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I have to ask why you want a 'COM application'. Generally the only reasons for exposing existing code as COM objects are to support OLE linking and embedding, or to offer an automation interface to allow your program (and its data) to be manipulated by another application.
If you simply want to write some COM objects which run in another process context, with no user interface, you generally don't start from an existing program. If I were starting from scratch in C++ I would use the ATL AppWizard to generate a new EXE project.
The easiest way to support the first two requirements - OLE and/or Automation - will depend on the language and libraries you have used to produce your application. If you're already using MFC, you will probably want to use MFC's OLE support, which is based around the CDocument class. See the Servers: Implementing a Server[^] topic in MSDN Library.
If you're using C++ but not MFC you may find ATL helpful. However, it's pretty complex for a beginner.
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Actually its a requirement from the client. The existing app is used as a component manager. It is used to start/stop/activate/deactivate etc other modules. Now the client is changing the interfaces of the other modules. And we will have to use those changed interface. So its not a question of converting an exe to com, rather we have to make it a com server. How we do it is left to us. Either we can start from the scratch (that will be lot rework) and build a com application or use the existing one, make the necessary changes with respect to com standards and run it as a com server. I hope you got the point.
C++beginer
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Hi,
you need not write it from the scratch, if it is a c++ application, just register your application with SCM(service control manager)so that an entry is made into SCM for controlling your service..just what you need is two functions...
Service_main and
Service_CtrlHandler
in the start up you will be giving Service_main function to SCM and inside Service_Main you will be registering Service_CtrlHandler...normally Service_CtrlHandler will be containing evets like SERVICE_STOP, SERVICE_PAUSE e.t.c...so when ever you are performing an event like SERVICE_STOP, Service_CtrlHandler will be called to perform necessary functionality.Hope this will help you
mpk1979
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I think you've misunderstood the question - or possibly I have - but it sounds like this application needs to load COM objects, not be turned into a service.
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ohh, sorry i think i have misunderstood it
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So you're saying that the interface to the other modules is changing from a flat interface (calling into DLL entry points) to a COM interface (calling through an interface pointer)?
The client should be able to supply you with the interface that the other modules will expose. Ideally they would be able to supply the .idl file containing the interface definition(s) or the .h file that is generated from the .idl. Worst case, you might have to use #import to get the compiler to extract the interface(s) from a type library. It depends how the components are implemented; if they're in C++ you can probably get the .idl or header. You will have to compile the IDL with the MIDL tool.
If you just need to manipulate, call through, those interfaces, you don't really need to do anything special. I normally use ATL's CComPtr and CComQIPtr class templates to manage the reference counts properly. Include the atlbase.h header to use these templates.
If the component has to call back into your manager application, then you will have to check with the client how they intend to do this. The simplest way from your application's perspective is if you define a regular COM interface containing the methods that the component will call, and pass this to a method in the component's interface. You will then need to implement a class that implements the interface. You might find ATL helpful to do this.
If the components are written in some other language, they may not be able to handle this. They might be raising events using the Automation event mechanism. This will require you to implement the dispatch interface defined in the component's type library (shown as a 'source' interface) so that the component can call you back, and to call the component's connection point container to connect your callback interface to the component. See ATL's CONNECT sample[^] for an example of how to do this.
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Well our requirement is to turn our exe into a com server. The question is whether we can do so without starting from the scratch. What I am looking at is, we will add the COM interface and implementing classes to the project and build the exe as a com exe by, if possible changing the project settings. I was just wondering is there any well defined steps for this.
C++beginer
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yes, you need to add your functionality to interfaces and implement a class for it. i think ATL would be the best option
mpk1979
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I have created some applications using a lot of techniques to access the properties of the control in a form on screen, such as: Accessibility for Windows controls corperating with some supported API functions. However, for MathLab application, which is written by the Java language, it doesn't operate. Who knows, please tell me the way to solve this issue. Thanks.
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Hello, developers!
