Question

I’m currently developing a application where I will have multiple windows open using C# and WPF.

Is there a pattern or common methodology used to help faciliate communication between open Windows or/and UserControls?

For example, a window, let’s call it the ‘Hierarchy Window’, may displays a hierarchy of countries, provinces, and cities in the world. Outside of that there are several other Windows which may display a province or city for example OR allow you to create a province or city. In the case of creating a new city, which is the best way for my ‘City Window’ to communicate with my ‘Hierarachy Window’ regarding adding a city or removing a city?

Keeping in mind that the ‘Hierarchy Window’ might not even be open when a City is created. At which point, there is no need for a response/action.

Answer 1

There are two common approaches to this:

1. Use Dependency Injection to inject a common service.
2. Use a messenger of some form.

The second option is becoming very popular with WPF and Silverlight. Many common toolkits, such as MVVM Light (for details, see the Messenger class description), use this approach.