Properly Implementing the Abstracy Factory Pattern

IAbstractFactory.cs

using System;

/// <summary>
/// An example abstract factory interface.
/// <para>The Abstract Factory pattern is a creational 
/// pattern, whose purpose is to provide an interface 
/// for creating families of related or dependent 
/// objects, without specifying their concrete 
/// classes.</para>
/// </summary>
public interface IAbstractFactory
{
    /// <summary>
    /// Creates an instance of IObjectA.
    /// </summary>
    /// <returns>An instance of IObjectA.</returns>
    IObjectA CreateInstanceA();

    /// <summary>
    /// Creates an instance of IObjectB.
    /// </summary>
    /// <returns>An instance of IObjectB.</returns>
    IObjectB CreateInstanceB();
}

IObjectA.cs

using System;

public interface IObjectA
{
    void DoWork();
}

IObjectB.cs

using System;

public interface IObjectB
{
    void DoWork();
}