Re: Handling events with COM object as param - COM Discussion Boards

10-Dec-03 8:51

Hi,
I am well done by responding COM events with simple data types( say VTS_I4). However, on topic that is not covered anywhere (and I spent days looking) is when the event has a COM object as a parameter. Say for instance in your sample that the addition is not on 2 integers but on 2 matrixes. The OnAdditionDone event would therefore pass a IMatrix * obj (VT_DISPATCH) pointer instead of an integer (VT_I4).

How would you implement the event handler on the client side, and how would you actually start using the IMatrix pointer to access its members (tried everything I could think of, wither it doesn't compile or compiles but crashes, always get the 'first chance exception (OLEAUT32.DLL): 0xC0000005: Access Violation.). In other words, how to complete this:

void CCoCaller::OnAdditionDone(IMatrix *result)
{
// How to implement this so that it works:
BSTR str; result->get_Name(str);
}

MSDN gives 2 samples on how to implement IDispEventSimpleImpl and IDispEventImpl using Word and Excel veents, none of them show events that pass COM objects as parameters.

Any help would be very useful. Thanks a lot
Sleepy | :zzz:

Abhishek Srivastava10-Dec-03 21:40

Abhishek Srivastava

10-Dec-03 21:40

Hi there ,
once i have tried the same also..and it worked fine.

Suppose i have to pass IInterface instance to the client thru a Event method ThrowInter(IInterface *iFace)

this is the code where i fired this event and passed the IInterface pointer.

IInterface *iFace;
CoCreateInstance(CLSID_Interface, NULL, CLSCTX_ALL, IID_IInterface, (void **) &iFace);
Fire_ThrowInter(iFace);

Now this is my client code where i caught the fired event and IInterface instance

void CContainerDlgDlg::OnThrowInterTinterface1(LPDISPATCH interfac)
{
IInterface *iFace=reinterpret_cast<iinterface *="">(interfac);
iFace->ShowMessage();
}

but in client i have to include the header file of IInterface.

and then simply reinterpret casting , i was able to access my IInterface methods and properties
Smile | :)

let me know if u r also doing the same Smile | :)

Abhishek Srivastava
Software Engg (VC++)
India ,Noida
Mobile no 9891492921 Smile | :)

Steve S11-Dec-03 5:37

Steve S

11-Dec-03 5:37

You really shouldn't do that, it's the kind of thing that gives COM a bad name. Better would be to get an IDispatch from the object and fire that, then use QueryInterface at the client end, or use IUnknown and do the same.

If you remote (out of proc or off-machine) interfaces, then there is postively absolutely NO guarantee that your cast is safe, since a proxy/stub may well have only the same number of methods available in an IDispatch interface, and the rest of your interface's function table may/will be inadmissible.

Steve S

NotProfessional11-Dec-03 9:42

11-Dec-03 9:42

The key is I do not have the source code for the COM nor the header though. So I cannot include the header. Thanks for your suggestions anyway. WTF | :WTF:

NotProfessional11-Dec-03 10:27

11-Dec-03 10:27

Thanks so much, Abhishek!
I got it done, the trick is I need to declare the LPDISPATCH and convert to my desired COM refrence type explicitly. However, I declare the handler function the same as what is described in .tlh!
I want to correct is that you don t have to get the COM header, what you need is simply import the dll and use the smart pointer.

IIS - Automation - COM - ASP

Vi211-Dec-03 2:54

Vi2

11-Dec-03 2:54

I think that you should write

BSTR str;<br />
result->get_Name( & str );

Or better

CComBSTR str;<br />
result->get_Name( & str );

With best wishes,
Vita

tourdata9-Dec-03 23:46

tourdata

9-Dec-03 23:46

Hello
We have a big problem with our System.
We developed a Web-Side with IIS and ASP and a Automation-Dll(COM) written in MFC 7.0. A User can login and the ASP creates the COM-Object in the ASP-Session-object. All Information are stored in the Com-Object. It's installed as in-Process and the COM-Object is set to Neutral-Threadingmodel.
Now, when the COM-Object crash, sometimes the IIS restarts and all User have to login again. Sometimes the IIS can't restart and we have to restart the W2k Server.
I changed the settings in the IIS to Out-Process (so it isn't in the same memory) but nevertheless the IIS restart on any COM-Object-Crash.

