COM

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How to use one instance of a COM object in different processes? Jawid5-Jul-02 5:37 Jawid 5-Jul-02 5:37  Hi everyone, I am not able to find a way how to use the only one (common) instance of my COM object from several processes. Here I see the only solution of multiple instances and that way I lose some of the pointers. Can anybody guide me how to do that? Thanks, Jawid Re: How to use one instance of a COM object in different processes? Scot T Brennecke6-Jul-02 4:53 Scot T Brennecke 6-Jul-02 4:53  Have you tried using RegisterActiveObject, to put your object in the ROT? Then you can use GetActiveObject. Scot Brennecke Software Developer VC++ MVP Re: How to use one instance of a COM object in different processes? 8-Jul-02 4:22 8-Jul-02 4:22  I found that macro : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/vcoriATLMacrosAlphabeticalReference.asp The particular one is : DECLARE_CLASSFACTORY_SINGLETON Hope this helps. Re: How to use one instance of a COM object in different processes? 8-Jul-02 4:17 8-Jul-02 4:17  If you com object was developed using ATL then there is a macro you can use to make it a singleton, meaning only one instance of it will be created and shared between all clients. Im sorry but i can't remeber what the macro is, its something like ATL_DECLARE_SINGLETON. Have a poke around in the MSDN although i found it in one of the wrox atl books. Re: How to use one instance of a COM object in different processes? Pedro Miranda8-Jul-02 4:47 Pedro Miranda 8-Jul-02 4:47  Hi, I’m sorry but I did not fully understand your question? You want to use the some instance of a COM object in different processes or different threads in the same process? If you want to pass a pointer to a object to another thread in a running process you have to be aware of the COM Threading Model (Apartments) and Marshalling see http://www.codeguru.com/activex/COMApartments1.html and http://www.codeguru.com/activex/COMApartments2.html . . If you really want different processes to access the same COM object, then this last has to be implemented in a out-process (.exe) COM server having the class factory returning the same object every time a instance of that class is requested. Remember that using an out-process com server you’ll be linking whit a proxy/stub dll (Marshalling). http://www.codeguru.com/activex/MiniDcom.html I recommend you reading Essential COM (Don Box), ATL Internals (Brent Rector) and Learning DCOM (Thuan L. Thai) Re: How to use one instance of a COM object in different processes? Jawid9-Jul-02 16:18 Jawid 9-Jul-02 16:18  Hi Guys, Thanks for great help. All of those advices seem very helpfull. I tried the solution with macro for singleton object and it works nice. Thanks, Re: How to use one instance of a COM object in different processes? Ed K12-Jul-02 8:09 Ed K 12-Jul-02 8:09  Make sure that it is an exe service rather than a dll service. A dll singleton loads a different instance per app. An exe will have only one instance. ed The nice thing about egotists is that they don't talk about other people. Lucille Harper Can somebody please answer this? JohnnyG3-Jul-02 14:26 JohnnyG 3-Jul-02 14:26  Ok. I'm trying to use a COM OCX object in a C program. I've done some research and found out how to call and instantiate a COM object from C. However, I do not know how to generate a header file for object type or interface declarations. SOPTEST replied with some useful info but all I can find out is info on how to develop a COM object using C and not how to use an existing one that is already in the registry that I didn't develop. I want to use MSCOMM32.OCX in a C program. How do I get the declaration for the IMSComm and other interfaces? I know how to get the IUknown interface, call QueryInterface, etc. And, I know that getting an interface pointer is really a void** so I could create a void pointer and call it anything I like and use it but that doesn't seem right or is it???? I've learned how to view the typelib, CLASSID, etc. from OLE/COM Object viewer so I don't think I'm an idiot, I just need some help. Is there someway of interpreting the type library and converting it into a header file that I am not aware of? Anybody?? Re: Can somebody please answer this? soptest3-Jul-02 14:39 soptest 3-Jul-02 14:39  Use "oleview" to open type library. From "File" menu you can "Save as" *.IDL, *.H or *.C file. If you save it as *.IDL file then compile it with MIDL compiler to generate proxy/stub files. soptest Re: Can somebody please answer this? JohnnyG3-Jul-02 14:59 JohnnyG 3-Jul-02 14:59  I used "oleview". I did not know you could save .c or .h files from there but when I tried, it didn't work. Apparently, it uses a console window but the error