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.NET Forum / .NET Framework / Interop / September 2005Refresh COM Object
Hi, I have a Vb6 DLL Called from csharp which is a report object. It can fetch data properly, however, when I run 2nd, 3rd, 4th time with differenct report criteria, the fetched data still remained as same as the first time. The object seems cannot refresh after first creation. It only refresh when I manually kill the process of aspnet_wp.exe How can I refresh the DLL object? Code to create the Object: Assembly asm = Assembly.LoadFrom("Lib.dll"); Type t = asm.GetTypes("Lib.CLib"); object o = Activator.CreateInstance(t); > Hi, > [quoted text clipped - 11 lines] > Type t = asm.GetTypes("Lib.CLib"); > object o = Activator.CreateInstance(t); This is no good idea. It is better to add a reference to the COM dll using Tlbimp.exe add a strong name to the interop assembly and add THAT assembly to your .NET project. Second, you create the instance to the VB6 class as follows Imagine, your VB6 class is called myObject myObjectClass myvb6Object = new myObjectClass(); forget to say, the DLL is generated from Tlbimp.exe >> Hi, >> [quoted text clipped - 23 lines] > > myObjectClass myvb6Object = new myObjectClass(); > forget to say, the DLL is generated from Tlbimp.exe > >>> Hi, >>> >> myObjectClass myvb6Object = new myObjectClass(); This is really the correct way to do it. What you did is called reflection. Isn't that overkill on COM objects? myObjectClass myvb6Object = new myObjectClass(); And try this as well to really release the com instance (because GC might delay the Release() of the com object, you need to dispose it manually) System.Runtime.InteropServices.Marshal.ReleaseComObject(o); Actually, I've tried put all COM objects to a collection and iterate and run ReleaseComObject() through the collection within a dispose method. The object call dispose() explicitly after generated the report. However, the report seems does not refresh at next load time. And I think the object still "hold" at memory. Any possible reason that cause this problem? >> forget to say, the DLL is generated from Tlbimp.exe >> [quoted text clipped - 11 lines] > > System.Runtime.InteropServices.Marshal.ReleaseComObject(o); > Actually, I've tried put all COM objects to a collection and iterate and > run ReleaseComObject() through the collection within a dispose method. The > object call dispose() explicitly after generated the report. However, the > report seems does not refresh at next load time. And I think the object > still "hold" at memory. Any possible reason that cause this problem? It looks like you compiled the VB project as single threaded. Each time you use the new keyword, you -should- retrieve a new class instance (just as with .NET classes). How VB fixes to be threadsafe is a long story, but a normal VB class that does not use module global variables should be fresh at ech new instance (using the new keyword). Since you are using reflection and an Activator, I don't know what's the difference between the new keyword and the activator, better be safe than sorry. Hi > I have a Vb6 DLL Called from csharp which is a report object. > It can fetch data properly, however, when I run 2nd, 3rd, 4th time with [quoted text clipped - 9 lines] > Type t = asm.GetTypes("Lib.CLib"); > object o = Activator.CreateInstance(t); You have to put <%@Page aspcompat="true" %> on the page that creates the COM object. Rob > Hi > [quoted text clipped - 14 lines] > You have to put <%@Page aspcompat="true" %> on the page that creates > the COM object. That is needed only for the VB6 class to function, if you use intrinsic objects from the Asp environment (such as response/session etc)... > Rob Hi Egbert, >>> I have a Vb6 DLL Called from csharp which is a report object. >>> It can fetch data properly, however, when I run 2nd, 3rd, 4th time [quoted text clipped - 16 lines] > That is needed only for the VB6 class to function, if you use intrinsic > objects from the Asp environment (such as response/session etc)... Aspcompat is needed for all apartment threading COM objects. W/out Aspcompat those objects will be created on a MTA thread, leading to failures and very bad performance, because the arguments of every method call will be marshaled. Rob
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