In my C# library I have an interface which exposes set of method to the consuming class.

Now my class need to raise some events. I was thinking to embed the event definition in my interface only so that client can register easily.

So I have this definition:

```
public delegate void EventCallBack(object sender, EventArgs eventData);

```

And my interface contains this line:

```
EventCallBack NotifyListener;

```

Now I am getting following error:

> 
> Interface cannot contain definition
> 
> 
> 

How do I incorporate my event definition in interface only?