What is the best way to develope a big existing MFC-Application to a COM-Object and using it as a WEB-Application with ASP. There are about 100 USer in the same time online....

Volker

Re: IIS - Automation - COM - ASP

Xiangyang Liu 刘向阳12-Dec-03 4:29

Xiangyang Liu 刘向阳

12-Dec-03 4:29

To prevent IIS crash, you could try to register your com object in COM+ as a "Server" application. Here is what you need to do:

1. Register your com object.
2. Create a blank COM+ app, make sure it is a "Server" not a "Library" app.
3. Import your com object (add it as a component to the COM+ app).

Then you can use it in your ASP pages (by calling CreateObject). The com object will not be running within the IIS process. You have to test whether this solves your problem or creates a new problem, etc.

The best approach is to fix the bug so that it won't crash, of course.

Good luck.

My articles and software tools

How to call 16 bit component in a 32 bit Operationg system

Mohan Babu D9-Dec-03 20:32

Mohan Babu D

9-Dec-03 20:32

Hi,

I have a doubt. Can we make use of a component developed in 16 bit Operating system in 32 bit O.S. If yes, then how does a 16 bit component will be resolved in 32 bit O.S ? Is there any work around to call 16 bit component in 32 bit component ?
Please give me a brief solution with example,if possible.

Thank you

Re: How to call 16 bit component in a 32 bit Operationg system

Abhishek Srivastava9-Dec-03 22:05

Abhishek Srivastava

9-Dec-03 22:05

Hi dear

u can call a component devloped in 16 bit OS in 32 bit OS using Thunking mechanism.
there are 32-bit Generic Thunk Functions using which u can call ur component.
One can also access the component devloped in 32 bit os in 16 bit OS ,using the same thunking mechanism for which u have to use 16-bit Generic Thunk Functions.

u can refer to "THUNKING" topic of MSDN.

Abhishek Srivastava
Software Engg (VC++)
India ,Noida
Mobile no 9891492921 Smile | :)

COM and ATL

Judah Gabriel Himango9-Dec-03 5:49

Judah Gabriel Himango

9-Dec-03 5:49

I have a COM object I'm using in an ATL project. One of the COM object's exposed interfaces is called IWTonload. According to the COM object's documentation, a class implements the IWTonload by having a method in the class called .onloadComplete.

In Java, I would go

<br />
public myClass implements IWTOnLoad<br />
{<br />
...<br />
void onLoadComplete()<br />
{<br />
}<br />
<br />
}

In C# I would go

<br />
public myClass: IWTOnLoad<br />
{<br />
void onLoadComplete()<br />
{<br />
}<br />
}

How would I implement this IWTOnLoad COM interface in a C++ ATL project? Any help is greatly appreciated.

The graveyards are filled with indispensible men.

Re: COM and ATL

Abhishek Srivastava9-Dec-03 21:52

Abhishek Srivastava

9-Dec-03 21:52

Hi there ,

In ATL it can be done very easily , insert an ATL class in ur project .
Now insert ur component in the same project .
In Class view , right click on ur ATL class , a menu will pop up , click on inplement interface.
now browse for ur interface select it and click on implement.

Abhishek Srivastava
Software Engg (VC++)
India ,Noida
Mobile no 9891492921 Smile | :)

Looking for a 'RPC/COM Call Monitor' tool

ohadp9-Dec-03 2:00

ohadp

9-Dec-03 2:00

I've heared about such a tool by Microsoft, but I can't find it.

I need to monitor all the COM/RPC calls a process makes...

thanks

Does this COM dll look unregistered?

gregcost5-Dec-03 1:50

5-Dec-03 1:50

Because it doesn't to me.

Exception:----------------------------------------------------------------------------------
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in Test Form exe Additional information: COM object with CLSID {3050F48A-98B5-11CF-BB82-00AA00BDCE0B} is either not valid or not registered.

