Hi,
I am beginner of OO Design. Recently I read some article about mediator, bridge and etc pattern.
I would like to develop my own classes using these pattern.
Now, I have some unclear question. If I have two classes designed using mediator pattern whcih used to control my client application. How both services should interact with each other if one of them need to call a particular method of other service on certain situation. And it may let some flexibility for future if i would liek to add more services? Should I have a application kind of object or...?

Please advise