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Re: C++ COM EventHandler: How to catch COM events from Delphi COM Server / VC6

ipforce2-Apr-09 6:08

2-Apr-09 6:08

Hi,

thank you for your quick answer. I've read this article before, and I've implemented a Event Sink in that way, how it was described in Microsofts AtlEvent[^] Example. One another good article I've found in another site Dispinterface vs. Events and Runtime Sinks[^] has brought me on the idea with the special MT CoInitialize flags.

But the reality is, if I follow the steps to create the event handler as shown in the MS or guru example, everything goes o.k. (Connection is built, every function gives S_OK). Server is found, etc., even DispEventAdvise gives S_OK.

- But I didn't receive any event - muahhh Sigh | :sigh:

The events are really fired from the source, because some Delphi Demo Client App shows me the events.

So I came onto the idea that DELPI COM is something special. Do you know a method to deep TRACE the COM event handling ?

<br />
1. Create a new class derived from IDispEventImpl. <br />
      class CSinkObj : public IDispEventImpl<IDC_OBJ, CSinkObj><br />
      {<br />
         ...<br />
      }<br />
<br />
2. Specify the source interface ID, ...<br />
<br />
      class CSinkObj : public IDispEventImpl<IDC_OBJ, CSinkObj,<br />
         &DIID__EventSink, // Source interface GUID.<br />
         &LIBID_COMOBJLib, // typelib ID containing source interface.<br />
         1,                // Major version # of LIBID_COMOBJLib.<br />
         0>                // Minor version # of LIBID_COMOBJLib.<br />
      {<br />
         ...<br />
      }<br />
<br />
3. Add a sink map ... SINK_ENTRY():<br />
<br />
      class CSinkObj : public IDispEventImpl<IDC_OBJ, CSinkObj,<br />
                              &DIID__EventSink, &LIBID_COMOBJLib, 1, 0><br />
      {<br />
      public:<br />
         BEGIN_SINK_MAP(CSinkObj)<br />
            SINK_ENTRY_EX(IDC_SRCOBJ, DIID__EventSink, 1, OnTick)<br />
         END_SINK_MAP()<br />
         ...<br />
      }<br />
<br />
4. Add event handler methods to your class ( __stdcall calling convention):<br />
<br />
      class CSinkObj : public IDispEventImpl<IDC_SRCOBJ, CSinkObj3><br />
      {<br />
      public:<br />
         BEGIN_SINK_MAP(CSinkObj)<br />
            SINK_ENTRY(IDC_SRCOBJ, 1 , OnTick)<br />
         END_SINK_MAP()<br />
<br />
         // event handler for event defined in idl as<br />
         // [id(1)] HRESULT Tick([in] long tckcnt);<br />
         HRESULT __stdcall OnTick(long tickcnt)<br />
         {<br />
            ATLTRACE("CSinkObj::OnTick\n");<br />
            return S_OK;<br />
         }<br />
         ...<br />
      }<br />
<br />
5. Connect the sink to the COM object :<br />
      pSinkObj->DispEventAdvise(pUnk);<br />
<br />
6. Disconnect the sink by calling DispEventUnadvise():<br />
<br />
      pSinkObj->DispEventUnadvise(pUnk);<br />

BR,
Andreas

Re: C++ COM EventHandler: How to catch COM events from Delphi COM Server / VC6

ipforce2-Apr-09 6:59

ipforce

2-Apr-09 6:59

I've found my fault by my self, using the Rubber Duck method below (thanks your help Jonathan Laugh | :laugh:

):

We called it the Rubber Duck method of debugging. It goes like this: 1) Beg, borrow, steal, buy, fabricate or otherwise obtain a rubber duck (bathtub variety) 2) Place rubber duck on desk and inform it you are just going to go over some code with it, if that’s all right. 3) Explain to the duck what you code is supposed to do, and then go into detail and explain things line by line 4) At some point you will tell the duck what you are doing next and then realise that that is not in fact what you are actually doing. The duck will sit there serenely, happy in the knowledge that it has helped you on your way. Works every time. Actually, if you don’t have a rubber duck you could at a pinch ask a fellow programmer or engineer to sit in.

My fault was, that I have used the VS generated UUIDs for coclass & its library, because I thought, they must be different from the source's TLB, because I took a specialization from the servers interface.

But if I use the server IDs it works. Roll eyes | :rolleyes:

Happy greetings,
Andreas

Updating Resource

sumedh_code30-Mar-09 0:55

sumedh_code

30-Mar-09 0:55

I am having a text file as a resource in my project. Now when i run the exe, i want to read a text file from anywhere on the file system and update my resource. I have tried UpdateResource, it succeeds, but does not reflect the changes in the resource file of my binary.I have used EndUpdateResource also. Please help me out....

Access Denied in VC++ COM

RevathiRamakumar30-Mar-09 0:20

RevathiRamakumar

30-Mar-09 0:20

Hi all...I have a server Component which is a inprocess exe and a dialog based client... Server has 3 methods ..One method returning CPU usuage , other method returning the memory usuage and the third method just returns a BSTR String... In client code ,when I try to call the third method(returns the BSTR srting) I get Access Denied error.. How can I overcome this issue... Confused | :confused:

Thank u..

Here's my sample code..(Client).

CoInitialize(NULL);
HRESULT hr = NULL,hr1=NULL;
IGetStatus* pGetStatus;

hr=CoCreateInstance(CLSID_GetStatus,NULL,CLSCTX_LOCAL_SERVER,IID_IGetStatus,(void **)&pGetStatus);

if(SUCCEEDED(hr))
{
try
{
_bstr_t str1 ;
str1 = pGetStatus->GetBeat();
char* Text = _com_util::ConvertBSTRToString(str1);
AfxMessageBox(Text);
::SysFreeString(str1);
UINT CPU_Info = pGetStatus->Get_CPU();
int Memory_Info = pGetStatus->Get_Memory();
}
catch(_com_error e)
{
AfxMessageBox(e.ErrorMessage(),MB_ICONSTOP);
}
}