Direct Interface Error

[Frank W. Kelley]

In working on converting PB8 code (using COM Dispatch calls) to PB9 (and COM Direct calls), we've run into an interesting problem. We're calling an out-of-process COM server in a program called Unfair Advantage. The interface includes a method called GetFirstMarketProfile that returns a long value. While calling this method works perfectly for the dispatch interface, it fails using the direct interface under PB9.

After spending some time with the help file, we developed the following test code:

#COMPILE EXE
#DIM ALL

#INCLUDE "D:\_AMR\QBH\QB3_source\Include\UAPB.inc"  ' Object library

FUNCTION PBMAIN () AS LONG
   LOCAL ret&

   LOCAL oUA AS IAPI2
   oUA = NEWCOM $PROGID_UA_API2API2
   
   IF ISOBJECT(oUA) AND ISFALSE ERR THEN
      oUA.IsStock = 0
      ret& = oUA.GetFirstMarketProfile

      MSGBOX OBJRESULT$
      oUA.HoldUAOpenOnClose = 0
      oUA = NOTHING
   ELSE
      MSGBOX "Unable to open Unfair Advantage."
   END IF

END FUNCTION

From the object library:

' Generated by: PowerBASIC COM Browser v.2.00.0058
' DateTime    : 8/26/2008 at 9:20 PM
' ------------------------------------------------
' Library Name: UA
' Library File: C:\UA\uad.exe
' Description : CSI's Unfair Advantage® Library
' GUID : {6F2F99A0-6600-11D3-B331-525400E8C92C}
' LCID : 0
' Version : 1.0

' Version Dependant ProgID's
$PROGID_UA_API2API2 = "Ua.API2"
$PROGID_UA_UAScriptCallBackObjectUAScriptCallBackObject = "Ua.UAScriptCallBackObject"

' Class Indentifiers
$CLSID_UA_API2 = GUID$("{6F2F99A3-6600-11D3-B331-525400E8C92C}")
$CLSID_UA_UAScriptCallBackObject = GUID$("{A7120BAF-D87E-4949-93A0-53BB63F4D528}")

' Interface Indentifiers
$IID_UA_IAPI2 = GUID$("{6F2F99A1-6600-11D3-B331-525400E8C92C}")
$IID_UA_IUAScriptCallBackObject = GUID$("{F9EBB714-9476-4EA4-8F4C-1CB041E57708}")

' Interface Name  : IAPI2
' Description     : Dispatch interface for API2 Object
' ClassID         : $CLSID_UA_API2
INTERFACE IAPI2 $IID_UA_IAPI2 
    INHERIT IDISPATCH

    PROPERTY GET MarketNumber <1> () AS LONG
    PROPERTY SET MarketNumber <1> (BYVAL Value AS LONG)
    PROPERTY GET MarketSymbol <2> () AS STRING 
    ' < - snip - >         
    METHOD GetFirstMarketProfile <30> () AS LONG

OBJRESULT$ returns "Incorrect function". Since we know the method is available in the interface, we're at a loss as to why it cannot be accessed using the direct method. Any help is appreciated.

[José Roca]

The error code for this message is 1 (%ERROR_INVALID_FUNCTION). My guess is that this is the result returned by the method, not an error code.

You told me by email that my browser generated the following definition

  METHOD GetNextMarketProfile <31> ( _             ' VTable offset = 168
  )                                                ' void

My guess is that the type library for this component is buggy.

Try it changing the declaration to:

METHOD GetFirstMarketProfile <30> (BYREF nProfile AS LONG)

[Frank W. Kelley]

Thanks, José, but I'm still getting the "Incorrect function" error even with the change you suggested.

The example provided with the Unfair Advantage COM API document is VB code, and I thought something might have gotten lost in translation (although the VB code appears to be straightforward). The PB code does work well when using the dispatch interface. Also, we can set and get properties using the direct method in PB (no error is produced); only when calling a method do we run into problems.

Thanks again for your help on this problem and all the other help you provide for the PB community.