Windows 8 app developers have some new tools to work with when they make their Metro style software products. One of them is called contracts. Basically, putting in contracts in Windows 8 apps allows them to interact with other apps or with Windows 8 itself.
In a new and highly technical entry on the Windows 8 app developers blog site, Microsoft's Derek Gebhard writes about how app developers can program and use Windows 8 contracts in their apps. Gebhard gives a couple of examples of how these contracts work:
For example, the File Open Picker contract allows the user to import files from one app into another. With the Search contract, users are empowered to search an app from anywhere in the system and can quickly transfer a query between multiple apps. In all of these cases, and a lot of other contract scenarios, Windows needs to be able to launch directly to a spot in your app’s UI where the user can complete a specific task quickly and efficiently.
He also says that even if a Windows 8 Metro app maker doesn't add support for contracts in his app at first, it's still a good idea to keep these techniques in mind, saying, "This way you can easily extend your app in the future to support contracts without refactoring your code."
Image via Microsoft