From Registry:------------------------------------------------------------------------------
[HKEY_CLASSES_ROOT\CLSID\{3050F48A-98B5-11CF-BB82-00AA00BDCE0B}\InprocServer32]
"Class"="mshtml.CEventObjClass"
"Assembly"="Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
"RuntimeVersion"="v1.0.3705"

[HKEY_CLASSES_ROOT\CLSID\{3050F48A-98B5-11CF-BB82-00AA00BDCE0B}\InprocServer32\7.0.3300.0]
"Class"="mshtml.CEventObjClass"
"Assembly"="Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
"RuntimeVersion"="v1.0.3705"

From Gacutil /L: (GAC)----------------------------------------------------------------------
Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, Custom=null

And Finally my own investigation of 3050f48a-98b5-11cf-bb82-00aa00bdce0b using---------------------------
Dim csCEventObjCLASS As New Guid("3050F48A-98B5-11CF-BB82-00AA00BDCE0B")
Dim C_CEventObjCLASS As Type = Type.GetTypeFromCLSID(csCEventObjCLASS, True)

CLASSName mshtml.CEventObjClass
IsClass) TRUE
IsCOMObject) TRUE
IsInterface) FALSE
IsPointer) FALSE
Namespace) mshtml
Module) MSHTML.dll
Name) CEventObjClass
GUID) 3050f48a-98b5-11cf-bb82-00aa00bdce0b
Assembly) Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Assembly.Location) c:\winnt.0\assembly\gac\microsoft.mshtml\7.0.3300.0__b03f5f7f11d50a3a\microsoft.mshtml.dll
Assembly.CodeBase) file:///c:/winnt.0/assembly/gac/microsoft.mshtml/7.0.3300.0__b03f5f7f11d50a3a/microsoft.mshtml.dll
Assembly.GlobalAssemblyCache) TRUE
Assembly.FullName) Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Assembly.GetCallingAssembly) System.Windows.Forms, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
Assembly.GetEntryAssembly) Test Form Focus, Version=1.0.1434.13227, Culture=neutral, PublicKeyToken=null
Assembly.GetExecutingAssembly) Test Form Focus, Version=1.0.1434.13227, Culture=neutral, PublicKeyToken=null
Assembly.GetExportedTypes) System.Type[]
Assembly.GetFiles) System.IO.FileStream[]
Assembly.GetLoadedModules) System.Reflection.Module[]
Assembly.GetManifestResourceNames) System.String[]
Assembly.GetReferencedAssemblies) System.Reflection.AssemblyName[]
Assembly.GetModules) System.Reflection.Module[]
AssemblyQualifiedName) mshtml.CEventObjClass, Microsoft.mshtml, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
FullName) mshtml.CEventObjClass

Thanks, GregC

Stephane Rodriguez.5-Dec-03 2:47

5-Dec-03 2:47

I don't think it's a matter of registration. After all Microsoft.mshtml is the interop assembly for InternetExplorer's mshtml.dll, and this wasn't registered Internet Explorer wouldn't work.

This exception can be thrown more about an interop issue (bad use of objects or interfaces, or even if the object inside is not yet initialized.

When I had this kind of issues last year, I tried adding code to my code sequence (even with stupid method calls) only to make sure the underlying objects were initialized and valid.

Good luck!

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gregcost5-Dec-03 5:47

5-Dec-03 5:47

Hi Stephane,

Yes it is Interop but isn’t the underlying code in MSTHML.dll? Or am I missing something? The statement is also so simple.

Dim objevent As New CEventObj()

Of interest when I create a Console.WriteLine(objevent.returnValue),
property in the CeventObjClass, Studio based on the dim does not complain and shows me the correct object list to select .returnValue from the class.

Thanks, GregC

gregcost5-Dec-03 5:55

5-Dec-03 5:55

Hi Stephane,

One more thing even if I spell it all out like

Dim objevent As New mshtml.CEventObjClass()

I get the same result

Thanks, GregC Frown | :(

Stephane Rodriguez.5-Dec-03 6:15

5-Dec-03 6:15

gregcost wrote:
Yes it is Interop but isn’t the underlying code in MSTHML.dll?

Exactly.

Interop issues can be one of these, in order of importance :

underlying (unmanaged) object not initialized
bad parameter or interface marshalling
security, access denied

In your case, if could be an interop issue, but it could just be that the object you are using is lacking a context.

I have just taken a look at mshtml.dll, and CEventObj is an interface, not an object. So you will never successfully create an instance of CEventObj (it's a pity that they have given it such a name).
The implementation for the interface is CEventObjClass.

Creating an instance of CEventObjClass should work better.

That being said, I think it's best to stick with an existing sample. By default, I wouldn't pledge that you can create a useful and relevant instance of CEventObjClass by yourself. Most of the time with mshtml.dll, what you do is "get" objects down from the current document object.

