How can I call the app server function from the client?

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2 total messages Started by George Wei Tue, 11 Jul 2000 00:00

#1035

Author: George Wei
Date: Tue, 11 Jul 2000 00:00

34 lines
1515 bytes

I wrote an app server as an ActiveX library by using C++ Builder 5. In this 
library, I have added a Transactional Data Module, then I implemented a 
function as the following codes:

  STDMETHODIMP TMIDASServer::foo(void)
  {
    ...
    if(...)
      return S_OK;
    else
      return E_FAIL;
  }

On the client side, I added a Data Module, then put a DCOMConnection, a 
ClientDataSet into it. I tried to use the following codes to call this server 
function:

  HRESULT hr;
  hr=DataModule1->DCOMConnection1->AppServer.Exec(Function("foo"));
  if(SUCCEEDED(hr))
    ShowMessage("Succeeded.");
  else
    ShowMessage("Failed.");

The problem is: When the server tries to return S_OK, the client can show the 
message correctly; when the server tries to return E_FAIL, the client raises an 
EOleSysErr exception with the message "Unspecified error". What's wrong with my 
codes?
Another question: I can call the server function as above, is there a similar 
function/method in Delphi 5? If it is, how to do that?
Thanks for any help.

Regards,
George

Re: How can I call the app server function from the client?

#977

Author: Stefan
Date: Tue, 25 Jul 2000 00:00

34 lines
1611 bytes

the return value ist ONLY used to appoint success or failure to the calling
process.
to pass a return value you have to define a return-variable on server side.

------Server side ---------------
STDMETHODIMP TAppModul4Impl::GetTable(TVariant* vTableName,
  TVariant* ReturnValue)
{
    .
         // get Data
    .
      // -------------------------------------------------------------------
        // copy Data (TStringList) to Variant
        Variant v = VarArrayCreate(OPENARRAY(int, (0,Data->Count)),
varOleStr);
        for(int i = 0; i < List->Count; i++) {
            v.PutElement( WideString(List->Strings[i]), i);
        }

        // assign v to ReturnValue
        *ReturnValue = v;
        delete Data;
  }
  catch(Exception &e)
  {
    return Error(e.Message.c_str(), IID_IAppModul4);
  }
  return S_OK;
}

------Client side ----------------
Variant Data;
Data = dbCon->AppServer.Exec(Function("GetTable") <<
riant( String( "<TableName")) );

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