I have a problem, and i don't know how to solve it. Below i describe this situation:
I have a COM object(in C++) without TypeLIB and I there is a late bound client in C#.NET. During work
a COM object send different events to client. And i don't know, how i can recieve this events in C#. If a had a C++ client, i would write this code:
#include "stdafx.h"
#include <basetyps.h>
#include <unknwn.h>
#include <comdef.h>
#include <atlbase.h>
#include <atlcom.h>
#include <ocidl.h>
#include <iostream>
using namespace std;
_COM_SMARTPTR_TYPEDEF(IConnectionPointContainer, __uuidof(IConnectionPointContainer));
_COM_SMARTPTR_TYPEDEF(IConnectionPoint, __uuidof(IConnectionPoint));
_COM_SMARTPTR_TYPEDEF(IEnumConnectionPoints, __uuidof(IEnumConnectionPoints));
class CoFomatikEventSink : IDispatch
{
public:
enum DISPIDS
{
DISPID_OnStateChanged = 1,
DISPID_OnProgressChanged,
};
STDMETHODIMP_(ULONG) AddRef();
STDMETHODIMP_(ULONG) Release();
STDMETHODIMP QueryInterface(REFIID riid, void** ppv);
STDMETHODIMP GetTypeInfoCount(UINT *pctinfo);
STDMETHODIMP GetTypeInfo(UINT iTInfo, LCID lcid, ITypeInfo **ppTInfo);
STDMETHODIMP GetIDsOfNames(REFIID riid, LPOLESTR *rgszNames, UINT cNames, LCID lcid, DISPID *rgDispId);
STDMETHODIMP Invoke(DISPID dispIdMember, REFIID riid, LCID lcid, WORD wFlags, DISPPARAMS *pDispParams, VARIANT *pVarResult, EXCEPINFO *pExcepInfo, UINT *puArgErr);
CoFomatikEventSink() : cookie(0), refCount(1) {}
~CoFomatikEventSink() { Disconnect(); }
bool Connect(IUnknownPtr object);
bool Disconnect();
// Event Handlers
void OnStateChanged(IUnknownPtr state);
void OnProgressChanged(UINT value, const BSTR text);
private:
IConnectionPointPtr defaultConnectionPoint;
ULONG cookie;
ULONG refCount;
};
STDMETHODIMP_(ULONG) CoFomatikEventSink::AddRef(void)
{
return ++refCount;
}
STDMETHODIMP_(ULONG) CoFomatikEventSink::Release(void)
{
if(--refCount == 0)
{
delete this;
return 0;
}
return refCount;
}
STDMETHODIMP CoFomatikEventSink::QueryInterface(REFIID riid, void** ppv)
{
if(riid == IID_IUnknown)
*ppv = (IUnknown*)this;
else
if(riid == IID_IDispatch)
*ppv = (IDispatch*)this;
else
{
*ppv = NULL;
return E_NOINTERFACE;
}
((IUnknown*)(*ppv))->AddRef();
return S_OK;
}
STDMETHODIMP CoFomatikEventSink::GetTypeInfoCount(UINT *pctinfo)
{
*pctinfo = 0;
return S_OK;
}
STDMETHODIMP CoFomatikEventSink::GetTypeInfo(UINT iTInfo, LCID lcid, ITypeInfo **ppTInfo)
{
*ppTInfo = NULL;
return E_NOTIMPL;
}
STDMETHODIMP CoFomatikEventSink::GetIDsOfNames(REFIID riid, LPOLESTR *rgszNames, UINT cNames, LCID lcid, DISPID *rgDispId)
{
for(UINT i = 0; i < cNames; ++i)
{
if(_wcsicmp(rgszNames[i], OLESTR("OnStateChanged")) == 0)
{
rgDispId[i] = DISPID_OnStateChanged;
}
else
if(_wcsicmp(rgszNames[i], OLESTR("OnProgressChanged")) == 0)
{
rgDispId[i] = DISPID_OnProgressChanged;
}
else
return DISP_E_UNKNOWNNAME;
}
return S_OK;
}
STDMETHODIMP CoFomatikEventSink::Invoke(DISPID dispIdMember, REFIID riid, LCID lcid, WORD wFlags,
DISPPARAMS *pDispParams, VARIANT *pVarResult, EXCEPINFO *pExcepInfo, UINT *puArgErr)
{
switch(dispIdMember)
{
case DISPID_OnStateChanged:
{
if(pDispParams -> cArgs == 1)
{
OnStateChanged(pDispParams->rgvarg[0].punkVal);
return S_OK;
}
}
break;
case DISPID_OnProgressChanged:
{
if(pDispParams -> cArgs == 2)
{
OnProgressChanged(pDispParams->rgvarg[0].uintVal,pDispParams->rgvarg[1].bstrVal);
return S_OK;
}
}
break;
}
return DISP_E_UNKNOWNINTERFACE;
}
bool CoFomatikEventSink::Connect(IUnknownPtr object)
{
IConnectionPointContainerPtr connectionPointContainer = object;
IEnumConnectionPointsPtr enumConnectionPoints;
ULONG numConnectionPoints = 0;
connectionPointContainer->EnumConnectionPoints(&enumConnectionPoints);
if(enumConnectionPoints->Next(1, &defaultConnectionPoint, &numConnectionPoints ) == S_OK)
{
if(defaultConnectionPoint->Advise(this, &cookie) == S_OK)
{
cout<<cookie<<endl;
return="" true;
="" }
="" defaultconnectionpoint="NULL;
" cookie="0;"
="" false;
}
bool="" cofomatikeventsink::disconnect()
{
="" if(cookie)
="" {
="" defaultconnectionpoint-="">Unadvise(cookie);
defaultConnectionPoint = NULL;
cookie = 0;
}
return true;
}
void CoFomatikEventSink::OnStateChanged(IUnknownPtr state)
{
/* OnStateChanged handler HERE */
}
void CoFomatikEventSink::OnProgressChanged(UINT value, const BSTR text)
{
/* OnProgressChanged handler HERE */
}
// ===========================================================================
int main(int argc, _TCHAR* argv[])
{
::CoInitialize(NULL);
{
IUnknownPtr fomatik;
fomatik.CreateInstance("MyCOM.Application");
CoFomatikEventSink* ev = new CoFomatikEventSink();
ev->Connect(fomatik);
ev->Release();
}
::CoUninitialize();
}
But i don't know how i can implement IDispatch in C#? Yes, i know, that RCW and CCW do all work to marshal parameters and call functions, and implement IUnknown and IDispatch, but in my application it is neccesary to implement IDispatch myself, because i don't have a TypeLIB for COM object and that's way i can't cache DispIDs from another source.. I have been trying to write this event handler already 3 days, but unsuccessful!!!!
