How to call methods from COM object (cannot cast System.__ComObject to my COM class)

Question

I can create COM object locally

var infsrv = new InfoServ.TInfoServerClass(); //COM object
infsrv.RunBsScript(bssScriptName, strOfParam); //calling method

But I needed to create COM object on server, so code is:

var myGuid = new Guid("00C4261D-0B2B-4230-A2CA-A9F4F2A46452");
var myType = Type.GetTypeFromCLSID(myGuid, servername);
InfoServ.TInfoServerClass infsrv = (InfoServ.TInfoServerClass)Activator.CreateInstance(myType);
infsrv.RunBsScript(bssScriptName, strOfParam);

but now it says:

Unable to cast COM object of type 'System.__ComObject' to class type 'InfoServ.TInfoServerClass'. COM components that enter the CLR and do not support IProvideClassInfo or that do not have any interop assembly registered will be wrapped in the __ComObject type. Instances of this type cannot be cast to any other class; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.

what should I do?

Andy Hopper · Accepted Answer · 2012-03-05 18:47:05Z

2

You should be able to cast the instance created by the call to Activator.CreateInstance to an interface.

You should have an interface defined in the Interop assembly named InfoServ.TInfoServer (or ITInfoServer if the type library explicitly defined an interface for it), and if you cast the object returned by Activator.CreateInstance to that interface, you should see all of the methods/properties the CoClass (TInfoServerClass) exposes.

answered Mar 5, 2012 at 18:47

Andy Hopper

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Comments

Thorsten Dittmar · Accepted Answer · 2012-03-05 13:42:33Z

0

Usually you use the "Add Reference" dialog to add a reference to a COM library. Then you can use the imported types like you would use any other class.

answered Mar 5, 2012 at 13:42

Thorsten Dittmar

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