RuleClasses for Event Based Rule Engine

RuleClasses.cs

public delegate void RuleEventHandler(object sender, RuleEventArgs e);

public class RuleEventArgs
    : EventArgs
{
    public RuleEventArgs()
        : base()
    { }
}

public interface IRule
{
    void Execute();
    //void Execute(object sender, RuleEventArgs e);

    bool RuleCondition();

    event RuleEventHandler BeginExecution;
    void OnBeginExecution(object sender);

    event RuleEventHandler EndExecution;
    void OnEndExecution(object sender);

    event RuleEventHandler PassedRule;
    void OnPassedRule(object sender);

    event RuleEventHandler FailedRule;
    void OnFailedRule(object sender);
}

public abstract class BaseRule
    : IRule
{
    private string rulename;
    public string RuleName
    {
        get { return rulename; }
    }

    // Payment object(FACT) to use in RuleCondition method
    public readonly IEntity _payment;
    public BaseRule(string rulename, IEntity payment)
    {
        this.rulename = rulename;
        this._payment = payment;
    }


    //public virtual void Execute();
    //public virtual void Execute(object sender, RuleEventArgs e);
    public virtual bool RuleCondition()
    {
        throw new NullReferenceException();
    }

    public virtual void Execute()
    {
        OnBeginExecution(this);

        if (RuleCondition())
            OnPassedRule(this);
        else OnFailedRule(this);

        OnEndExecution(this);
    }

    public event RuleEventHandler BeginExecution;
    public void OnBeginExecution(object sender)
    {
        if (BeginExecution != null)
            BeginExecution(sender, new RuleEventArgs());
    }

    public event RuleEventHandler EndExecution;
    public void OnEndExecution(object sender)
    {
        if (EndExecution != null)
            EndExecution(sender, new RuleEventArgs());
    }

    public event RuleEventHandler PassedRule;
    public void OnPassedRule(object sender)
    {
        if (PassedRule != null)
            PassedRule(sender, new RuleEventArgs());
    }

    public event RuleEventHandler FailedRule;
    public void OnFailedRule(object sender)
    {
        if (FailedRule != null)
            FailedRule(sender, new RuleEventArgs());
    }

}