Transport Interface

Using the Transport Interface

For example, the built-in Print transport uses the

protoTransportPrefs

proto

for its preferences view. Since the

ReceiveRequest

method does not exist in

the Print transport, the In Box preference element is not displayed, as shown in
Figure 22-10.

Print preferences

The Info button is included in the

protoTransportPrefs

template so you can

give the user access to About and Help views for the transport. The button is built
from the standard

protoInfoButton

proto. To include items on the Info picker,

you must provide handler methods in the

infoPrefs

slot of your transport

preferences view. The

protoTransportPrefs

template includes a handler for

the "Help" item that displays the system help book, open to the routing section.
You'll need to override this method if you want to provide your own help information.

You can add custom items to the Info picker by supplying

GenInfoAuxItems

and

DoInfoAux

methods in the

infoPrefs

frame. For more information about

these methods and how the Info button works, see "protoInfoButton" (page 6-10)
in Newton Programmer's Reference.

The

defaultConfiguration

slot in the

protoTransport

holds the initial

preferences associated with the transport. This slot is set up by default with a frame
holding an initial selection of preferences items. The child views of the

protoTransportPrefs

proto are designed to manipulate the slots in this frame.

If you want to override the default preferences frame, you need to construct an
identical one with different values. You can't use a

_proto

slot in your default

frame since the contents of the

defaultConfiguration

slot are stored in a

soup and

_proto

slots can't be stored in soup entries.