Integrating with the Windows 8 environment - Build Windows 8 Apps with HTML5 and JavaScript - page 205

Contract Description

The application implements this contract to let users access customizable application
settings that affect the way in which users interact with the application. Windows 8
requires that applications expose settings in a standard way that passes through the
implementation of the Settings contract.

Settings

The application implements this contract to let user search within any content
application-specific content that may be available.

Search

The application implements this contract to enable users to easily stream audio, video, or
images from their computer to any connected devices in their home network (such as, a
large TV screen).

Play to

The application implements this contract if it is providing customized access to files and
folders (via the File picker provider contract) and needs to notify applications of detected
changes to listed files and folders.

Cache updater

As you can see, not all of the supported contracts make sense for just any Windows Store
application. For example, Share and Settings contracts are much more common than the Play to
contract or the Cache updater . Yet, the Windows 8 framework does provide a large offering of
customizable aspects that is not even limited to contracts.

extensions
While contracts are about agreements set between applications, extensions relate to agreements
set between an application and the Windows operating system. By registering an extension, the
application intends to extend or customize one or more standard Windows features such as, for
example, the way in which files with a given extension (such as, TXT files) are managed within the
operating system. Table 9-2 lists extensions available in Windows 8.

TABLE 9-2 Extensions available for Windows Store applications

Extension Description

Account picture provider The application provides this extension to be listed in the Account Picture Settings

control panel as an application which can provide a picture for the user account.

AutoPlay provider The application provides this extension to be listed as an AutoPlay choice for the one or

more AutoPlay events. Windows fires the AutoPlay event whenever the user connects a
device to the computer.

Background task provider The application provides this extension if it needs to do some work in the background

when the application is suspended. Background tasks are intended to be small work
items that require no interaction with the user.

Camera settings provider The application provides this extension if it can provide a custom user interface for

selecting camera options and choosing effects when a camera is used to capture a
photo or video.

Contact provider The application provides this extension to be included in the list of applications that

Windows displays whenever the user needs to pick a contact.

File activation provider The application provides this extension if it intends to register as the handler of files

with a given extension.

Print settings provider The application provides this extension if it can provide a custom user interface for

selecting printer options.