Suppose we have COM DLL registered in system registry. Now the requirement is to call that com dll functions in quartz.net.
I am thinking to make an auxiliary class that will contain implemented Execute method and using job data map I will call appropriate function in registered COM DLL. This is the way i am thinking to proceed.
Is there any other way that is easy and provide more flexibility.
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I am working with an application GUI program and a console program, which call a COM object, which calls a worker DLL. Let’s call them ConsoleApp, GUIApp, COM DLL, and Worker DLL. The two Apps use CreateObject (VBasic) or GetProcID(C#) to activate the COM object and call it. In turn, the COM object calls the Worker DLL.
Problem: My goal is to register the COM DLL once, and then to continually develop the worker DLL without having to reregister the COM object all the time. Things work as expected when using the ConsoleApp. I can call it and see a debug message from the Worker DLL. When I change the message and recompile the worker, the next invocation of ConsoleApp shows the expected Mbox message.
But things do not work as expected with the GUIApp. To pick up any new worker DLL code, I must reregister the COM object (of course the GUIApp is not alive during re-registration). But that defeats the purpose of me trying to split the big COM+Worker DLL into two pieces to avoid re-registering the COM object all the time.
I have read many web pages (including here) on COM objects, but have not found answers that might work for my goal of having the registered COM object call a Worker DLL that can change during development.
Q. Is this the normal case that all DLLs referenced and called by a COM object are somehow bound to the COM object at registration time? (Answered above and below.)
Q. Is there any way for me to register the COM object once and have it call a DLL that I can work on in development without constant reregistering the COM (calling) object every time I change the Worker DLL code?
That's my ultimate goal if it is possible (and it seems to work as expected for the ConsoleApp).
UPDATE: RomanR suggested that I use ProcessExplorer to see which process is hanging on to the Worker DLL once GUIApp has been shut down. I could find the Worker DLL when GUIApp was alive but could not find it when GUIApp was shutdown. At the moment, the visible evidence is questioning my statement that the GUIApp never lets go of the Worker DLL. I will have to figure out a way of absolutely showing whether rebooting GUIApp picks up the new versions of Worker DLL.
The problem occurred because I registered the COM object direct from VStudio as part of the build (as Administrator). In the COM VStudio project, the reference properties for Worker.DLL specified Copy Local = True. Therefore, at the time of registration, the COM object was referencing the locally-copied version of Worker.DLL and not the future (later modified) copies of Worker.DLL that were stored elsewhere.
If I set Copy Local = False, I could register the COM object, but it would fail because it could not find the Worker.DLL at runtime.
The easiest solution was to 1) close the GUIApp to release the COM and Worker DLLs, 2) modify the Worker DLL with new code, 3) and copy the new Worker DLL into the COM project\bin\Debug folder where the Copy Local=True operation would put it. That way the registered COM object would pick up the most recent Worker DLL from the expected location.
Another solution (that I have not tried) is to modify the COM code to dynamically load and instantiate Worker.DLL from some dynamic location. That looks like a good approach too, although it does not give compile-time feedback on Worker DLL methods, etc.
It is now well known how to make interface call to a DLL-implemented COM object in the registration-free environment. The question is the opposite:
How to make interface call from a DLL to a COM object implemented in EXE? Which manifests and which manifest sections should be used?
EDIT: May be it was not quite clear, but I meant in-process call. I want to call an object in the same process, but implemented in EXE rather than in DLL.
EDIT2: OK, I see things goes complicated, so I must explain the original problem. A C++ application implements IApplication interface and keeps pointer to it as a member. This member is returned by a public method accessible from anywhere by means of AfxGetApp().
There is also a mechanism allowing any customer to add his own C# "plugin" DLLs to our application. For such DLLs the IApplication interface is a key access point to the application's features. But these DLLs have no access to the main application's object.
To solve the problem, I added an auxiliary "ICreateApplication" object, which returns the original IApplication pointer. Any "plugin" DLL may create this auxiliary object and obtain from it the required interface. I implemented this object in some arbitrarily chosen DLL, and equipped it with necessary manifests.
This solution works well, but this "arbitrary choice" bothers me. I wonder, is there a possibility to implement "ICreateApplication" in the application object?
I have followed the example here: http://msdn.microsoft.com/en-us/library/vstudio/jj822931.aspx to create an In-proc Classic COM DLL using Windows Runtime Template Library (WRL). I am also able to modify to code to run the DLL as COM surrogate (wrapped inside DllHost.exe).
However, I couldn't find the way to create an out-of-process COM EXE using the WRL. There is a simple example using barebone COM API here: http://www.codeproject.com/Articles/3173/A-simple-yet-debuggable-COM-skeleton-code, but I'd like to know how I can utilize WRL to simplify that.
Thanks.
Yes it is possible. I just got one working. Here's the basics that are required, as compared to implementing an in-proc coclass.
Implement your coclass using WRL::RuntimeClass the same way you would for an in-proc class. (https://msdn.microsoft.com/en-us/library/jj822931.aspx)
In your main function, create a module object using WRL::Module<OutOfProc>::Create(), and call module.RegisterObjects() on startup, and module.UnregisterObjects() and module.Terminate() on shutdown.
You need to build a DLL to host the proxies: https://msdn.microsoft.com/en-us/library/windows/desktop/ms688707(v=vs.85).aspx
Static Registrations: DO register the Interface and the CLSID of your proxy stub. DO NOT statically register your coclass.
In the Client, when you call CoCreateInstance, be sure to use the appropriate CLSCTX. (I use CLSCTX_ALL when the hosting model is not important to the client.)
(I know it's been almost 4 years, but I had the same question this week.)
i was looking for some COM, .NET interoperability topics, and i came across a few legacy COM examples using c++, to round it up, i understood that u define every interface and coclass inside and idl (interface definition file) so other com aware languages can understand type information, but the only com class not defined in an idl file is the one derived from IClassFactory, can some one please tell why since other .NET languages need also to obtain a class factory to instintiate other com classes, so how can they understand the type information ??
Class factories are rarely used directly. In fact, if you needed to create a class factory first to create any COM object, how would you create the class factory itself?
COM library takes care of creating objects. E.g., if COM server is a DLL, it is required to export DllGetClassObject function. When a client wants to create a COM object, it calls CoCreateInstance specifying a CLSID. Using CLSID, COM library finds the server and (if it's a DLL) loads it and calls its DllGetClassObject.
This is just a couple of words on the topic. COM is a very big topic; you might have to start at the very beginning if you want to have complete understanding...
I'm using an interop COM assembly in my 1.1 VB.NET code, and when I try to set a property of a class, I get an InvalidCastException with the message "QueryInterface for Interface … failed."
Any ideas on this?
First, make sure your COM component is registered with regsvr32.exe.
Then, make sure any necessary marshalling support is also registered -- these come in one of two kinds:
1) proxy/stub DLL, usually called <YourComponent>ps.dll -- register this too with regsvr32.exe
2) Associated type library -- register this with regtlib.exe
If you used tlbimp on your DLL, try using regtlib to register the DLLs type library.