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Hi,
In C++ you can use inheritance, which is 'kind-of' relationship, or composition, which is 'has-a' relationship. You also can use the private inheritance, which is just a syntactic variant of composition.
Aggregation and containment are related to the COM. Aggregation is exposing a binary sub-object to the client as is using the QueryInterface. Not all classes are aggregatable and you may want to expose only part of the object's functionality, in this case you can use containment.
The best source of information on this topic is the Don Box's book "Essential COM".
Regards,
Alex Gorev,
Dundas Software.
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In simple terms aggregration means that the COM Component has an Internal Interface which is doing all your work though you are talking to front interface which redirects your job to its internal interface. As far as containment is correctly interpreted by me refers to the interface by which COM is exposing the rest of the interface contained inside it.
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I developing a webbrowser using CHtmlView.
But this browser is not repaint properly.
That is, i want to use CView::Invalidate() for browser repaint.
But this function is not work.
Anybody have sample code.
Thanks in advance.
dooly
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To have the view repaint, call CHtmlView::Refresh(). CHtmlView doesn't behave like a normal MFC view because all it does is wrap the WebBrowser control.
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Thank you for your reply.
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You can use CHTMLView::GetHTMLDocument to get the dispatch pointer for the document. Then you can get the window for the document. If you use Spy++, you will see that this has a classname of "Internet Explorer_Server". The following code will get you the handle to the window so that you can call InvalidateRect and UpdateWindow on it.
IOleWindow* pOleWindow = NULL;
HWND hWnd = NULL;
// pDispatch is the IDispatch pointer retrieved from GetHTMLDocument of CHTMLView.
HRESULT hr = pDispatch->QueryInterface(IID_IOleWindow,(LPVOID*)&pOleWindow);
if (SUCCEEDED(hr) && pOleWindow)
{
hr = pOleWindow->GetWindow(&hWnd);
// Ouput the classname to the debugger for verification
if (SUCCEEDED(hr))
{
TCHAR szClassName[256];
GetClassName(hWnd, szClassName, 256);
OutputDebugString(szClassName);
OutputDebugString(TEXT("\n"));
}
pOleWindow->Release();
pOleWindow = NULL;
}
I hope this helps,
-Erik Thompson
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Thank you for your reply.
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Hi,
I successfully crea the .chm file. But i want GUI like MSDN help.
Like two panes, on clicking an item in the left pane should give its contents on
right pane.
Thanks,
- Koteswara
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A GUI comes with Windows which is like MSDN! 
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Hi,
I can't figure out how to implement each interface in separate C++ class(not COM object) with ATL.
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why cant we have two methods with same name but different arguments in an interface ? I tried it in VB and VC it is giving problems
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Hi,
If you want to use your object with late binding, there is no way the GetIDsOfNames method of the IDispatch will know which ID to return, if it has two methods with the same names. So the problem is that the clients like VB or ASP do not know what to do with that kind of the objects.
As I heard this problem will be fixed in the new version of VB and C#.
Regards,
Alex Gorev,
Dundas Software.
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What you're talking about is called "overloading functions." Polymorphism is a different thing entirely!
Plus, you *can* have such methods if they are in an IUnknown-based (custom) interface, but you have to promise never to use it with VB...
Brian Hart
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COM. I realize that I have to use automation-compatible data types such as VARIANTs
and SAFEARRAYs. However, I'm having difficulty figuring-out exactly how to define the
method in IDL and interpret the data on the server side.
The data is a set of 29 variables, most of which are integers. Some are floats, with one
string and couple of arrays thrown in for good measure. Obviously it would be tedious
to set-up and use a method with 29 parameters. So, I'd like to pass all of the data in
one chunk if I can. Additionally, there will be 2 other chunks of data returned to the
client in the same method ... but that's a different question. The only thing I'm
trying to do now is get the chunk of data to the server.
In all that I've read, it seems that the best way to pass the chunks of data is using
arrays of VARIANTs. Is that true ? If so, how do I define the method interface in
IDL and how do I unpack the data on the server ?
Any guidance would be helpful.
Thank you,
Keith Gemeinhart
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Hi Keith,
You absolutely right... You have an option of passing 29 parameters to the method or you can use safearray. But safearrays are difficult to work with if you have different type of data like integers and strings...
