AML KDT750 Price Verification System - Manual (Page 11)

KDT750 APL Guide
2 - 2
Transaction Overview
APL is a packet based, connection oriented protocol. For each lookup to the server, a new
connection is created, the request made, a reply sent and the connection destroyed.
Figure 2.1 - Typical AP Transaction
General Data Format
APL defines all messages between two devices as item/value pairs. Item/value pairs are a
collection of bytes defining a variable's name and its associated data, and are used to
communicate a variety of different actions, commands, and information between the host
and client.
Normally, the item name is separated from the value data by a standard ASCII equals (”=”)
sign. Data to the left of the equals sign is defined as the item's or action's name, whereas to
the right of the equals sign is defined as the value. The 'ITEM=VALUE' pair is normally ASCII
encoded, but depending upon the implementation, some characters may be required to
be encoded in a different format.
Here, the data is named “BAR”, and its value is “1234567890”: