I have a COM Class in Vb.Net the code is like this
<comclass(class1.classid, class1.interfaceid,="" class1.eventsid)=""> _
Public Class Class1
#Region "COM GUIDs"
' These GUIDs provide the COM identity for this class
' and its COM interfaces. If you change them, existing
' clients will no longer be able to access the class.
Public Const ClassId As String = "74eb4206-6063-4ea1-b499-bfdd9f49f4bf"
Public Const InterfaceId As String = "ff2cdb8a-e1f9-464b-bb6f-ead5812d3630"
Public Const EventsId As String = "a8880b84-9a33-41f2-90f6-c6141835ee61"
' A creatable COM class must have a Public Sub New()
' with no parameters, otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.
Public Sub New()
Public Function MergeFiles(ByVal arrFiles() As String, ByVal strOutputFile As String) As String
When imported in VC++ (6.0) we are not able to get the function out. Any suggestions
Hmmm - you're using VB.NET but still using VC++ 6.0? That makes no sense what so ever...there's so much good support for importing COM objects easily in later versions of VC++...look up #import....
Open the type library for VB.NET DLL in the OLE/COM Object Viewer (open the Type Libraries branch of the tree view and select your project's type library - it'll be named after your project) to see what interfaces and classes the DLL exports. This'll show the DLL is properly registered and also show you what object you have access to.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
I'm using VC6 and the MapWindowGIS control, MapWindowGIS.OCX. It has many interfaces but few examples on how to use it using VC6. I'm kind of new to using COM so my terminology is probably incorrect to some degree.
The problem is I can get to one of the interfaces, IShapeFile, using their example using:
IShapefilePtr* pShapeFile = new IShapefilePtr;
HRESULT hr = pShapeFile->CreateInstance(__uuidof(Shapefile));
CreateInstance(), but when I try this on other interfaces such as IGrid and IGridHeader, CreateInstance() fails with the "Class Not Registered" error (0x80040154).
Since, the control, MapWindowGIS.OCX is registered, and I was able to get the IShapeFile interface, I'm assuming that I need to call QueryInterface() but the IGrid and IGridHeader interfaces are not part of the IShapeFile interface. So, I'm assuming then I need to get a pointer to the MapWindowGIS control but I'm not instantiating it directly since it is #import(ed).
VC6 created the .tli and tlh files and a CWnd derived class from the OCX called, CMap1. Is there something I can call in CMap1 that will return the main object's interface pointer so I can then call QueryInterface()?
I was able to get the IShapeFile interface, I'm assuming that I need to call QueryInterface() but the IGrid and IGridHeader interfaces are not part of the IShapeFile interface
No, but you normally would get, say, an IGridHeader interface by using the IShapeFile interfaces method QueryInterface asking it for an IGridHeader interface. All interfaces inherit from the base interface IUnknown which has three methods, QueryInterface being one of them. Having got one interface you can then use its QueryInterface method to get another interface implemented by the object.
Well, I'm kind of at a loss because I tried that with the IShapeFile interface (meaning I called QueryInterface for the IGrid interface on the IShapeFile interface) and I'm getting the E_NOINTERFACE error. That is why I was asking about how I get a interface pointer from the OCX control itself.
All of the examples are for VS 2008 in C# and VB.net. The only example they provide for VC6 is for creating a map using a shapefile hence, the IShapeFile interface.
I have the CLSID for the OCX is there some way I can get its main interface or IUnknown interface from the OCX using this CLSID ??
A search took me to the Mapwindow Wiki [^] where it says "An ESRI grid manager object provides functions which facilitate using ESRI grids with MapWinGIS". So it sounds to me as if you should be looking to work with the GridManager before trying to get an IGrid or IGridHeader.
This one can be a good alternative.
But its rather an out of the way we need to go. I think there would be some other straight froward methods might be available to have this information. like some flag or bit that will tell us about whether its COM PE or simple Win32 DLL /EXE
I am working on an OPC HDA Client where I am creating a Conenction with OSI PI HDA Server via below code. But at the time of Advise to the Server I am getting an error with error code = 0x80040202. The OSI HDA server is located on remote machine which has full DCOM configuration. I searched out and found that this happens due to CONNECT_E_ADVISELIMIT or CONNECT_E_CANNOTCONNECT. Below is the my code of Connect(). Can anybody help me what else I have to do to fix the problem.
#pragma region Code Added For AsyncOperations
ATL::CComPtr<::IConnectionPointContainer> subscripCpcObj = GetAtlInterface<::IConnectionPointContainer>((this->RawObject));
HRESULT hr = subscripCpcObj->FindConnectionPoint(__uuidof(IOPCHDA_DataCallback), &eventObjPtr);
// Get the servers side of the connection.IntPtr cbPtr = Marshal::GetComInterfaceForObject(this, OpcHdaEventSink::typeid);
callbackPtr = reinterpret_cast<IOPCEventSink*>(cbPtr.ToPointer());
// Advise for the events.
hr = eventObjPtr->Advise(callbackPtr, &cookie);
//Hold a reference to the connection point for shutdown.
this->callbackCookie = cookie;
this->callbackConnectionPoint = GetDotNetInterface<::IConnectionPoint>(eventObjPtr);
if(this->callbackConnectionPoint == nullptr)
OutputDebugString(L"HdaServer:->callbackConnectionPoint is NULL!");
I have created the COM component in VC6.0 using ATL 3.0
I am using it in VB6.0
I have added the BSTR Event.
I want to pass the string with NULL character in between the string from VC to VB
e.g. I want to fire a event with string "ABC\0XYZ"
So I can get the complete string in VB as ABCXYZ
 - indicates box as unicode character.
But I am getting only "ABC" string.
Please tell me the way to pass the string with NULL character from vc to vb.
Note: Without seeing any of your code, I'm just guessing...
It's probably because when you create the BSTR, you let it count characters to determine its length, rather than telling it what the length actually is. Any string length function in C/C++ will see a NULL as the end of string.
So, create your BSTR like this, telling it what its length is:
BST b = SysAllocStringLen(L"ABC\0XYZ", 7);
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
As I recall you won't be able to do as you want, either the ATL Event Wizard generated code sees the internal NULL and loses the rest (even with the BSTR length set) or VB will see a a NULL terminated string. I'm pretty sure You'll have do do more one way or the other. Maybe pass an array of characters?
The NULL character is your problem. Try replacing it with some other unique Unicode character which both parts of your application can recognise. Alternatively put the box character in your source string in the first place.
I am using namespace MSXML in my application to traverse and read XML file.But I have some confusion regarding MSXML is that this one is related to c++ DOM APIs na? And what its relation with COM?
And these both COM AND DOM are provoding different APIs?and then what is DCOM?
Please Suggest me something.I am too confused.
Thanks & Regards
Last Visit: 31-Dec-99 18:00 Last Update: 1-Oct-23 1:23