DDE without controls

Hi

I am trying to write an application in visual basic that talks via a DDE link to our local stock exchange (South African). The problem is that I don't want to link to a VB control like a textbox, label or picturebox. I would prefer to have the information come into a variable, so that I can write it into a database table. Is this possible?

Thanks

Paul

[Ravi Kiran]

DDE being First generation stuff (it is the grand daddy of COM), is designed to work only with controls and its base is windows messaging. OLE has developed more on it and COM is "the" thing , with COM+ and DCOM becoming "the" things ( or have they already become?!!)

In short, if you want the values to come into variables, you should write a Ole (or COM) server and run it on the server side to which you will connect and get the values direclty.

RK

[Lothar Haensler]

you can try to use the functions in DDEML like DdeConnect, DdeGetData and so on.

[jeden]

This may help (sorry but it isn't commented):


public Function GetItemData(DDEInfo as DDEConversation) as DDEConversation
on error GoTo ErrorHandler
Const sProcSig = MODULE_NAME & "GetItemData"
Dim lTransCode as Long
Dim ErrorVal
Dim test
Dim DataSize as Long
Dim StartVal as Long
Dim StringBuffer() as Byte
Dim ReturnString as string
Dim lResult
Dim DataLen

'Create the item string handle
DDEInfo.CurrentItemHandle = DdeCreateStringHandle(DDEInfo.idInst, DDEInfo.CurrentItem, CP_WINANSI)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
DDEInfo.CurrentItemHandle = 0
GetItemData = DDEInfo
Exit Function
End If

If DDEInfo.CurrentItemHandle = 0 then
DDEInfo.CurrentItemHandle = 0
DDEInfo.ErrorStatus = "Unknown error when creating Item Handle in GetItemData in DDEML"
GetItemData = DDEInfo
Exit Function
End If

'Request the data
lResult = DDEML_ClientTransaction(0, 0, DDEInfo.hConv, DDEInfo.CurrentItemHandle, CF_TEXT, XTYP_REQUEST, DDEInfo.TimeOut, 0)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
test = DdeFreeDataHandle(lResult)
DDEInfo.CurrentItemHandle = 0
GetItemData = DDEInfo
Exit Function
End If

' get pointer to data
StartVal = DdeAccessData(lResult, DataSize)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
test = DdeFreeDataHandle(lResult)
DDEInfo.CurrentItemHandle = 0
GetItemData = DDEInfo
Exit Function
End If

StringBuffer = Space$(256)
DataLen = DdeGetData(lResult, StringBuffer(0), DataSize, 0)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeUnaccessData(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
test = DdeFreeDataHandle(lResult)
DDEInfo.CurrentItemHandle = 0
GetItemData = DDEInfo
Exit Function
End If

ReturnString = StrConv(StringBuffer, vbUnicode)
DDEInfo.CurrentItemData = Left$(ReturnString, DataLen)

test = DdeUnaccessData(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
test = DdeFreeDataHandle(lResult)

' Assign value of item name
DDEInfo.ErrorStatus = ""
GetItemData = DDEInfo
Exit Function

ErrorHandler:
With Err
sErrorDescription = "error '" & .Number & " " & .Description & "' occurred in " _
& sProcSig & IIf(Erl <> 0, " at line " & CStr(Erl) & ".", ".")
End With
test = DdeUnaccessData(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
test = DdeFreeDataHandle(lResult)

DDEInfo.ErrorStatus = sErrorDescription
GetItemData = DDEInfo
Exit Function
End Function

public Function PutItemData(DDEInfo as DDEConversation) as DDEConversation
on error GoTo ErrorHandler
Const sProcSig = MODULE_NAME & "PutItemData"
Dim test
Dim ErrorVal
Dim lResult

DDEInfo.CurrentItemHandle = DdeCreateStringHandle(DDEInfo.idInst, DDEInfo.CurrentItem, CP_WINANSI)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
DDEInfo.CurrentItemHandle = 0
PutItemData = DDEInfo
Exit Function
End If

