Understanding Conditions

Conditions are auxiliary controls for event/action rule operation: these are condition variables, 'locks' for the defined event/action mappings.

Each condition can only be in one of two states: OFF or ON (0 or 1, false or true, to put it in terms of formal logic). When applied to a rule, the condition serves as an additional clause for the action execution: the action will only be performed if attached condition is ON, and is never performed if condition is OFF - regardless of whether the event has been triggered. The condition state can be manipulated using the Set condition and Unset condition actions (these exist by default for each and every created condition), which, in their turn, can be set off by some other events.

The conditions are available in the Event & Action Configurator: click the Conditions button in the bottom part of the Rules section to load the existing condition list or create a new one.

Add Condition

To add, remove and manage the conditions in the Macula Console, go to the Events & Actions section and choose Conditions from the menu on the left. Conditions can be also added as you go from the Event & Action Configurator.

Click the + New condition button on the upper panel to bring up the condition configuration dialog box. Here you have to:

• enter a comprehensible title for the condition - usually, the best ones are those which express a state, e.g., camera offline, motion present, door opened etc.

• choose the target server - conditions, as non-global events, are local and operate within a single server

• set condition default state, i.e., the state it is in before it is set or unset for the first time; this can be either ON or OFF

• Save State: Save condition state after server restart

When you have finished, click OK to save and close the dialog box; the newly created condition will appear in the item list and will become available in the Event & Action Configurator.

Use the buttons on the upper panel to edit and remove the conditions; the filters on the bottom panel will help you load recently added or recently edited items.

Condition Usage Examples

Consider a system that has three cameras installed: Camera A overlooking area A, Camera B overlooking area B that is just next to area A, and Camera C, which is a supplementary PTZ device and can be turned to view both areas and even more, and overlooks area C by default. If a person walks into area A, he/she will be detected by Camera A's video analytics; if he moves on, he will enter area B and the security guard will see him on Camera B.

Now, imagine that Camera B suddenly goes offline. The security guard is OK with that, until there is someone in area B; he notices some motion in area A and takes control of Camera C, and makes it overlook area B, but the person of interest is long gone by that time, and there is no footage of him being present in area B. So, the task is to automate the process so that Camera 3 serves as a backup while Camera B is offline; the configuration in such a case may look as follows:

• Event 1: VCA, source: Camera A

• Event 2: Video Lost, source: Camera B

• Condition: Camera B Offline, default state: OFF

• Action 1: make Camera C go to preset Area B

• Action 2: Set Condition, target: condition Camera B Offline

Rules:

• Event 2 triggers Action 2 (that switches the state of condition Camera B Offline to ON)

• Event 1 triggers Action 1 upon the condition Camera B Offline

Thus, Action 1 (go to the PTZ preset) is only actually triggered then and then only if Camera B Offline condition state is ON, which is not possible while Camera B is online.

Now, we need this to work both ways, i.e., we want to return Camera C to its home position and reset condition state back to OFF when Camera B comes online again. New configuration elements will be added:

• Event 3: Video Restored, source: Camera B

• Action 3: Unset Condition, target: condition Camera B Offline

• Action 4: make Camera C go to preset Area C

Rules:

• Event 3 triggers Action 3 (that switches condition state to OFF)

• Event 3 triggers Action 4

These new rules ensure that, once Camera B is streaming again, Camera C will go back to its original position, thus terminating it as a backup device; and the condition is OFF, meaning that the triggering of VCA rules in area A will not make Camera C move.

The whole setup in Event & Action Configurator is as follows: