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Implementing Interface using Reflection c#

I have a requirement where I need to implement an interface in my project which is present in a third part DLL. I'm loading this DLL using reflection. Is it Possible?
class MyClass : I3rdPartyInterface
{
//implementing interface
}
Here, the I3rdPartyInterface is the interface present in my 3rd Party DLL.
This DLL could, or could not, be present on Client machine my software product is installed. If it is present, then i should implement the interface methods.

Your best option is to write a new project that references that dll and implements the interface - and load that in runtime.
The new dll "translates" between the external dll types and your application's types - that way there is no direct dependency between your app and the external dll.
You can generate and compile code at runtime but for this scenario it's just simpler to create a wrapper/translator dll

Access .net dll through JNA in java

I have a .net 4.0 dll it has a namespace and in that namespace there is a class, I wants to access procedures inside that class using jna.
I have included jna.jar as well as platform.jar(in case) using maven,
My java code looks like this
MyConfiguration interface
import com.sun.jna.Library;
public interface MyConfiguration extends Library{
public void callInterface();
}
Accessing dll code
MyConfiguration myAPI = (MyConfiguration) Native
.loadLibrary("dll/MyAPI.dll", MyConfiguration.class);
System.out.println("Interface Created");
System.out.println("Calling Interface");
myAPI.callInterface();
but i am getting the exception--->
Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'myInterface': The specified procedure could not be found.
at com.sun.jna.Function.<init>(Function.java:208)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:536)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:513)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:499)
at com.sun.jna.Library$Handler.invoke(Library.java:199)
at com.sun.proxy.$Proxy0.myInterface(Unknown Source)
at foo.App.main(App.java:83)
I have checked the dll using dll decompiler tool, and it has the called function, can somebody help out.

dll using dll decompiler tool
You need to use a PE (portable executable) viewer to look for entries in the export table. (Depends is one.)
Most .NET DLLs don't export functions that way. When they do, it's through a mechanism called Reverse P/Invoke, which isn't supported by most Microsoft .NET language compilers. The C++/CLI language was designed for this purpose.
You might find a shorter path to success with a Java-.NET bridge product. Or, a Java-COM bridge product if the .NET DLL exposes classes as COM objects. (Use OLE/COM Object Viewer to inspect a COM DLL.)
Also, be sure the DLL has the same bitness as your JVM process (e.g., java.exe or javaw.exe), unless you are using as an out-of-process COM object.

Creating a simple c# dll and access it from ruby

I'm trying to make my first c# dll.
I want to be able to call it's methods/functions from ruby with win32API.
I have made this dll:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ClassLibrary1
{
public class Class1
{
public int PropA = 10;
public void Multiply(Int32 myFactor)
{
PropA *= myFactor;
}
}
}
I compiled it with Visual Studio 2010 and got my ClassLibrary1.dll file.
Now for the ruby part i tried this:
f = "c:/path_to_file/ClassLibrary1.dll"
mult = Win32API.new(f,"Multiply",["I"],"I")
But, i get the following error:
Error: #<RuntimeError: (eval):0:in `initialize': GetProcAddress: Multiply or MultiplyA
To be honest, I never created a dll, nor do I have experience with c#. I just wanted to get started. I have used many dll's with Ruby via win32API before (user32 mostly).
I guess my dll is not ok?
Regards,

To consume functions from DLLs as done in a Win32 context, these functions need to be export-visible from the DLL. These functions are usually flagged with dllexport and will show up in the export table of a DLL. You can verify that user32 and other Win32 DLLs do this by using a utility such as dumpbin (MSDN).
dllexport, dllimport # MSDN
Unfortunately, .NET doesn't have immediate support for making functions export-visible, only for bringing in such functions via the DllImport (MSDN) Attribute.
COM is the easiest way to consume code written within .NET from a non-.NET environment, but if you must use the lower level bindings, you can make an intermediate DLL in C, C++/CLI, or any other language and framework combination that can write export headers to a dll, to call your .NET code.
Also, A few articles exist on making this happen via post-compilation automation or other workarounds, here are a few for your reference.
How to Automate Exporting .NET Function to Unmanaged Programs # CodeProject
Unmanaged Exports # Google Sites
DllExport - Provides C-style exports for pure .NET assemblies

Without doing anything extra, the DLL created is an Assmebly intended to be run inside the .Net runtime (the CLR).
You can expose it through Com as described in the related question: Can Ruby import a .NET dll? which

c# about interfaces

I have a library that contains some public interfaces. Before each public interface there is a: [Guid:("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxx")]. What is this Guid. what does it do? Is it possible to acces the methods from this library without adding the lib to ref just using this Guid. Or what can i do using another application with this Guid?

This GUID is used when the .NET assembly is used as an COM object. You can't use this method without referencing either the .NET assembly as a .NET assembly or as a COM object. This is mainly for interoperability with other languages that don't know how to work with .NET assemblies. COM objects can be consumed by virtually any technology/language on Windows.

How to deploy a COM

I just finished building my new COM project (C#, .NET 3.5). This project will be called by a VFP application. It's working great on my development machine, but now I need to know how to deploy it on the user's machine. Click Once isn't available for this kind of project, so I guess I'm stuck with manually distributing the DLL.
So, where should I put the DLL and how do I register it?
BTW, the 3.5 framework is already installed on the user's machine.
TIA

I've really never used RegSvr32 with .Net assemblies, rather I use the regasm with the /codebase option:
C:\Windows\Microsoft.NET\Framework\v2.0.50727\regasm.exe /codebase mydll.dll
You can also use the /tlb option to export the type library and register it.
Of course the easiest way, just create an installer with vstudio and it will do this for you.

Creating a Description of the COM class and Interfaces
.Net assemblies don't include information in Type Library compatible format. So it is necessary for the programmer to run one of two .Net-supplied utilities to extract the assembly description of a class into a Type Library file.
One utility is TLBEXP.EXE, the .Net Type Library Exporter. This command line utility takes as input the name of an assembly DLL file to be converted to a Type Library. The programmer can also specify the name of a Type Library file to be created.
tlbexp ComServer.dll /out:ComServer.tlb
Assembly exported to C:\Magellan\Source\Output\Debug\ComServer.tlb
Once a Type Library has been created, it can be referenced by a COM client to obtain the information necessary for the COM client to bind to the interfaces of the COM class, and activate the COM class at runtime.
Registration of the COM Class and Interfaces
For a COM class to be accessible by the client at runtime, the COM infrastructure must know how to locate the code that implements the COM class. The following command accomplishes this:
regasm ComServer.dll
Your DLL can be put anywhere you wish, but a good choice is C:\Program Files\MyApplication.
http://www.csharphelp.com/archives/archive190.html