Change (Variable Changed)

This is a "system-level" counterpart of updated event. The "change" event is fired when value of the some variable defined in this context is modified. In contrast to the "updated" event that is designed to deliver property changes to other system modules, the "change" event is used to persistently store historical property values. The history of this event is internally used by different system components to retrieve property history.

"change" event should be never used for tracking updates of a certain variable, its delivery to listeners is not guaranteed. Use "updated" event instead.

This event is generated on updates of most variables. However, there are certain variables those value is generated on-the-fly, during the read operation. Every read of such a variable may result to a different value, but there are not explicit "update points" for them. Thus, Updated event will not be generated for those variables.

Event Name

change

Permissions:

Accessible at Observer permission level

Expiration Period:

Dynamic, depends on a type of the variable those value was updated.

Records:

1

Record Format:

Field Name

Field Type

Notes

variable

String

Name of changed variable.

value

Data Table

New value of the variable.

data

String

Value of the variable encoded into string, without format. This field is filled only when "value" field is NULL.

Was this page helpful?