' Poke the data
lResult = DDEML_ClientTransaction(Format(DDEInfo.CurrentItemData), len(DDEInfo.CurrentItemData) + 1, DDEInfo.hConv, DDEInfo.CurrentItemHandle, CF_TEXT, XTYP_POKE, DDEInfo.TimeOut, 0)
ErrorVal = DdeGetLastError(DDEInfo.idInst)
If ErrorVal <> DMLERR_NO_ERROR then
DDEInfo.ErrorStatus = DisplayDDEError(ErrorVal).ErrorStatus
If Left(DDEInfo.ErrorStatus, 5) <> "error" then
DDEInfo.ErrorStatus = DDEInfo.ErrorStatus + " When creating SERVERHANDLE in InitDDE(DDEML.BAS)"
End If
test = DdeFreeDataHandle(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
DDEInfo.CurrentItemHandle = 0
PutItemData = DDEInfo
Exit Function
End If


test = DdeFreeDataHandle(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)

DDEInfo.ErrorStatus = ""
PutItemData = DDEInfo
Exit Function

ErrorHandler:
With Err
sErrorDescription = "error '" & .Number & " " & .Description & "' occurred in " _
& sProcSig & IIf(Erl <> 0, " at line " & CStr(Erl) & ".", ".")
End With
test = DdeFreeDataHandle(lResult)
test = DdeFreeStringHandle(DDEInfo.idInst, DDEInfo.CurrentItemHandle)
DDEInfo.ErrorStatus = sErrorDescription
PutItemData = DDEInfo
Exit Function
End Function


This is my own type:

public Type DDEConversation
ServerName as string
ServerHandle as Long
TopicName as string
TopicHandle as Long
idInst as Long
hConv as Long
CurrentItem as string
CurrentItemHandle as Long
CurrentItemData as string
ErrorStatus as string
TimeOut as Integer
End Type





Contact me if you want more info - am trying to do a DDE Monitor prog at the moment and it's a complete *****.

If you have any decent info on DDE stuff, I'd appreciate a copy please? All I can find is the standard stuff on the MS site (http://msdn.microsoft.com/isapi/msdn...emlib_97ub.htm) and that is all about doing it in C++

Regards,

Jon

[Cart Wang]

I am very grate to saw your article,but i have some questions ,wish your help.
1.Can you give me a simply Sample about the two functions (GetItemData and PutItemData)
2.I can not find the declare of "DDEML_ClientTransaction",why and where can I get the function?

Thank you very much

Cart Wang

[Cimperiali]

I am not an expert of this, but maybe Api guide can help you with dde.
Have a look if following code can help you:


'This application shows you how to use DDE to create a better PrevInstance-function.
'Compile this sample and start it two times
'The first instance minimizes itself and when the second instance is started, it will
'send a message to the first instance to maximize itself.