happens so fast and the console window closes before I can see it. However, I was able to save the .idl file. But, going from using VC++ before with Add To Project | Components and Controls that generates all C++ wrapper classes and as you say proxy/stub files for out of process. Re: Can somebody please answer this? JohnnyG3-Jul-02 15:36 JohnnyG 3-Jul-02 15:36  I think I got it now. I was finally able to save a .c and .h files to the default directory (system32). I still got warnings or errors but I couldn't tell what they were. Looking at the contents it has the proper extern "C" declarations Cool! Thanks again, SOPTEST Re: Can somebody please answer this? Stuart Dootson3-Jul-02 14:45 Stuart Dootson 3-Jul-02 14:45  If you're using MSVC++ (and what else would you be using !!), you can use '#import' to import COM objects. This will generate the required header files automatically when you compile the code. The one pain is that (with VC6, but not VC.NET, IIRC) you need to enter an absolute path to the DLL or OCX or whatever. (I've just looked it up - VC++NET lets you use a progid to say what class you want). MSDN (the one you get with VC++) should hopefully have enough info to get you started. Just one thing - by default, VC++ will generate wrappers for the COM class - this may not be what you want. Stuart Dootson 'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p' Re: Can somebody please answer this? Stuart Dootson3-Jul-02 14:47 Stuart Dootson 3-Jul-02 14:47  Whoops - just read your message properly - you say you're using C, as opposed to C++, so this may have been of no use whatsoever Stuart Dootson 'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p' Unregistered objects Stuart Dootson3-Jul-02 14:21 Stuart Dootson 3-Jul-02 14:21  OK - not really a problem, but is there anything supremely wrong with this: I've got some COM objects I'm using as helpers to get a scripting application (using IActiveScript with a user-selectable script engine) working (specifically, I've got an IActiveScriptSite implementation and some IDispatch-based objects that I'm inserting into the scripting namespace with IActiveScript::AddNamedItem). BUT...these objects are not registered COM classes, because they're just classes in a standard Win32 executable, not a COM server executable - I create them using 'new CComObject<class name>' and manage them with _com_ptr_t..or is it CComPtr - can't remember which right now. It all seems to work - but is there any reason that I should be using properly registered servers & objects & things? Stuart Dootson 'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p' Re: Unregistered objects Scot T Brennecke6-Jul-02 4:50 Scot T Brennecke 6-Jul-02 4:50  Nope. If you're not going to use the objects outside the scope of your application, there's no reason to register them. Scot Brennecke Software Developer VC++ MVP First Time COM user w/ MSXML electronicman_x3-Jul-02 9:35 electronicman_x 3-Jul-02 9:35  I'm trying to utilize Microsoft's MS XML 4.0 parser to obtain some data from an XML file. I'm using C++ so im I'm having a bit of trouble writing a simple console app that can find an XML node of my choice and retrieve data associated with it. I am trying to utilize the XML DOM Method GetAttribute. (as seen on MSDN @ http://msdn.microsoft.com/library/en-us/xmlsdk/htm/xml_mth_dg_5rfo.asp I've worked through another example tutorial which creates a very simple app that loads the whole XML document and prints it to screen. I have no trouble with that but when I tried to utilize the MSDN example for GetAttribute, the code is riddled with problems and I have been unable to over come them. I'm sure if i saw a simple app that did what i was looking for i would understand how to use this better, but i have looked all over for such an animal and they are either way too big or way to simple to get anything from them. I am also having some troubles fully understanding _variant_t and _bstr_t. If anyone can provide some advice or a very simple example (like something that can read 10 line xml file and find one tag in it and print its data), I would be grateful. PS: My problem may stem from: GetAttribute code: MSDN says it takes two parameters but it will not compile that way. SetAttribute appears to take similar parameters and it will compile with 2 parameters. Thanks Jeff Rothenberg Project Engineer Vector CANtech, Inc. Addin load problem Zizilamoroso3-Jul-02 4:38 Zizilamoroso 3-Jul-02 4:38  I've followed the tutorial about creating office addin's. The one I've created is an excel addin. It doesn't do anything, it's just a minimal addin. But it doesn't show up in the excel addin-list, even though it's registered in windows registry. The loadbehaviour should be set to 3 for automatic