Worth Data 802 RF ユーザーズマニュアル

6-2

Methods are how you initiate communication with the WD802Term object. 
You can request that a prompt be sent to a terminal, map a terminal ID to an 
IP address, and a variety of other services. 

Events are how the WD802Term object initiates communication with your 
application. You write "event handlers" in your program to respond that 
respond appropriately when WD802Term "fires" an event that activates its 
associated event handler. Examples are OnTermSignIn and OnTermData.  

Creation of the source code "shell" for an event handler is generally handled 
by your development environment (IDE for Integrated Development 
Environment). For example, in Delphi, simply double click in an event field 
in the Object Inspector; or in VB, from the source code window, select the 
Object from the pull down list at the top left and then click on the desired 
event in the Procedures pull down list at the top right. 

You will notice that the IDE creates a "skeleton" function (or procedure or 
sub) in source code that will include any parameters required to retrieve the 
data delivered to the event handler by the WD802Term object. 

It is your job to add functionality to the skeleton event handler that is 
relevant to your application. It is important to remember to keep event 
handlers short and efficient. Do not make method calls to WD802Term 
from within a WD802Term event handler. Instead set up a state 
management and polling or threading scheme as outlined below. 

 

When a terminal 

, it sends a signal to your application via the 

WD802Term object, which fires the OnTermSignIn event. When the event 
fires, the terminal has already been assigned an ID number by WD802Term 
and this ID number is passed to your application in the event handler. 

Once it has signed in, the terminal is now waiting for your application to 
make a call to one of WD802Term's methods that sends a prompt to the 
terminal. Keep in mind that it is important to keep event handlers short and 
to try to avoid making method calls from inside an event handler. This 
brings us to transactions, state management, and data structures 

Generally, you will have some kind of 

transaction process that you will 

define. Typically a transaction would be defined by a series of prompts and 
the data returned in response to the prompts.  

Here is an example of a series of prompts that represent a transaction. When 
a transaction is completed, it repeats as controlled by the host application