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4/8/2010

State and Notifications Broker supports one type of state property: persistent state property. This type of state property has the same value both before and after device reset or shutdown.

All system state properties exposed by Windows Mobile software are stored in the registry at HKEY_CURRENT_USER\System\Stateand HKEY_LOCAL_MACHINE\System\Stateregistry keys. These are protected registry locations. Normal applications have read-only access to these locations.

You can create subkeys in HKEY_CURRENT_USER\Software\Stateor HKEY_LOCAL_MACHINE\Software\Stateto store non-system properties.

Conditional Notification

You can configure notifications to be sent only when the requested state property has changed to a desired value. This kind of comparison can be used to reduce the need to code conditional comparisons over a number of notifications into the client, and reduce message traffic.

Batch Mode Registration

You can configure notifications to work in batch mode for state properties that frequently change. State and Notifications Broker allows you to set a period of time for a state property value to stabilize before the State and Notifications Broker sends a change notification. The default time period is 200 milliseconds (ms) and there is no maximum time limit. You can set this time period in the registry. For more information, see RegistryBatchNotification.

Notification Types

The following table shows the notification types.

Type Description

Transient

Notification requests that are only valid while the client application is running. The request is lost when the device is reset or when the application is closed.

Persistent

Notification requests that remain valid after the device is reset or after the application is closed.

Notification Modes

The following table shows the notification modes.

Mode Description

Application activation

State and Notifications Broker starts a client application when a notification is sent. If the client is already running, State and Notifications Broker sends a message to the process window. For more information, see RegistryNotifyApp.

This mode applies only to persistent notifications.

Message Queue

State and Notifications Broker signals a registered client, by using a message queue, that a state property change has occurred. For more information, see RegistryNotifyMsgQueue.

This mode applies only to transient notifications.

Window message

State and Notifications Broker signals a registered client, by using a window message, that a state property change has occurred. For more information, see RegistryNotifyWindow.

This mode applies only to transient notifications.

Callback

State and Notifications Broker signals a registered client, by using a callback, that a state property change has occurred. For more information, see RegistryNotifyCallback.

This mode applies only to transient notifications.

See Also