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Yes it can. But I can help you only with ATL - don't have a clue how to do it with MFC. The events are in fact standard methods as any other, so you have just to mark the parameter as [out] or [out,retval]. That's all in IDL.
But if you are using ATL, there's a little need to change the generated Fire_OnMyEvent method. Understanding what's going on inside the method is the key to the success 
On beginning there's created a new array of CComVariants. Later on, all parameters are copied(!) to this array. And you need to change exactly this behavior - there are several ways...
What you can use is instead of copying the value, use the already existing variant in an array and turn him to the reference to your out parameter (VT_BYREF flag can be handy). But any other method can be also usefull and working - it's up to you to decide how you want to do it.
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Hi,
I am learner of COM Technology.I have written simple com object.It has 3 methods.I compiled it successfully.But the problem is I have written client program,it is showing errors.
i have included component's .h,_i.c files into client program
CoInitialize(NULL);
CoCreateInstance(..........);
what are the steps to follow to write COM Client program.
yakkalas
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Did you register the COM server to registry? What is the error?
Kuphryn
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hi,
yah registered COM Server to registry.
atlwin.h requires atlbase.h to be included first
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Did you use the ATL wizard?
What is the error yu get?
R.Balachandran
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I have created Arthematic simple object.
in Client program i write like this.
CoInitialize(NULL);
IArthematic *art;
CoCreateInstance(CLSID_Arthematic,NULL,CLSCTX_INPROC_SERVER,IID_Arthematic,reinterpret_cast<void**>&iu);
And when compiling, compiler shows atlwin.h require atlbase to be included first.
I have included Arthematic.h and MyCom_i.c files in my client program.
how can I get out of this and plz tell me how to write client program for a simple object.
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Include the .h file that ATL's MIDL generated and the .h file from of the coclass.
Kuphryn
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Here I have given a sample working code for a COM client
// COMClientDlg.cpp : implementation file
#include "stdafx.h"
#include "COMClient.h"
#include "COMClientDlg.h"
#include "COMServer.h"
#include "COMServer_i.c"
............................
............................
............................
HRESULT hr;
IMessage *msg;
hr = CoInitialize(0);
//initialize COM
if( SUCCEEDED(hr) )
{
hr = CoCreateInstance(
CLSID_Message,
NULL,
CLSCTX_INPROC_SERVER,
IID_IMessage,
(void **)&msg
);
if( SUCCEEDED(hr) )
{
msg->Show();
msg->Release();
}
else
{
AfxMessageBox("Cannot create COM object");
}
CoUninitialize();
//uninitialize COM
}
else
{
AfxMessageBox("Cannot initialize COM");
}
This code worked fine when I tested under an MFC dialog project.
The server was created as a DLL by the ATL wizard. While creating a simple object
the following options were selected.
Threading Model - apartment
Interface - dual
Aggregation - yes
If you still have trouble you can mail your code to me
R.BALACHANDRAN
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You should use #import directive and smart pointers.
It makes everything simple for developing COM client.
For example, if you have COM object named Message then do the following:
#import "Message.tlb" no_namespace
void main()
{
CoInitialize(NULL);
try
{
IMessagePtr pMessage = IMessagePtr(__uuidof(Message));
pMessage->Method();
}
catch(_com_error &e)
{
HRESULT hr = e.Error();
}
CoUninitialize();
}
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the MainFrame Menus of Active Document Server Application is dynamic created ;
so how can i make the container' embed Menu as same as the menu of active document server application ? What can i do it?
please help me ,thanks
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Hello,
Can somebody point me out the differences between the webbrowser control and the internetexplorer object ?
What are the purpose of each one ?
Can you build the same applications with both ? Can they be embedded the same way ?
Is one control offering more features than the other, including non-visual features (like more cookies stuff...) ?
Thanks,
R. LOPES
Just programmer.
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Hi,
I'm a novice in COM so my question is very easy.
