VB API translating into VBA

[Marcel]

Hi,

I'm trying to use a Named Pipe in Word2003. I will let Word talks via this
pipe with another application that serves as an pipe server. I have this
working in two other programming laguages Xbasic and PureBasic. Now I want
add VBA to it

The API function (Visual Basic version) doesn't work in VBA and let Word
crash is the following:

Public Declare Function CallNamedPipe Lib "kernel32" Alias "CallNamedPipeA"
_
(ByVal lpNamedPipeName As String, _
ByRef lpInBuffer As Any, _
ByVal nInBufferSize As Long, _
ByRef lpOutBuffer As Any, _
ByVal nOutBufferSize As Long, _
ByRef lpBytesRead As Long, _
ByVal nTimeOut As Long) As Long

When I change all the Longs in Integers and call it as an CallNamedPipeA
version it doesn't crash anymore and the communication does something.

Declare Function CallNamedPipeA Lib "kernel32.dll" ( _
ByVal lpNamedPipeName As String, _
lpInBuffer As Any, _
ByVal nInBufferSize As Integer, _
lpOutBuffer As Any, _
ByVal nOutBufferSize As Integer, _
lpBytesRead As Integer, _
ByVal nTimeOut As Integer) As Integer

Both versions do get a connection to the pipe server which is running at
that moment. The ReadFile() action in the server doesn't return with
success, res = 0. The server does work correct in connection to other
programs.

-------------- start of VBA code -----------

Option Explicit

Private Const pipeName As String = "\\.\pipe\mynamedpipe"
Private Const BUFFSIZE = 1024
Private hpipe As Integer
Private myerror As Integer

Public Const INVALID_HANDLE_VALUE As Integer = -1

Declare Function CallNamedPipeA Lib "kernel32.dll" ( _
ByVal lpNamedPipeName As String, _
lpInBuffer As Any, _
ByVal nInBufferSize As Integer, _
lpOutBuffer As Any, _
ByVal nOutBufferSize As Integer, _
lpBytesRead As Integer, _
ByVal nTimeOut As Integer) As Integer

Public Sub CallAPipe()

Dim res As Integer, cbRead As Integer, numBytes As Integer
Dim lpInBuffer As String
Dim lpOutBuffer As String

lpInBuffer = "Some text from Word."
numBytes = Len(lpInBuffer)
lpOutBuffer = String(BUFFSIZE, 0)

res = CallNamedPipeA(pipeName, lpInBuffer, numBytes, lpOutBuffer, BUFFSIZE,
cbRead, 0)

If res = 0 Then
myerror = Err.LastDllError
MsgBox "Error number " & myerror & Error(myerror), vbOKOnly
Else
MsgBox "Ok"
End If
End Sub

-------------- end of vba code -----

Is there someone who has done this before and can point me in the right
direction with this code? All kind of help with this code is appreciated.


Regards,

Marcel

 

[Tony Jollans]

OK, I'm way out of my depth on this one but from a quick check via Google
to MSDN ..


BOOL CallNamedPipe(
LPCTSTR lpNamedPipeName,
LPVOID lpInBuffer,
DWORD nInBufferSize,
LPVOID lpOutBuffer,
DWORD nOutBufferSize,
LPDWORD lpBytesRead,
DWORD nTimeOut
);



Seems to me that doesn't tie in with the definitions you have. Longs in VBA
are single words so I would guess your lengths are not being read correctly



PipeName - String looks good

The two Buffer pointers - Should probably be btye arrays but strings should
also work I think

The two buffer lengths - doubleword isn't a VBA type - you might need to
frig this

Bytes read and TimeOut also need doublewords which again might need a frig -
(halfword) integers certainly don't seem to fit the bill.



I know nothing of pipes so can't test or do the trial and error for you but
a byte array for the pointer) and/or fixed length strings (for the
doublewords) - which you build and interpret yourself - might be needed for
all of them.


Don't know if any of that's any help, but as nobody else is answering I
thought I'd try.

 

[Marcel]

Thanks for your answer Tony,

Seems to me that doesn't tie in with the definitions you have. Longs in
VBA
are single words so I would guess your lengths are not being read
correctly

I checked and double checked it on the Microsoft Site:
C/CPP l, lp, lpz, handle and long is in VBA long (long integer) 4 bytes,
range: -2.147.483.648 tot 2.147.483.64.
C/CPP int is in VBA Integer 2 bytes, range: -32.768 tot 32.767

IMHO the long is a DWORD and integer is a WORD but there can be a
difference.

PipeName - String looks good

The two Buffer pointers - Should probably be byte arrays but strings
should
also work I think

I've examined this and it can be the problem. The original code example
http://support.microsoft.com/default.aspx?scid=kb;en-us;871044 does mention
a byte array. But unfortunately I didn''t understand what they were doing.
;-)

Another point is that in other examples I never saw a byte array and they
used static string buffers.

I'll check the byte arrays.

The two buffer lengths - doubleword isn't a VBA type - you might need to
frig this

Bytes read and TimeOut also need doublewords which again might need a
frig -
(halfword) integers certainly don't seem to fit the bill.



I know nothing of pipes so can't test or do the trial and error for you
but
a byte array for the pointer) and/or fixed length strings (for the
doublewords) - which you build and interpret yourself - might be needed
for
all of them.

Don't know if any of that's any help, but as nobody else is answering I
thought I'd try.

Thanks Tony, your help is appreciated.

 

[Marcel]

The code example I mentioned was VB .Net. When to use it in Word VBA you
have to keep the next thing in mind:

Caution If you are interfacing with components written in Visual Basic
version 6.0, for example Automation or COM objects, keep in mind that
Integer has a different data width (16 bits) in Visual Basic 6.0. If you are
passing a 16-bit argument to such a component, declare it as Short instead
of Integer in Visual Basic .NET.

Again a step nearer to the solution.

Marcel

 

[Marcel]

The real code I needed is here:

http://support.microsoft.com/default.aspx?scid=kb;en-us;177696

 

[Tony Jollans]

A bit different. Glad you're found a solution though - because I would have
been struggling

I agree l, lp, lpsz etc. are (VBA) longs - it is the DWORDS I think are the
problem. The trouble with some newer APIs is the VB.NET data types - Short
(=VBA Integer), Integer (=VBA Long) and Long (=not in VBA) - I think!

 

[Marcel]

The byte arrays did it.

I can't simply pass a string to the function. I have to put each character
in a byte array.?!?! Pass the array and it works. I got an VBA example from
the recieving side. I build one for the sending side. Now it works. However
I have to do this only for the VBA code. In the other program (Xbasic) I can
simply create a static string array and it works.

 

[Tony Jollans]

I've never completely got to grips with what happens when but it's all to do
with whether or not Unicode strings get converted behind the scenes by VBA.