The third option you have, which is the best if you have very complicated data that you need to pass/return to/from the method, is to use a COM object. You create a COM object with the different type of properties and pass/return it by interface pointer. The big advantage is that you can access the properties by names and even associate help strings with each property. The only issue is the performance... if you need to make many calls to such a method, it will take a lot of time to create and initialize the parameters object.
Regards,
Alex Gorev,
Dundas Software.
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Thanks for your reply. I have solved the problem ... and
in the near future, I will post a short description of how I
did it.
-Keith
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Hi
How do i show IE default context menu when user right click
on a WINDOW only ActiveX control...?
thanks
tomer
websplit
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Hi,
I created a atl com dll (full control) that consists of a simple object "a". I tried to fire events from the simple object "a" to the full control but I noticed that the full control did not receive the events. However, when I tried to created a new simple object with a sink interface within the ful control, it manage to receive the events fired from the simple object "a".
Why. What should I did in order for the full control to receive the events.
I call
HRESULT hr = AtlAdvise(mp_Mixer, this->GetUnknown(),DIID__IMixerCtrlEvents, &m_dwCookieMixerCtrl);
and hr return "0".
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Hi,
You have to implement the sink in the client to be able to advise for the events. Check the arctile from MSDN ID:Q181277 "SAMPLE: AtlSink Uses ATL to Create a Dispinterface Sink" for more details...
Regards,
Alex Gorev,
Dundas Software.
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Hi,
I am developing a COM component in VC++. I am deploying the component in MTS. I am using SQl Server 7.0 as my database.Also using ADO recordset and stored procedures.After deploying the component in MTS and run my client, I am getting the following error.Anybody can pls help me in this regard.
Error:
07-29-2000--19:46:56-Component CContactDB::GetAllContacts:-2146824584 :Unknown error 0x800A0E78! ADODB.Recordset! The operation requested by the application is not allowed if the object is closed.ÍýýýýÝ
GetAllContacts is my own function which will retrieve some info based on a query.
Kindly get back to me ASAP.
Thanks in advance.
Regds
guru
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Hi
Your problem is quite a common one in MTS. the problem may be because you are using a transactional component and the recordset is getting closed before you can access it. You must remember that MTS normally deactivates a component after every method call(thus the expression stateless objects)in which you Complete a transaction. What you must do is to ensure that your state is maintained for as long as you want. Thus the best way would be to use the DisableCommit of the IObjectContext interface at an appropriate place like for example in your IObjectControl::Activate method. This ensures that no transactions are completed until you specify a SetComplete on your IObjectContext method. I would advise making a method which does this SetComplete. Putting cleanup code in FinalRelease of your component is tricky because you cannot know how many times MTS will activate and deactivate your object. rather it is better to either make a cleanup function of your own or use the Deactivate method of IObjectControl.
I hope this helps to solve your problem. If not then email me and I can give you some sample code. I am even mailing you a copy of this suggestion.
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I'm writing a VB program that interfaces with another application. As long as a use GetObject("","ormec.mdesk.app") all works as expected and a new app is started. The problem is that I do not wish for a new app to be started. GetObject(,"ormec.mdesk.app") should work and return the current instance, but instead it returns error 429 even when the other program is running.
Most likely this is a problem somewhere in the server code, but I was hoping that maybe someone has had a similar problem and could give me some advice.
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How do I develop a solution to enable spell checking on a text box using Win 32 SDK.
Looking for a ideal solution.
Thanks
Siva
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How do I develop a solution to enable spell checking on a text box using Win 32 SDK.
Looking for a ideal solution.
Thanks
Siva
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Hello:
I'm developing a Server ATL component wich supports conneccion points. The client side is an MFC dialog based application. I sometimes need for the server advise to client. I've used the 'AfxConnectionAdvise' MFC global function to do it.
If I start the server (an executable server type) before the client the AfxConnectionAdvise function returns 'true' and there is no problem, but if the server is started by DCOM system (when I start the client) then the AfxConnectionAdvise function returns 'false'. ¿What can I do to solve this problem?
Thanks in advance,
Jose.
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