Plese, if anybody know how to solve this problem, help!
Big, hearty thanks in advance!!!!
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I advise you to use 'pre' tags, for readable code. For getting solution.
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Hello all
Could you please help me ?
I have a VC++ application which makes calls to a COM dll which is developed in c# and registered in GAC .
Randomly calls to functions in the dll makes the VC++ application crash with message "run time crash". But there is no __com_error exceptions happening on these calls .
Could any of you help me please to identify what could be the problem?
redindian
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Its not sufficient for answer
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hi all
i building a project use Com+
i have 3 Com+
the fist com+ after login i want only Admin can use it(permisstion in Database SQL)
the seacon com+ only Manage can use
the final everyone can use it
Can u hepl me
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With COM+ you can define roles which are containers for users and/or groups.
You can then authorise these roles to use different components.
Steve S
Developer for hire
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I am using VC++ 2005 Pro, created an MFC ActiveX control (From project types MFC, not ATL), then created an MFC dialog application to test the control. In the dialog application, right-clicked on the dialog box and selected 'Insert ActiveX Control', selected my control -- all that is ok. Right-click the control, select "Add Variable" and get the error "The Extender Provider failed to return an Extender for this object"
Any ideas what this means and how to fix it? 
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Dear all,
I need a DirectShow filter(eitheir source filter or transformer filter or renderer filter ) sample to get the knowledge about directshow filter development.
Manjunath S
GESL
Bangalore
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Hi,
How can I load XML Schema using VC++ 6.0. I'm trying to do this usning MSXML4.0, DOM APIs but I'm not able to read complex XSDs. Would anybody plz help me to do this.
How can I use ISchema, ISchemaElementPtr etc... SOM APIs?
Thanks
Srinivas
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See here[^] maybe its helpful for you
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I have successfully made a DCOM client and server, the client can call functions on the server. My trouble is trying to use MFC to create a connection point so that the server can call a function on the client.
On the client side I created a class ISimpCliAuto derived from COleDispatchDriver that has the exposed functions of the server. This class has a clsid, IID_ISimpCliAuto.
On the server side I have the following macros in the header file of the exposed class, CSimpServDlgAutoProxy:
BEGIN_CONNECTION_PART(CSimpServDlgAutoProxy, Alert)
CONNECTION_IID(IID_ISimpCliAuto)
END_CONNECTION_PART(Alert)
DECLARE_CONNECTION_MAP()
In the SimpServDlgAutoProxy.cpp I have the macros
BEGIN_CONNECTION_MAP(CSimpServDlgAutoProxy, CCmdTarget)
CONNECTION_PART(CSimpServDlgAutoProxy, IID_ISimpCliAuto, Alert)
END_CONNECTION_MAP()
On the client side I call CoCreateInstanceEx() and get an LPUNKNOWN m_pUnkServ. I call m_pUnkServ->QueryInterface() to get an LPDISPATCH which I can use in AttachDispatch(LPDISPATCH) and call exposed functions on the server side. I do not call m_pUnkServ->Release() at this point.
The problem occurs when I attempt to use m_pUnkServ in AfxConnectionAdvise(m_pUnkServ,...). The failure occurs within at the call
LPCONNECTIONPOINTCONTAINER pCPC;
HRESULT hr = m_pUnkServ->QueryInterface(IID_IConnectionPointContainer,(LPVOID*)&pCPC);
The hr indicates "No such interface supported." This is the result locally as well as over a network. The interface in question I think is the connection point container. But isn't all that supported by the macros above in the server? What am I doing wrong?
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Hi,
I am passing a BSTR as an argument in a connectionpoint method. Everything is working fine except that when the BSTR is received by the client, it just gets the first character of the string.
Does anyone know how to solve this?
Thanks...
---
![Beer | [beer]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/beer.gif) Hakuna-Matada
It means no worries for the rest of your days...
It's our problem free, Philosophy
![Jig | [Dance]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/jig.gif)
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Is this a UNICODE or ANSI BSTR ?
Darka [ Xanya]
"I am not a slave to a god that doesn't exist."
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By definition, a true BSTR can only be UNICODE. 
Steve S
Developer for hire
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