I want to crete the COM server (INPROC_SERVER) with method like:
virtual /* [helpstring][id] */ HRESULT STDMETHODCALLTYPE GetStr(
/* [out][in] */ LPSTR lpcszStr) = 0;
STDMETHODIMP CAbc::GetStr(LPSTR lpcszStr)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState())
// TODO: Add your implementation code here
char *mystr="string from COM";
lpcszStr=mystr;
return S_OK;
}
So, is it possible to return the string pointer from COM server?
Yours sincerely,
Alex Bash
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Hi,
I'm a novice too. But I have had the same problem. So maybe I can give you a hint.
As far as I know the best solution is to use the BSTR data type. This is not very complicated. There are only some special functions that you have to use: SysAllocString, SysFreeString, SysStringLen and some other ones. You could do it like this:
IDL:
GetStr([out] BSTR* str)
Method implementation:
STDMETHODIMP CAbc::GetStr(BSTR* str)
{
//Allocate memory for the BSTR
str = SysAllocString("string for COM");
//Check wether allocation was successful
if(str) return S_OK;
else return E_FAIL;
}
And the caller:
...
BSTR myBStr;
HRESULT hr = Abc->GetStr(myBStr);
if(FAILED(hr)) damned();
else
{
//Now you've got the string
//Do with it what ever you want (but don't get rude...)
//You can use it like a LPSTR as far as I know
printf("My String: %s", myBStr); //example
SetDlgItemText(IDC_EDIT, myBStr); //example
//But now it is your responsability to free the memory!
SysFreeString(myBStr);
//That's it
}
...
I hope this was all correct. Try it. It should work.
But maybe someone else can tell you more or correct my posting.
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Remember to pass in the COM interface function an address of BSTR and to dereference the pointer to a BSTR before assignment.
*str = SysAllocString("string for COM");
HRESULT hr = Abc->GetStr(&myBStr);
Kuphryn
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what he says and what u answer..?? oooooooops..
[ It is possible to represent everything in this universe by using 0 and 1 ]
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in an ocx how do i get the hinstance of the container? specifically, if a vb project is using the ocx, how would i get the parent (vb project) hinstance so i may access the resource file in th vb project?
shotgun
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Hi,
I have a sample code in VB that I need to "translate" to VC++.
But I don't know how tu use safearrays.
Here is the VB code :
<br />
Dim pSafeArray As Variant<br />
pSafeArray = pBlock.SafeArray(0)<br />
' Loop through the SafeArray and set value to each pixel<br />
Dim I, J As Integer<br />
For I = 0 To pSize.X - 1<br />
For J = 0 To pSize.Y - 1<br />
pSafeArray(I, J) = I + J<br />
Next J<br />
Next I
pBlock is an object provided by the API I'm using
Could you help me ?
Thx,
Stephane
www.exotk.org
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I'm trying to enumerate OLE and VB Controls of a other process. I've already found the Microsoft article (Q141414) about how to do this by using the IOLEClientSite Interface.
I've already sucessfully "entered" the process using dll injection methods, now I face the problem how to get a pointer to IOLeClientSite without using COleControl::GetClientSite() as described in the mentioned article.
Perhaps there is another method to enumerate controls I'm not aware of?
Thanks
Georg
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 The interface IShellDispatch,has an updated interface named IShellDispatch2.
How to invoke IShellDispatch2 and all the members method.
Swarup
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hello,
i have a problem passing objects in a event function.
i created a com object which listens for incoming tcp/ip connections in the background. the listening can be started by an method which returns immediatly. then a thread is created by the com object, waiting for incoming connections, and executing an event, to inform the client.
because the event is fired from a different thread, i marshalled the event source objects in the advise function and unmarshal when firing the event. this works fine as long as i pass only simple parameters like a long.
but i want to pass an com object which i created in the receiving thread to the client. for example an object which holds information about the established connection.
but when i fire the event, the object pointer is passed to the event function. if i call methods on this event in the client, i get an error, that the esp was not saved properly across a function call. why is that? and what can i do about this? maybe i have to marshal the transmitted objects pointer in some way, but i do not know how. do i have to marshal the object in a stream, transmit the stream, and unmarshal on the other side? but would make no difference, i think, because then i have to transmit the stream object, should cause the same error.
all is running inproc and the event source interface has the oleautomation attribute for standard marshalling.
then i changed the event to a dispinterface. fired the event by the invoke method passing the object as an variant parameter. the test with vbscript host was successful. there i can access the transmitted object. i think the invoke method does something with the object.
how can i get this working with an IUnknown derieved event source interface?
many thanks for help
enrico
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The usual mistake is a declaration of _cdecl-eventfunction instead of the _stdcall one.
