EVRs Introduction

AIT provides support for YAML-based configuration of Event Verification Records (EVRs) within the system. Below is an example of a simple set of EVRs defined for use in the toolkit.

- !EVR
  name: NO_ERROR
  code: 0x0001
  desc: No error
  message: "No error"

- !EVR
  name: EVR_1
  code: 0x0002
  desc: EVR 1
  message: "The first evr"

- !EVR
  name: EVR_2
  code: 0x0003
  desc: EVR 2
  message: "The second evr"

- !EVR
  name: EVR_3
  code: 0x0004
  desc: EVR 3
  message: "The third evr %s"

Message Formatting

AIT EVRs allow you to include common format strings in the message attribute so that EVR data can be decoded and included in displays. You can use the ait.core.evr.EVRDefn.format_message() method for this.

>>> import ait.core.evr
>>> evr = ait.core.evr.getDefaultDict()[3]
>>> evr.message
'The third evr %s'

We’ll need a bytearray() of data to decode:

>>> data = bytearray([0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x67, 0x72, 0x65, 0x61, 0x74, 0x65, 0x73, 0x74, 0x21, 0x00])

We can now decode that data and include it in our message:

>>> evr.format_message(data)
'The third evr is the greatest!'

!EVR

name:

The EVR’s name

code:

The code that specifies this EVR

desc (optional):

A human readable description of what the EVR represents

message (optional):

A human readable description of what the EVR represents. The message attribute can contain printf strings. The ait.core.evr.EVRDefn class provides an interface for unpacking data into it’s message attribute.