psz);
			DdeFreeDataHandle(hData);
		}
		return((HDDEDATA)DDE_FACK);
		break;
	}
	return 0;
}

	DDE Terminate
Terminate the connection to I/O Server BOOL UdprocDdeDisConnect(void){ if(pxact == NULL) return false; if(!DdeDisconnect(pxact->hConv)){ AfxMessageBox("Failed to DdeDisconnect"); return true; } if(pxact->ret){ DdeFreeDataHandle((HDDEDATA)pxact->ret); pxact->ret = 0L; } free(pxact); pxact = NULL; return false; }

BACK	Copyright © 1998-2006 TAKEBISHI Corporation All rights reserved.

TAKEBISHI Corporation
29 Mamedacho Nishikyogoku Ukyoku Kyoto 615-8501, JAPAN
TEL: +81-75-325-2171 / FAX: +81-75-325-2273 fa-support@takebishi.co.jp