Editing Mediator pattern (section)

===UML class and sequence diagram===

[[File:w3sDesign Mediator Design Pattern UML.jpg|frame|none|A sample UML class and sequence diagram for the mediator design pattern.<ref>{{cite web|title=The Mediator design pattern - Structure and Collaboration| url=http://w3sdesign.com/?gr=b05&ugr=struct |first=Günther |last=Franke |website=w3sDesign |access-date=2017-08-12}}</ref>]]

In the above [[UML]] [[class diagram]], the <code>Colleague1</code> and <code>Colleague2</code> classes do not refer to (and update) each other directly.
Instead, they refer to the common <code>Mediator</code> interface for controlling and coordinating interaction (<code>mediate()</code>), which makes them independent from one another with respect to how the interaction is carried out.
The <code>Mediator1</code> class implements the interaction between <code>Colleague1</code> and <code>Colleague2</code>.

The [[UML]] [[sequence diagram]] shows the run-time interactions. In this example, a <code>Mediator1</code> object 
mediates (controls and coordinates) the interaction between <code>Colleague1</code> and <code>Colleague2</code> objects.

Assuming that <code>Colleague1</code> wants to interact with <code>Colleague2</code> (to update/synchronize its state, for example), <code>Colleague1</code> calls <code>mediate(this)</code> on the <code>Mediator1</code> object, which gets the changed data from <code>Colleague1</code> and performs an <code>action2()</code> on <code>Colleague2</code>.

Thereafter,
<code>Colleague2</code> calls <code>mediate(this)</code> on the <code>Mediator1</code> object, which gets the changed data from <code>Colleague2</code> and performs an <code>action1()</code> on <code>Colleague1</code>.