SINK_ENTRY_EX(1, IID__IXXXXEvents, 1, voidGotEvent)<br />
...<br />
END_SINK_MAP()<br />
...<br />
HRESULT voidGotEvent(long Message)<br />
{<br />
...<br />
}
With best wishes,
Vita
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I am designing OPC Server(ole for process control) custom interface using VC++6.0
com/dcom.i have to design a EXE server component.
My requirement is to implement as many as 8 interfaces in a single class.i am
using ATL COM APPwizard-exe server.in it when i am trying to implement interfaces
through insertmenu->NEW ATLobject it is allowing only one interface at a timeto a
class, but when i am repeating the same process again it is creating separate class &
not allowing to give the same class name.
Here my doubt is can i give more than one interface to a class going through ATL
COM APPwizard,if possible HOW ?
I too tried through Insert->New Class &inserted a new Atlclass,there i was able to
give at best 3 interfaces but it won't satisfied my requirement.
satish kumar silla
Larsen& Tubro Ltd
mumbai
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Add new interfaces to the coclass via IDL. Compile the IDL file.
Kuphryn
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I am designing OPC Server(ole for process control) custom interface using VC++6.0
com/dcom.i have to design a EXE server component.
My requirement is to implement as many as 8 interfaces in a single class.i am
using ATL COM APPwizard-exe server.in it when i am trying to implement interfaces
through insertmenu->NEW ATLobject it is allowing only one interface at a timeto a
class, but when i am repeating the same process again it is creating separate class &
not allowing to give the same class name.
Here my doubt is can i give more than one interface to a class going through ATL
COM APPwizard,if possible HOW ?
I too tried through Insert->New Class &inserted a new Atlclass,there i was able to
give at best 3 interfaces but it won't satisfied my requirement.
satish kumar silla
Larsen& Tubro
mumbai
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Hi,
I want to load HTML code from file to MSHTML :
<br />
HGLOBAL hMemLoad = GlobalAlloc(GPTR,(strlen(pBuffer)+1)*2);<br />
WCHAR* pwBuff = (WCHAR*) GlobalLock(hMemLoad);<br />
MultiByteToWideChar(CP_ACP,MB_COMPOSITE,pBuffer,-1,pwBuff,strlen(pBuffer));<br />
GlobalUnlock(hMemLoad);<br />
<br />
HRESULT hRes = 0;<br />
IStream *pStreamLoad; <br />
CreateStreamOnHGlobal(hMemLoad,FALSE,&pStreamLoad);<br />
<br />
IPersistStreamInit *pStreamInitLoad;<br />
hRes = pHtmlDoc2->QueryInterface(IID_IPersistStreamInit,(LPVOID*) &pStreamInitLoad);<br />
<br />
pStreamInitLoad->InitNew(); <br />
pStreamInitLoad->Load(pStreamLoad);<br />
pStreamInitLoad->Release();<br />
<br />
pStreamLoad->Release();<br />
<br />
GlobalFree(hMemLoad);<br />
But, when I try :
<br />
IHTMLDocument3 *pIHD3;<br />
hRes = pHtmlDoc2->QueryInterface(IID_IHTMLDocument3,(LPVOID*) &pIHD3);<br />
IHTMLElementCollection *pColl;<br />
pIHD3->getElementsByTagName(L"a",&pColl);<br />
long l;<br />
pColl->get_length(&l);<br />
<code><br />
<br />
to get number of items, I getting 0. ;-(.<br />
<br />
Can somebody tell me what I do wrong ?<br />
Thanks, <br />
Luda
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