Allows operating system and third party app to launch your app with a file type or URI scheme. If there are multiple apps registered for same file type or URI, user will be presented with dialogue box to choose app. If there are no file or URI association, then user will sent to Windows Phone Store to download appropriate app. Any app can register a file or protocol association on Windows Phone 8 (WP8)
When using Internet Explorer, however, default system handler will be used regardless of registered association.
Allows for unidirectional communication between apps. For bi-directional app communication, register two different protocols.