COM object Interface issue

Question

User-1087976105 posted

Hello all

I'll start off by saying I'm a bit of a noob with ASP.NET  I do know a bit of vb from the old days though.

Using Visual Web Developer 2008 express I've written a dll in vb.net that interfaces with another COM dll called CybersourceWSLib

In my class, called cybersource I interact with a few of the Interfaces inside the CybersourceWSLib COM dll.

My problem is that when I attempt to use one of the properties of the interface from my web page like so:

Imports Cybersource.cyber1.cyb
Partial Class registration
    Inherits System.Web.UI.Page
    Private Shared oCyb As New Cybersource.cyber1.cyb
<snip>
       oCyb.EnableLog = "0"

I get:

"System.NullReferenceException: Object reference not set to an instance of an object."

I've declared the interfaces inside the dll but I'm guessing they are not initailized???  I dunno

Here is where I declare them in the class inside my vb.net dll

Namespace cyber1

    Public Class Cyb

        Private Shared objMerchConfig As CyberSourceWSLib.IMerchantConfig

        Private Shared oRequest As New System.Collections.Hashtable

        Private Shared oReply As New System.Collections.Hashtable

        Private Shared oClient As CyberSourceWSLib.IClient

My web page access the properties in my dll through :

Public Shared Property LogDirectory() As String
            Get
                Return objMerchConfig.LogDirectory
            End Get
            Set(ByVal value As String)
                objMerchConfig.LogDirectory = value
            End Set
End Property

That is when I get the error.

What do I need to do to make this work.

Answer 1

User116058376 posted

Hi Russ,

You are correct, the intialization is the problem here. use any reflectors like Lutz Roeder's .NET Reflector

to find out what are the methods available in the com object and try to use initialize the object before using the properties.

Answer 2

User-1087976105 posted

Thanks for the reply

I thought so.  Now How would I actually initialized them?

Doing a x As New interface  generates an error.

Answer 3

User-952121411 posted

Did you get this solved here on your other thread which appears to be the same issue:

http://forums.asp.net/p/1468080/3393167.aspx

If not, I reccomend getting the API documentation from Cybersource and looking at thier code examples.  I have done something similar with PayPal before, and you can look at their documentation to see best how to use their exposed .dll.

As a last resort you can use that reflection tool offered previously, but it would be odd that CyberSource does not offer some sort of documentation or support for their provided .dll. 

There are some great support links for developers on the CyberSource site which you should look into if you have not already:

http://www.cybersource.com/support_center/implementation/downloads/

http://apps.cybersource.com/library/documentation/sbc/api_guide/html/