Developing a Trigger Condition
This chapter contains the following section:
About Adding New
To create a trigger for a specific
new purpose, you must have a trigger condition that is correctly defined. If an
appropriate trigger condition does not already exist, you have to implement it.
Likewise, if the appropriate and necessary components of the condition are not
yet defined, then you can implement them using the information provided here.
In the Create Trigger Wizard (found under
Specify Conditions step, you should have the
options available to set up the new trigger condition.
A trigger is composed of two components:
MonitoredContextIf is supposed to describe the object
that is to be monitored and supply a list of references to the object. When you
element of the Wizard, you should see
controls and related options that allow you to select the object and the
references to it. For example, the
MonitoredContextIf might be used to monitor the "Dummy
Device" objects and to return a list of all the Dummy Devices available.
MonitoredParamterIf is used in the definition of a
trigger condition as follows:
So, for example, a trigger condition such as "Dummy Device ddTwo
Status is down" can be logically tested as a condition. If the monitored Status
parameter renders the statement True, the trigger condition is met.
It provides the specific
parameter to be examined. For example, it could be a parameter representing the
status of the particular Dummy Device (for example, ddTwo) as defined by the
It supplies the operations
that can be applied to the parameter. Typical operations include, for example:,
(The appropriate operations depend on the implementation.)
It supplies a list of
values, each of which can be logically compared against the parameter to
activate the trigger.
Adding New Trigger
Before You Begin
Refer to the Open
Automation javadocs for details on the implementation of the interface.
|| Implement a
MonitoredContextIf and all the applicable
Refer to the
sample code for an example.
|| Register the
trigger condition into the system.
has a static method for this purpose.
see the following classes:
MonitoredContextIf and its
MonitoredParameterIfs together into a
the monitoring trigger with the utility.