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Hi!
How do I do start, which method do I use if I want an already open Windows file Open/Save dialog to change path?
Thanks!
/Jii
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Object A was configged as "Requer Transaction" property and Object B(Actually is a databass access object to oracle and use ado to access to the datasource) was configged as "Supported Transaction" one.now A will invoke B and B must run in the Transaction context.is that practical and how to write the implement code of enlist the two transaction? thank you.
Scratch
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Hi, i appologise if this question has been asked be before but its got me stummped, i need to overwrite one of the function pointers in a COM interface, i dont have access to the COM source nor can i modify it, i simply need to overwrite the pointer, i keep getting access violations.??
Goes something like this.
IInterface * MyInterface= MakeInterface();
unsigned * vTbl = ((unsigned**)MyInterface)[0];
vTbl[THE_FUNCTION_INDEX] = NewFunction;
Hope that gives you the idea of what i want, kinda like hooking a COM interface, i have yet to find an easy/any soloution like simply overwriting the functions pointer.
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Implement interface you want to overwright.
1. You can use ATL to implement Interface.
2. Or see this example:
#include "stdafx.h"
#include "windows.h"
#import "testObj.dll"
#include "comdef.h"
class MyNew: public ::TESTOBJLib::ItestPtr
{
public:
MyNew()
{
::CoInitialize(0);
::TESTOBJLib::ItestPtr p;
(*((::TESTOBJLib::ItestPtr*)this)).CreateInstance(L"TestObj.test");
}
~MyNew()
{
this->Release();
::CoUninitialize();
}
HRESULT In( _bstr_t wsIn )
{
(*((::TESTOBJLib::ItestPtr*)this))->In(wsIn);
return S_OK;
};
HRESULT f()
{
::OutputDebugString("this my function.");
return S_OK;
}
};
int main(int argc, char* argv[])
{
MyNew p;
p.f();
p.In("test");
return 0;
}
soptest
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Ok forgive me, im not familiar "yet", with COM and ATL etc, but from what i can gather that would require implementing every method and making it call the base (default) method for all methods i want to keep, unfortunatly the interfaces are pretty big reaching into the hundreds of methods and implementing each method to call its base method would be very time consuming.
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COM supports two kinds of object orientation over binary components with C++. They are Containment and Aggregation.
Containment: This is traditional C++ wrapping up style where the new CoClass will implement the desired interface and internally use the Binary component to perform the operations.
Aggregation: The new CoClass will delegate the implemented interafce requests to the binary component and any request to the CoClass from binary component will be delegated back. This is a kinda tricky thing and has got restrictions. Like, the component being aggregated should be an In-Proc Server and should support component aggregation.
Advantage of Containment Over Aggregation: It doesnt have any restrictions.
Advantage of Aggregation Over Containment: You dont have to implement all interface methods by youself in the component. You'll just delegate, this will be handy if interface has lot of methods.
Check out COM books for further details.
Thanks,
Ramu
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You are probably German. I think only Germans use the word "overwrite" like this. In the past I have tried to explain that the correct English word probably is "override" but Germans insist they are correct and I am mistaken.
Perhaps you really want to override the function pointer, and if so then perhaps you will get help if you state the problem that way.
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Hi All,
ATL forces the developer to implement the Call Factory (IClassFactory) and the Interface(s) implementation as part of the same C++ class (done through their template classes).
My question is: Is it possible to actually implement them (like in the old days) as seperate classes? This of course while using ATL. If so, what is the trick.
Any help is greatly appreciated.
Regards,
...Marc
marc.bednar@cactus.ca
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Hi all,
I've been digging through tons of documentation but as of yet, I still haven't found an answer to a simple question.
When an MFC ActiveX control fires an event, does it return immediately or does it return only after the container's event handler is finished?
Thanks!
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Im doing a simple non-MFC application.. I need to convert an ASCII string into an OLECHAR array. I want to pass my string into a SysAllocString(); function call like this:
<br />
char string[] = "ASCII STRING";<br />
(t+f)->str = SysAllocString(string);<br />
Of course this doesnt work because, SysAllocString is expecting an OLECHAR FAR*. The function works fine when I do:
<br />
(t+f)->str = SysAllocString(OLESTR("Test String"));<br />
Im actually passing in an array of UDTypes with variable length strings from VB and populating each element of the array / structure.
Im not very familiar with this whole ATL/COM string stuff.. =) Ill be honest, Im a C programmer, so Im out of my element. What can I do.. Please Help.
Ryan Baillargeon
Software Specialist
Fuel Cell Technologies Inc.
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If you #include <atlbase.h> & <atlconv.h>, you can use the ATL string conversion macros. These convert strings 'on-the-fly':
const char* s;
BSTR s = ::SysAllocString(A2COLE(s));
LPCTSTR ts;
BSTR s = ::SysAllocString(T2COLE(ts));
They 'do the right' thing wrt conversion to/from Unicode & ASCII & use the stack for temporary string allocation (so are reasonably efficient and deallocate the temporaries automatically).
Alternatively, the CComBSTR or _bstr_t classes seem to work pretty well (I tend to use _bstr_t because it's got char* & wchar_t* extraction operators). The following code should properly allocate a BSTR for use in a C struct
struct {
....
BSTR bs;
....
