Endpoint Interface

Using the Endpoint Interface

Receiving Data Using Input Specs

23

The most common way to receive data is to use input specs. An input spec is a
frame that defines what kind of data you are looking for, termination conditions
that control when the input should be stopped, and callback methods to notify you
when input is stopped or other conditions occur.

An input spec consists of many pieces. It contains slots that define

the type of data expected (

form

slot)

the input target for template and binary data (

target

slot)

the data termination conditions (

termination

slot)

protocol flags for receiving data (

rcvFlags

slot)

an inactivity time-out (

reqTimeout

slot)

the data filter options (

filter

slot)

the options associated with the receive request (

rcvOptions

slot)

a method to be called when the termination conditions are met
(

InputScript

method)

a method to be called periodically to check input as it accumulates
(

PartialScript

method,

partialFrequency

slot)

a method to be called if the input spec terminates unexpectedly
(

CompletionScript

method)

Table 23-2 summarizes the various input data forms and the input spec slots that
are applicable to them. Input spec slots not included in the table apply to all data
forms. For more details on the input spec frame, see "Input Spec Frame"
(page 20-11) in Newton Programmer's Reference.

After you've connected or accepted a connection, you set up your first input spec
by calling

SetInputSpec

. When one input spec terminates, the system

automatically posts another input spec for you when the

InputScript

method

defined in the previous input spec returns. This new input spec duplicates the
one that just terminated. If you don't want this to happen, you can call the

SetInputSpec

method from within the

InputScript

method of your input

spec to change the input spec or terminate the input. Pass

nil

to

SetInputSpec

to terminate the input.

You also use the

SetInputSpec

method if you need to set up an input spec at

some other point. Note that if you want to terminate a current input spec to set up a
new one, you must call the

Cancel

method before calling

SetInputSpec

with

your new spec. (This applies inside an

InputScript

that is called as a result of

calling the

Input

method.)