Establishing a connection 23, Sending data 23 – Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) User Manual

Page 839

C H A P T E R 2 3

Endpoint Interface

Using the Endpoint Interface

23-11

When you are finished with an endpoint, you must unbind it using the

UnBind

method, then dispose of it using the

Dispose

method.

Establishing a Connection

After instantiating and binding an endpoint, you establish a connection.

There are two ways you can create a connection. One way is to call the

Connect

method. If the physical connection is serial, for instance, you don't even need to
specify an address as an option. The

Connect

method immediately establishes

communication with whatever is at the other end of the line.

Certain communication tools—for example, the modem and AppleTalk tools—
require you to specify an option of type

'address

in order to make a connection.

The modem tool requires a phone number as an

'address

option. You should

use the global function

MakePhoneOption

to return a proper phone number

'address

option. The AppleTalk tool requires an AppleTalk Name Binding

Protocol (NBP)

'address

option. You should use the global function

MakeAppleTalkOption

to return a proper NBP

'address

option.

To establish a connection where you expect someone else to initiate the connection,
you need to call the

Listen

method. Once the connection is made by using

Listen

, you need to call the

method to accept the connection, or the

Disconnect

method to reject the connection and disconnect.

Sending Data

To send data, use the

Output

method. This method is intelligent enough to figure

out the type of data you're sending and to convert it appropriately for transmission.
This is because NewtonScript objects have type information embedded in their
values, allowing the system to select appropriate default data forms for different
kinds of data being sent.

You can specify output options and a callback method by defining an output spec,
which you pass as a parameter to the

Output

method.

Certain communication tools may require or support the use of special flags
indicating that particular protocols are in use. For example, the built-in infrared and
AppleTalk tools expect framed (or packetized) data, and there are special flags to
indicate that this kind of protocol is in use. If you are using such a communication
tool to send data, you need to specify the

sendFlags

slot in the output spec

frame. In this slot, you specify one or more flag constants added together.

To send packetized data, you set

sendFlags

kPacket+kMore

for each packet

of data that is not the last packet. For the last packet, set

sendFlags

kPacket+kEOP