Envoy Application Programming Manual

Table Of Contents
Software Concepts
Envoy Application Programming Manual427159-001
2-4
File-System Procedures
An application process functionally interacts with Envoy by way of:
Guardian 90 file-system procedures
Guardian 90 file-system error codes
Format of the message being transferred
The interrupt handler receives line interrupts from all configured asynchronous and byte-
synchronous communication lines and routes them to the proper I/O process.
File-System Procedures
The Guardian 90 file-system procedures that you can call to perform Envoy data
communications tasks are:
AWAITIO[X]
CANCEL
CANCELREQ
CHANGELIST
CLOSE
Figure 2-1. Application-Guardian 90-Envoy Relationship
007CDT .CDD
Application
Process
Guardian 90
User
Envoy
Envoy I/O
Process
Protocol
Procedure
Driver
Procedure
File-System
Procedures (OPEN,
CLOSE, READ,
WRITE, CONTROL,
and so forth)