C# COM Interop, try to access remote server gets access denied exception

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Hi,

I have a WPFApplication coded in c# that access a COM component. My machine(client) and the COM Server machine have Windows 7 OS. And both on same domain. I tried to create an instance of the com component with below code and it gave me no error

C#

IPDSIntf test; 
string clsId = "85689616-277B-4E00-9A5E-19AD78E7E0E2";
var type = Type.GetTypeFromCLSID(new Guid(clsId), MachineName, true);
                var COMObject = Activator.CreateInstance(type);
                test = (IPDSIntf)COMObject;

Now when I call any method in the COM. say test.Connect(clientId, errorCode), I am getting exception 'Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))'.

Have set many permission, gave admin privilege to my user account on the server machine, added mu account to 'Distributed COM Users' group etc... But still getting same issue.
If I have the COM component also locally, i.e. , client and server in same machine, I get no such error.

I am running out of time to fix it and have already spent 3 days on the same, googling. But no luck.

One more thing, is I could not see my COM in DCOMCNFG, means it is not registered? What could be the reason for it. I believe all COM component in machine will be registered in component services. Need some clarification on this too as I doubt it has some relation with my issue.

Thanks In advance,
Nishitha

Posted 6-Jun-12 0:48am

nairnishitha

Updated 6-Jun-12 19:43pm

v3

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2 solutions

Solution 1

Hi,

please have a look at my hints a few weeks ago, maybe it works for you.

Retrieve Operating system details of a remote computer using IP address[^]

Regards

Posted 6-Jun-12 1:33am

El_Codero

Comments

nairnishitha 6-Jun-12 8:30am

I have copied the code mentioned in above link and created a ManagementScope object(for the remote machine) and set privilege. It gave me no exception. But still my Connect() method is giving the very same error.

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barneyman · Accepted Answer · 2012-06-06T20:18:00

here's some code comments, I've referred to a LOT in recent years ;)

/*<br />
<br />
If you are reading this because you're trying to get a DCOM component working, and you're trying to establish why THIS one<br />
works, and yours doesn't, you've come to the right place ...<br />
<br />
Fundamentally, DCOM works thru the application of settings in the HKLM/APPID reg branch<br />
<br />
CLSIDs are connected to APPIDs thru the val APPID in the HKLM/CLSID branch<br />
<br />
When creating a ATL server object, be that exe, service or dll, the wizard for (at least vs2010) doesn't create all the right glue<br />
<br />
Additionally, running DCOMCNFG confuses the issue because *IT* creates glue in lieu of what ATL didn't, and gets it wrong<br />
<br />
You need to mod your object's RGS file to include<br />
                val AppID = s '%APPID%'<br />
<br />
You need to supplement your server's RGS to include<br />
                // for exes<br />
                NoRemove AppID<br />
                {<br />
                    '%APPID%' = s '<your description of your application>'<br />
                    '<your exe's name>.exe'<br />
                    {<br />
                        val AppID = s '%APPID%'<br />
                    }<br />
                }<br />
                // for dlls<br />
                NoRemove AppID<br />
                {<br />
                    '%APPID%' = s '<your description of your application>'<br />
                    {<br />
                        val DllSurrogate = s ''<br />
                    }<br />
                    '<your exe's name>.dll'<br />
                    {<br />
                        val AppID = s '%APPID%'<br />
                    }<br />
                }<br />
<br />
<br />
%APPID% is a known token in the RGS registrar mechanism<br />
<br />
NOW, you can use dcomcnfg to configure your object, and it should work<br />
<br />
errors you may get<br />
<br />
ACCESSDENIED - the user trying to launch the com object must be given launch permissions *AND* be included in the machine's Access Limit<br />
MISSINGMODULE - probably missing the proxyStub dll<br />
<br />
<br />
*/

Hope it helps