loading. After compiling the project, using regedit shows 3 for loadbehaviour. So far so good. But after running excel, eyeballing the addin is not there, the loadbehaviour in regedit changed to 2 ?????? What's going on here? [VISUAL STUDIO 6.0] [MFC] [WIN98/2] Bluute tette! Re: Addin load problem Amit Dey4-Jul-02 10:31 Amit Dey 4-Jul-02 10:31  Hi, as far as Excel addin is concerned, there are a few caveats as I have found out. If you have followed my tutorial and have a bare bones COM dll ready, to properly register it here's some info: 1) the registration key is to be created as usual at HKCU(or HKLM)->Software->Microsoft->Office->Excel->Addins->[Your Addins ProgID]. Now under this, apart from the usual FriendlyName,LoadBehavior and Description, you have to add 2 more entries. These are : FileLocation - a string value of the physical path where the dll is located. CommandLineSafe - a DWORD value(0 - unsafe 1-safe) thus for my ATL Excel2000 addin project, the additions to the registry script(.rgs) are: HKCU { Software { Microsoft { Office { Excel { Addins { 'XLAddin.Addin' { val FriendlyName = s 'Excel2000 Addin' val Description = s 'ATL COM Excel Addin' val LoadBehavior = d '00000003' val CommandLineSafe = d '00000001' val FileLocation = s '%MODULE%' } } } } } } } with this, my addin gets loaded at startup.now as to the weird registry value changes, if the CommandLineSafe is 0,(i.e. addin is not safe to load) or the entry is missing ,Excel increments or decrements the LoadBehavior value, as some kind of a precaution. happy addin programming. 'My capacity for happiness', he added, 'you could fit into a matchbox without taking out the matches first'. - Marvin, the robot. Amit Dey sonork: 100:18407 msn: visualcdev Re: Addin load problem Zizilamoroso5-Jul-02 6:45 Zizilamoroso 5-Jul-02 6:45  ok tnx will try it... [VISUAL STUDIO 6.0] [MFC] [WIN98/2] Bluute tette! Get the caller thread Id of a marshalled interface 2-Jul-02 7:46 2-Jul-02 7:46  do you know in a method call how to get the caller thread id if the interface has been marshalled ? the problem is if the interface has been marshalled the GetCurrentThreadID return obvously the ID of the marshalled thread on which the interface has been marshalled. But how to get the thread id of the calling thread ? thanks in advance Re: Get the caller thread Id of a marshalled interface Len Holgate4-Jul-02 12:42 Len Holgate 4-Jul-02 12:42  why do you need to know it? Len Holgate www.jetbyte.com The right code, right now. Re: Get the caller thread Id of a marshalled interface 4-Jul-02 21:50 4-Jul-02 21:50  Len, it's funny you answer with a question anyway it's a bit complicated to explain in few words. I've used the IMessageFilter and it's not perfect but it works (only in STA) ciao Re: Get the caller thread Id of a marshalled interface Len Holgate4-Jul-02 22:22 Len Holgate 4-Jul-02 22:22  Anonymous_com wrote: it's funny you answer with a question It's the only way to be sure that the person asking the question is asking the right question. There's no point in diving in to answer a question if you don't understand why the question is being asked and the context in which your answer will be used. This is especially true when the question is 'strange' ie something that you don't think the questioner should need to know. Often such a question arises from the fact that someone's already made a whole load of decisions to get to the point where they need to ask the 'strange' question. So by finding out why they need to ask the question you can often point out a more conventional way to solve the actual problem that they have and in doing so remove the need to answer the original question. However, you don't give me any context, so I'll guess You may be attempting to deal with reentrancy issues during COM method calls. I'd solve the problem differently Len Holgate www.jetbyte.com The right code, right now. Re: Get the caller thread Id of a marshalled interface 4-Jul-02 22:43 4-Jul-02 22:43  Len, nothing to do with reentrancy issues during COM method calls. I've got an interface marshalled between different threads and the interface under certain circumstancies need to know which thread has been calling to provide different services because this thread is not so safe to produce good result using this method. The problem of marshalling an interface is that during the method call the GetCurrentThreadId obviously return the marhsalled thread id ciao Re: Get the caller thread Id of a marshalled interface Len Holgate4-Jul-02 22:49 Len Holgate 4-Jul-02 22:49  Anonymous_com wrote: I've got an interface marshalled between different threads and I'd do it differently Len Holgate www.jetbyte.com The right code, right now.

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