Transport Interface

Using the Transport Interface

for the item. This allows the transport an opportunity to add its own slots to the
item frame.

Most transports will want to add a

fromRef

slot to the item frame. This slot must

contain a name reference that identifies the sender. This information is usually
extracted from the sender's current owner card, or persona. You shouldn't just use
the value of

GetUserConfig('currentPersona)

because it is simply an alias

to a names file entry. Instead, construct a name reference from this value. For example:

persona := GetUserConfig('currentPersona);
dataDef := GetDataDefs(addressingClass);
fromRef := dataDef:MakeNameRef(persona,addressingClass);

Most transports will want to extract and send only the needed information from the

fromRef

name reference. For example, an e-mail transport would typically just

extract the sender name and e-mail address from the name reference and send them
as strings. One method of name reference data definitions that you can use to
extract useful information from a name card includes

GetRoutingInfo

. Here is

an example of using this method:

// extract just routing info using GetRoutingInfo
routeInfo:= datadef:GetRoutingInfo(fromRef);
// returns an array like this:
[{name: "Chris Smith", email: "cbsmith@apple.test.com"}]

The

GetRoutingInfo

method returns an array of at least one frame that has at

least a

name

slot containing a string. Depending on the

addressingClass

slot

passed to the

GetDataDefs

function, the returned frame also contains other

information particular to the type of address used for the transport. In the example
above, the frame also contains an

email

slot with an e-mail address.

If you want to add other slots to the

fromRef

frame, you can either define your

own name reference data definition and override the method

GetItemRoutingFrame

(called by

GetRoutingInfo

), or add the slots you

want to the

fromRef

frame by extracting them from the original name reference

with the

Get

method. For example:

// use Get to extract info from certain slots
fromRef.myInfo := dataDef:Get(fromRef,'myInfo,nil);

Note that a sender may have multiple e-mail addresses and the transport should set
the e-mail address in the

fromRef

frame to the one that is appropriate to itself. For

example, for an internet e-mail transport, you would typically set the

fromRef