Iguana plugins that use the old VB.NET/C# interface communicate with Iguana using the following communication libraries that are included with the Iguana installation:

• IGC.dll
• IGC_csharp.dll

IGC.dll is a native dynamic link library that implements the Iguana plugin communication protocol, and should not be distributed with the plugin. Instead, the PATH environment variable should include the full path of the directory that contains IGC.dll, which is the directory in which Iguana is installed (for example, C:\Program Files\iNTERFACEWARE\Iguana).

	If you have created a 32-bit plugin to interface with 32-bit Iguana and you upgrade to the 64-bit version of Iguana, be sure to save a copy of the 32-bit version of IGC.dll and ensure that your 32-bit plugin refers to it. This will allow you to continue using your 32-bit plugin with 64-bit Iguana. A 32-bit plugin will not work with the 64-bit version of IGC.dll that is included with the 64-bit version of Iguana.

IGC_csharp.dll is a .NET assembly that wraps IGC.dll and provides a .NET interface to the Iguana plugin communication protocol. This assembly is used by C# and VB.NET plugins to communicate with Iguana. It is located in the plugins subdirectory of the directory in which Iguana is installed. It should be distributed with, and installed in, the same folder as the plugin.

For more information on the API that is defined to enable plugins to communicate with the IGC.dll dynamic link library, see the C# IGC (Iguana Client) Class Reference.

	In C# or VB.NET, the IGC.dll entry points are loaded dynamically when a plugin first uses them. If the entry point is missing, which would happen if an old version of IGC.dll is accessed, a System.EntryPointNotFound exception is thrown. The error message for the exception will be similar to the following: Unable to find an entry point named _IGCmessageRequestResponseSetStopChannel@8 in DLL IGC. If IGC.dll cannot be found, a message similar to the following appears: Unable to load DLL 'IGC': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

	The Iguana communication libraries employ a multi-threading model. This means that you can create a multi-instance plugin, which is a single plugin process that is concurrently running multiple plugin instances. For best results, use single-instance plugins unless absolutely necessary. You should only use a multiple-instance plugin if it provides a clear benefit and if you can successfully deal with the complexity that is imposed when the multiple-instance model is introduced.