} thing;
char* s;
thing.bs = CComBSTR(s).Detach();
Just remember to make sure that the BSTR is properly deallocated - using SysFreeString if you do it yourself. For this reason, you'd be better having a CComBSTR in your struct if that's at all practical, as the CComBSTR will deallocate the BSTR in it's destructor.
HTH
Stuart Dootson
'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p'
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Just take care of the conversion macros like A2W, W2A, A2COLE, etc.. for 2 reasons:
1) They dynamically allocate memory ON THE STACK. This is good because it is fast and memory autmatically gets freed when the stack goes out of scope. However, there are memory limitations, so big strings could cause nasty things....
2) CComBSTR (or any other BSTR strings) support EMBEDDED NULLs. For those who do not know what embedded nulls are - basically, a BSTR could be: "Hello\0World" (notice the 0 in the middle.). When a BSTR is counted using SysStringLen(), the proper lenght is taken (SysAllocString stores the lenght of the string). However, if strlenW is used, it will stop after the "Hello" and not count the "World" part. A2W, W2A, A2COLE etc.. use strlenW to get the lenght of the string and not SysStringLen... this causes a converted string to be truncated when it encounters and embedded NULL.
Jeremy.
"Hey man, Taliban, Tali me Banana."
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I have a dialog resource within a COM object and have added a thirdparty ActiveX control to the dialog box.
During execution, while loading the dialog resource I get the following error message..
"Dialog has OLE controls, but not matching DLGINIT resource"
I checked the .rc file and there is DLGINIT resource defined.
Any clue. Thanks
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Hi,
I have seen and replied to an earlier post of yours.
I think there is no problem in your programming and
the fault lies with the ActiveX control.
The ActiveX control should support specific interfaces
for saving information during design time, so as to enable
the Application to load it during runtime.
I think that your AciveX control is having specific
Run-time validation which is not fullfilled by the
default behavior of Dialog start up.(ActiveX Control Support).
What you need to do now is create the Active X control at
runtime and then place it in the specific position
on the dialog programmatically.
Look into the documentation for the ActiveX control.
During the creation you can pass the specific liscensing requirement.
PS: Can you tell me what control is it ?
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It's MSChart Control.
Hope I mentioned that, The dialog resource is in a COM DLL. The control loads properly in an EXE just fine.
Thanks.
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I pass a SAFEARRAY through a Variant in VB.
Now i have the Variant and i don't know how to extract the SAFEARRAY from it.
rechi
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STDMETHODIMPL MyCOMClass::VBMethod(VARIANT * vt)
{
SAFEARRAY *psa;
if(vt == NULL)
return E_POINTER;
//assuming safearray consists BSTR. if not change to appropriate sa datatype
if(vt->vt != VT_BSTR | VT_ARRAY)
{
return E_INVALIDARG;
}
psa = vt->parray;
ATLASSERT(psa != NULL);
//use safe array here
return S_OK;
}
Hth,
Ramu
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This is more of a configuration question.
I have a firewall between me and a DCOM component that is only letting allowing DCOM traffic (or more specifically I guess RPC traffic) through ports 135 and 40000-40001.
I have followed instructions on how to achieve this from such entertaining articles such as "Using Distributed COM with Firewalls" (from MSDN) but to no avail. My component is still trying to establish a connection through any random port it likes.
Although I'm well versed in details of TCP and the like I am a bit lost as to how to diagnose the problem here.
A nod in the right direction would really be appreciated. Typically, most of the article I'm coming across are knee deep in most details but then skip quickly over the art of configuring the security aspects.
TIA
JBoy
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I made a COM exe that i create from other applications, but when i close the application that created it, it goes away. How can i make it so that the COM exe stays even when the program that created it closes?
Thanks![Rose | [Rose]](https://www.codeproject.com/script/Forums/Images/rose.gif)
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Hi Shadow,
That's the correct implementation, it should go away when the application that creates it
goes away! But if you are looking for a quick and dirty way to do that, look at CExeModule::MonitorShutdown() or comment the SetEvent call in CExeModule::Unlock. I assumed you are using ATL. But why do you want
your server to remain?
Last Article:
Client/Server Socket class
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I added a bool (bOKToShutdown) that gets set to true only if the user closes the app (from a tray icon).
void CExeModule::MonitorShutdown()
{
while (1)
{
WaitForSingleObject(hEventShutdown, INFINITE);
DWORD dwWait=0;
do
{
bActivity = false;
dwWait = WaitForSingleObject(hEventShutdown, dwTimeOut);
} while (dwWait == WAIT_OBJECT_0);
if (!bActivity && m_nLockCnt == 0 && bOKToShutDown)
{
#if _WIN32_WINNT >= 0x0400 & defined(_ATL_FREE_THREADED)
CoSuspendClassObjects();
if (!bActivity && m_nLockCnt == 0)
#endif
break;
}
}
CloseHandle(hEventShutdown);
PostThreadMessage(dwThreadID, WM_QUIT, 0, 0);
}
Jason Henderson
quasi-homepage
articles
"Like it or not, I'm right!"
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Hope this is the right place to ask this question. Does anyone have a good example or link to some C source code on how I can use an ActiveX control? I have a Win32 program in C that I would like to add two controls to. I looked at the articles in this section and did a search on the web and MSDN but it's kind of hard to find something that is for C only. I have books on how to design COM objects and ActiveX controls but no examples on how to use them in C.
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