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ASP calling VB Dll

Posted on 2003-03-13
Medium Priority
Last Modified: 2010-05-01
I have a VB DLL that I call from my ASP page.  The DLL is really just a shell around another Dll.  I just created my own functions that puts a little business logic in the DLL instead of doing it in the ASP page.

My problem is this:

I can call my dll from a quick vb app I wrote to test it and it works fine.  When I try to call it from Asp page I get some wierd results.

Here is the basis of my Dll that I am calling

Private Declare Function GetDevice _
   Lib "MYDLL.Dll" (byVal ID as Integer) as Long

Public Function C_GetDevice(ByVal GetId as Integer) as Long
    C_GetDevice = GetDevice(GetId)
End Function

From VB I do this:

Dim oDll as Object
Set oDll = CreateObject("CDUSB.MyDll")

rtn = oDll.C_GetDevice(0)

I receive 18481 back

From ASP I do this:
Dim oDLL
Set oDll = server.createobject("CDUSB.MyDll")

rtn = oDll.C_GetDevice(0)

I receive back -437385700

Question by:edfrazier

Assisted Solution

Skirde earned 150 total points
ID: 8131384
It's been a while since I did this but if I remember right ASP pages don't understand datatypes other than variant so it may be a type mismatch.

good luck
LVL 10

Assisted Solution

aeklund earned 150 total points
ID: 8131639
I think the problem lies with your function "GetDevice" inside mydll.dll.

I recreated your three files, mydll.dll and cdusb.dll and an asp page...  I cannot see what your function does, so I simulated it and have it just return a static number "18481" and I get the same results when I call it from vb, or asp.
LVL 44

Accepted Solution

Arthur_Wood earned 150 total points
ID: 8133103
what your GetDevice is returning is called a Device HANDLE, and that is essentially a memory location, which may be 1) different each time the code is executed, and especially if run on differwent machines, or platforms (VB IDE vs WebServer), and 2) is a Long integer, which may or may not have the High bit set (which is the bit which controls + or -)

The fact that the two calls are returning different values is not so important as whether they ALWAYS RETURN the SAME value (one value when running from the VB IDE- but the SAME value each time it runs in this mode) and a Different value(perhaps, buy again the SAME value) when ruuning on the WebServer, from the ASP page.


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LVL 26

Assisted Solution

EDDYKT earned 150 total points
ID: 8135903
May be change all interger to long


Private Declare Function GetDevice _
  Lib "MYDLL.Dll" (byVal ID as long) as Long



Expert Comment

ID: 9056360
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Author Comment

ID: 9404699
This was never resolved, thanks for the help

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