Property Reader

Property readers are used to read out a single value / property from a device and normalize it afterwards. Every property reader can consist of the following parameters:

Parameters	Description
pre_condition	Condition has to hold true to be able to read out data
detection	Describes how to retrieve the value
operators	List / array of operators to be used on the value after retrieving it

The pre_condition parameter is optional and consists of conditions. If the parameter is not set, there are no pre-conditions and Thola will try to read out a property with this property reader.

The detection value is mandatory and determines how Thola will retrieve the requested property. Depending on which detection type is used, additonal parameters need to be added to the property reader, so it can read out the property. For example, when reading out a property with an snmpget request, the oid which will be requested needs to be defined.

Currently, there are the following detection types with the following additional parameters:

Detection	Parameters	Description
SysDescription	/	Retrieve value from SysDescription.
SysObjectID	/	Retrieve value from SysObjectID.
snmpget	oid	Retrieve value with snmpget.
constant	value	Use a constant value.

The operators parameter is optional and offers a way to normalize a value after retrieving it from the device. There are several possible operators, which are defined here.

The following example shows a property reader for reading out the model description of a JunOS device:

detection: SysDescription
operators:
  - type: modify
    modify_method: regexSubmatch
    regex: '^Juniper Networks, Inc\.\s([^,^\s^$\n]+( \[[^\]]+\])?)(,|\s|$|\n)'
    format: "$1"
  - type: modify
    modify_method: toUpperCase