'in a module
public Const VBServerName = "TestServer"
public Const VBTopicName = "SHOW_YOUR_MAIN_WINDOW"
public Const XCLASS_BOOL = &H1000
public Const XTYPF_NOBLOCK = &H2 ' CBR_BLOCK will not work
public Const XTYP_CONNECT = &H60 Or XCLASS_BOOL Or XTYPF_NOBLOCK
public Const CP_WINANSI = 1004 ' default codepage for windows & old DDE convs.
public Const SW_RESTORE = 9
public Const DDE_FACK = &H8000
public Const XCLASS_FLAGS = &H4000
public Const XTYP_EXECUTE = &H50 Or XCLASS_FLAGS
public Const DNS_REGISTER = &H1
public Const DNS_UNREGISTER = &H2
public Declare Function DdeInitialize Lib "user32" Alias "DdeInitializeA" (pidInst as Long, byval pfnCallback as Long, byval afCmd as Long, byval ulRes as Long) as Integer
public Declare Function DdeCreateStringHandle Lib "user32" Alias "DdeCreateStringHandleA" (byval idInst as Long, byval psz as string, byval iCodePage as Long) as Long
public Declare Function DdeConnect Lib "user32" (byval idInst as Long, byval hszService as Long, byval hszTopic as Long, pCC as Any) as Long
public Declare Function DdeNameService Lib "user32" (byval idInst as Long, byval hsz1 as Long, byval hsz2 as Long, byval afCmd as Long) as Long
public Declare Function DdeFreeStringHandle Lib "user32" (byval idInst as Long, byval hsz as Long) as Long
public Declare Function DdeQueryString Lib "user32" Alias "DdeQueryStringA" (byval idInst as Long, byval hsz as Long, byval psz as string, byval cchMax as Long, byval iCodePage as Long) as Long
public Declare Function DdeUninitialize Lib "user32" (byval idInst as Long) as Long
Function DdeCllback(byval uType as Long, byval uFmt as Long, byval hConv as Long, byval hszTopic as Long, byval hszItem as Long, byval hData as Long, byval dwData1 as Long, byval dwData2 as Long) as Long
DdeCllback = Form1.AppDdeCallback(uType, uFmt, hConv, hszTopic, hszItem, hData, dwData1, dwData2)
End Function
'in a form
Dim isRun as Boolean, idInst as Long, hszVBServer as Long, hszVBTopic as Long
Dim hconvVBServer as Long, dderesult as Long
private Sub Form_Load()
'KPD-Team 2000
'URL: http://www.allapi.net/
'E-Mail: [email protected]
If DdeInitialize(idInst, AddressOf DdeCllback, 0, 0) then Exit Sub
hszVBServer = DdeCreateStringHandle(idInst, VBServerName, CP_WINANSI)
hszVBTopic = DdeCreateStringHandle(idInst, VBTopicName, CP_WINANSI)
'try to find the first instance
hconvVBServer = DdeConnect(idInst, hszVBServer, hszVBTopic, byval 0&)
If hconvVBServer then
Unload me
Exit Sub
End If
DdeNameService idInst, hszVBServer, 0, DNS_REGISTER
me.WindowState = vbMinimized
End Sub
private Sub Form_Unload(Cancel as Integer)
DdeFreeStringHandle idInst, hszVBServer
DdeFreeStringHandle idInst, hszVBTopic
'only unregister the DDE server for first instance
If isRun then
If DdeNameService(idInst, hszVBServer, 0, DNS_UNREGISTER) then
MsgBox "in ServiceUnRegister", vbOKOnly, "error"
End If
End If
DdeUninitialize idInst
End Sub
Function AppDdeCallback(byval wType as Long, byval wFmt as Long, byval hConv as Long, byval hszTopic as Long, byval hszItem as Long, byval hData as Long, byval lData1 as Long, byval lData2 as Long) as Long
Dim iCount as Long, Buffers as string, Ret as Long
Select Case wType
Case XTYP_CONNECT
iCount = DdeQueryString(idInst, hszTopic, vbNullString, 0, CP_WINANSI)
Buffers = Space(iCount)
DdeQueryString idInst, hszTopic, Buffers, iCount + 1, CP_WINANSI
If Buffers = VBTopicName then
me.WindowState = vbNormal
'add any code for the first instance have found the second one is launch
Ret = DDE_FACK
End If
AppDdeCallback = Ret
Case XTYP_EXECUTE
AppDdeCallback = Ret
End Select
End Function





Special thanks to Lothar "the Great" Haensler, Tom Archer, Chris Eastwood, TCartwright, Bruno Paris, Dr_Michael
and all the other wonderful people who made and make Codeguru a great place.
Come back soon, you Gurus.

The Rater

[Cart Wang]

Cimperiali:
Thank you very much,beacause of your helps ,I can finished my program.
I have found a good example about DDE how to write server and client at "http://www.planet-source-code.com".It's very good.
Best wish to you

Cart Wang

[Cimperiali]

You're welcome.

Planet source code is a good place to visit for sources...

Have a nice day,

Cesare Imperiali


Special thanks to Lothar "the Great" Haensler, Tom Archer, Chris Eastwood, TCartwright, Bruno Paris, Dr_Michael
and all the other wonderful people who made and make Codeguru a great place.
Come back soon, you Gurus.

The Rater