Your code might be ok, I don't know though.

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gregcost5-Dec-03 8:59

5-Dec-03 8:59

Hi Stephane,

Sorry, yes the dim I wrote as I was writing the message is the interface, I left off the Class suffix. I have tried it a bunch of different ways

Dim objevent As New CEventObjClass()
Dim objevent As New mshtml.CeventObjClass

In fact none of the classes will work in the dll. I get the same COMException for any I try.

What I’m actually trying is to get MS Knowledge Base Article 279535 to work. The short program uses a property in the class CEeventObjClass to disable script error checking for forms hosting a WebBrowser control. For whatever reasons Microsoft did not implement this disabling script feature for WebBrowser controls by selecting it from IE (even through it is really the same object). It is available for IE. So they supply you with a code example in VB6 not VB.net to address this problem. Actually I can understand why they did it this way because you might want to disable script error checking for IE but not completely across any applications that host Web controls on the same system. So since I’m trying to rework MS code I’m not flying to blind… Or am I!!!!

Well, if you think of anything please let me know and thanks for your help!

Thanks, GregC

Stephane Rodriguez.5-Dec-03 9:33

5-Dec-03 9:33

Don't get it wrong, but I think you don't understand what you are doing.

The support KB article you refer to NEVER creates an instance of the CEventObjClass.

Quite the contrary, the only thing it does is change a property value on the event interface being passed by the IE event dispatch mechanism.

In the support KB article, objEvent is that interface. It's created by IE and passed along to subscribers.

Now that I know what's going on, I wonder what's your problem here. You just need to reproduce the code that is given in the support KB article. There is no "New event something " involved in here.

Good luck! Wink | ;)

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gregcost5-Dec-03 17:23

5-Dec-03 17:23

I’m a Network engineer I’m not programmer heavy and I think I understand what you are saying.

I did try the code exactly as stated in the article but I ran into other problems (below) with the dim statements. What I was attempting to do was to go a different way. I was hoping I could set the field True in the CEventObjclass (which I thought this code is trying to do) and if I could do that I was hoping I could set return value true always regardless of an onError event so that I could continually disable script error checking.

Ok that being said are you saying that the field being made available through the interfaces (really address pointers), passed in a sense to its subscribers (a webbrowser control) is really a property of IE? Am I correct in understanding what you are saying?

I’m getting Com errors with the standard dims described in the article.

The first Interface dim works fine:
dim withevents for HTMLDocument

The second interface dim does not work:
Dim WithEvents objwind As New mshtml.HTMLWindow2()
Additional information: COM object with CLSID {D48A6EC6-6A4A-11CF-94A7-444553540000} is either not valid or not registered.

And of course the third does not work either:
Dim objevent As New CEventObj() did not work as stated in the article
Additional information: COM object with CLSID {3050F48A-98B5-11CF-BB82-00AA00BDCE0B} is either not valid or not registered.

In trying to resolve the COMException for the dim of Interface CEventObj I have tried un-registering and re-registering the interop dll Microsoft.mshtml.dll in \Program Files\Microsoft.net\Primary Interop Assembles\

Any ideas?

I get the same kind of error when trying the code it exactly in the KBase Article. Please let me know if my understanding now about passing the field is correct.

After all I never get upset about this stuff everything we do is a learning experience.

Thanks, GregC

Stephane Rodriguez.5-Dec-03 20:01

COM event cannot emit through Wrapper Class

5-Dec-03 20:01

gregcost wrote:
CEventObjclass (which I thought this code is trying to do)

Change your glasses.

gregcost wrote:
I could set return value true always regardless of an onError event so that I could continually disable script error checking.

Yes, there is another way to disable script error when you are hosting the web control. The way it is explained in the support KB article is a transient way of disable script errors. In fact, they are not disabled. You subscribe the onerror event, and wheenever an error occurs you block it rather than let IE popup a message box.

This is transient. This code must be executed for each new web page being loaded.

There is a way to do it for the entire life cycle of your application, and without changing the users options in the registry (Internet options / Advanced / ...). I guess you can find a support KB article but from what I remember, you have to use the ExecCmd method and pass it a special OLECMDID_DISABLEERRORXXXXXXX cmd id (I don't remember the name). You won't find the cmd id in the MSDN doc though, for some reason.

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NotProfessional4-Dec-03 9:27