- Hewlett-Packard Printer User Guide

Using the VPO Application Programming Interfaces
The VPO Interfaces
Chapter 4184
Overview of the Application Response Interface
The Application Response Interface enables an external application
to register for and receive Application Responses from VPO
applications that have been started by the Application API opcappl_
start(). VPO generates an application response whenever the status of
a running application changes.
Access to Action Responses
The Application Response Interface (OPCSVIF_APPLIC_RESPONSE) works
in a similar way to the Message Events Interface (OPCSVIF_MSG_
EVENTS). When an application registers for application responses, a
queue is opened to which the application responses are written. The
function opcif_read() reads the application responses from this queue,
see Figure 4-8 on page 187.