What -is Bearer Mobility

What -is Bearer MobilityThis topic describes the concept of Bearer Mobility in the -Communications Framework. -

Bearer Mobility is a feature that allows a device to change bearers without -interruption to the user's data sessions. An example of a bearer change is -if a device moves into the range of a Wi-Fi hot spot and the device moves -the GPRS connections over to Wi-Fi. Example data sessions include: streaming -videos; surfing the internet; and downloading emails. Example bearers include: -Wireless LAN (eg Wi-Fi); 3G (including HSUPA and HSDPA); Circuit Switched -Data (CSD); and GPRS.

- - Example of a bearer change -

A device is connected to a mobile network using GPRS. The device -comes into range of a Wi-Fi network. The device decides to change to the Wi-Fi -network and creates a bearer to access the Wi-Fi network. The device then -moves all the existing connections across to the Wi-Fi bearer. In the final -step the device disconnects from the GPRS network.

- - -

Bearer Mobility operates in response to changes in the environment of the -device. A bearer is known as available when the device is in range -of the bearer and the device can potentially use the bearer.

NOTE: The bearer can be available but unusable because of the security -requirements of the bearer.

Symbian platform uses non-seamless Bearer Mobility. Non-seamless -indicates that clients of the Socket Server must reconnect all sockets after -the bearer has changed. The local IP address of the link changes if the bearer -changes.

Bearer Mobility APIs

Two Socket Server Bearer Mobility -APIs are available: RCommsMobilityApiExt and CActiveCommsMobilityApiExt. -A client of the Socket Server cannot change bearer if the client does not -use at least one Bearer Mobility API. A device can have clients that support -Bearer Mobility and clients that do not support Bearer Mobility. If clients -that support Bearer Mobility change bearer, the device does not disconnect -a client that does not support Bearer Mobility unless that client's bearer -is no longer available.

A client of the socket server can ask the -user to accept or deny the change of bearer. For example, the client can display -a dialog box to ask the user to accept or deny the change. The decision to -ask the user remains with the client.

A client of the socket server -can ask to use the default bearer. The default bearer is the highest priority -bearer that is available. The device manufacturer or network operator creates -the list of bearer priorities.

Bearer Mobility -Blacklists

The Bearer Mobility components in the Communications -Architecture implement a blacklist feature. The Socket Server implements -the blacklist feature on the server side. The blacklist feature affects the -notifications that a Socket Server client receives. The blacklist feature -stops notifications for bearer changes that have previously been rejected. -The device keeps a blacklist for each client.

For example:

A client receives a -notification for a bearer change
The client sends a response -to reject the bearer change
The device adds the -rejected bearer to the blacklist for that client
The device does not -notify the client of any further opportunities to change to that bearer

There can be variations in the operation of the blacklist. For example, -there can be a limit on the lifetime of the blacklist.

NOTE: The -blacklist scheme is dependent on the plug-ins and settings used for the Communications -Architecture for the particular device.

-Using the - Bearer Mobility APIs + + + + + +What +is Bearer MobilityThis topic describes the concept of Bearer Mobility in the +Communications Framework. +

Bearer Mobility is a feature that allows a device to change bearers without +interruption to the user's data sessions. An example of a bearer change is +if a device moves into the range of a Wi-Fi hot spot and the device moves +the GPRS connections over to Wi-Fi. Example data sessions include: streaming +videos; surfing the internet; and downloading emails. Example bearers include: +Wireless LAN (eg Wi-Fi); 3G (including HSUPA and HSDPA); Circuit Switched +Data (CSD); and GPRS.

+ + Example of a bearer change +

A device is connected to a mobile network using GPRS. The device +comes into range of a Wi-Fi network. The device decides to change to the Wi-Fi +network and creates a bearer to access the Wi-Fi network. The device then +moves all the existing connections across to the Wi-Fi bearer. In the final +step the device disconnects from the GPRS network.

+ + +

Bearer Mobility operates in response to changes in the environment of the +device. A bearer is known as available when the device is in range +of the bearer and the device can potentially use the bearer.

NOTE: The bearer can be available but unusable because of the security +requirements of the bearer.

Symbian platform uses non-seamless Bearer Mobility. Non-seamless +indicates that clients of the Socket Server must reconnect all sockets after +the bearer has changed. The local IP address of the link changes if the bearer +changes.

Bearer Mobility APIs

Two Socket Server Bearer Mobility +APIs are available: RCommsMobilityApiExt and CActiveCommsMobilityApiExt. +A client of the Socket Server cannot change bearer if the client does not +use at least one Bearer Mobility API. A device can have clients that support +Bearer Mobility and clients that do not support Bearer Mobility. If clients +that support Bearer Mobility change bearer, the device does not disconnect +a client that does not support Bearer Mobility unless that client's bearer +is no longer available.

A client of the socket server can ask the +user to accept or deny the change of bearer. For example, the client can display +a dialog box to ask the user to accept or deny the change. The decision to +ask the user remains with the client.

A client of the socket server +can ask to use the default bearer. The default bearer is the highest priority +bearer that is available. The device manufacturer or network operator creates +the list of bearer priorities.

Bearer Mobility +Blacklists

The Bearer Mobility components in the Communications +Architecture implement a blacklist feature. The Socket Server implements +the blacklist feature on the server side. The blacklist feature affects the +notifications that a Socket Server client receives. The blacklist feature +stops notifications for bearer changes that have previously been rejected. +The device keeps a blacklist for each client.

For example:

A client receives a +notification for a bearer change
The client sends a response +to reject the bearer change
The device adds the +rejected bearer to the blacklist for that client
The device does not +notify the client of any further opportunities to change to that bearer

There can be variations in the operation of the blacklist. For example, +there can be a limit on the lifetime of the blacklist.

NOTE: The +blacklist scheme is dependent on the plug-ins and settings used for the Communications +Architecture for the particular device.

+Using the + Bearer Mobility APIs

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