Rule Engine

Information

Related task: See Manage Rules to create, edit, group, and enable Rules.

This reference defines the Rule Engine terms, logic, trigger families, and action families used by the hi system. A Rule evaluates one or more triggers and performs its configured actions when the trigger expression evaluates positively.

Overview

Rules can support Tally-driven GPO switching, scheduled actions, parameter changes, routing actions, Snapshot recall, and Metadata or Tag updates. Rule Groups allow related Rules to be enabled or disabled together.

Concept

The Rule Engine listens to events from many parts of the hi system and can trigger actions across the system.

Rule Engine Architecture

A Rule consists of one or more trigger definitions and one or more action definitions. Rules are organized into Rule Groups for easier management. Rule Groups can be enabled or disabled as a unit, which is useful for switching between different operational configurations (for example, enabling a "Show" group and disabling a "Rehearsal" group).

Many system events can serve as a trigger: Tally changes, GPI status changes on connected hiContact GPIO boxes, changes of parameters monitored by the system, or a scheduled timestamp. Multiple triggers can be combined in the same Rule with a logical relation between them. Each time a trigger changes, the Rule Engine evaluates the trigger side of the Rule. If the trigger side evaluates positively, the Rule fires and the configured actions are performed.

Actions can influence many parts of the system - for example, changing Tallies, setting GPOs on connected boxes, or changing parameters. Multiple actions can be combined in a single Rule. All actions execute simultaneously once the trigger side evaluates positively and the Rule fires.

Stateful and Event-based Rules

A Rule and its triggers and actions can be either stateful or event-based.

Stateful Rules

A stateful Rule can be active or inactive, and stateful actions can follow this state.

Information

Example: "When the RED Tally is active on 'CCU 1' / 'Camera In', let 'CCU 1 RED TALLY' on GPIO-BOX-1 follow the trigger." The status of the GPO 'CCU 1 RED TALLY' follows the status of the Tally on the specified Port.

Event-based Rules

An event-based Rule fires when something changes. It does not provide an active or inactive state, so it can use only actions that do not require a state.

Combining Stateful and Event-based Triggers and Actions

Combining multiple stateful triggers makes the Rule stateful, so stateful actions are available. Combining stateful and event-based triggers makes the Rule event-based, so only actions that do not require a state are available.

Multi-Trigger Logic (AND/OR Combinations)

When a Rule has multiple triggers, the logical relationship between them is configured using a column-based system:

Each column represents an AND-combination: all triggers set to ON within a column must be active for that column to evaluate as true.
Multiple columns are OR-combined: if any column evaluates as true, the Rule fires.
Within each column, triggers can be set to ON (must be active), OFF (must be inactive), or empty (ignored for this column).

This system allows complex logical expressions. For example, to create the logic "Fire when Button A is pressed AND Source X is connected to Destination Y, OR when Button B is pressed alone," configure two columns: Column 1 with both triggers set to ON, and Column 2 with only Button B set to ON.

Available Triggers

Trigger Type in the Interface	Description	Stateful Variants	Event-Based Variants
on a Connection / Crosspoint	Monitors a defined output Port and fires when a change occurs	When a specific Source is connected to a specific Destination	When the Source of a specific Destination changes
on a GPI Input	Monitors a GPI input Port from a hiContact GPIO box	When a specific GPI is ON (or OFF)	When the status of a specific GPI changes
on a Tally change	Monitors a Tally color in hi	When a Tally on a specific Essence Port goes ON or OFF	When any Tally of a defined color changes
on Button press	Creates a button on the Control Panel and Hardware Panels	A button of "toggle" type (on/off)	A button of "push" type (fire once)
on Parameter change	Monitors a pinned parameter	When the parameter has a specific value or meets a configured state condition	On a change of the parameter's value
on Schedule	Fires on a configured date and time, which can recur hourly, daily, or at another interval	-	When the current time moves past the configured timestamp
on Metadata change	Monitors a Port for a specified metadata key	When metadata has a specific value for a key	On any change of metadata at a specified key
on Preset Change	Monitors Preset activity for selected users or panels	While a configured Preset remains active	When a user enters or leaves a configured Preset

Available Actions

Action Type in the Interface	Description	Variants requiring state	Variants not requiring state
create a Connection / Crosspoint	Connects an input to an output on a routing Node	Create connection when active/inactive toggle between two Sources	Create connection when active follow source of trigger
switch a GPO Output	Closes a configured GPO on a hiContact GPIO box	Let GPO follow the trigger	Set GPO ON Set GPO Off Impulse
change a Tally	Changes Tally status on a specific Essence Port	Let Tally follow the trigger	Set Tally on Set Tally off
activate / deactivate Tally	Changes status of a Tally Source	Let Tally follow the trigger	Enable/disable Tally from Source
change a Parameter	Changes value of a pinned parameter	Set value when active/inactive toggle between values	Set value when active
recall a Snapshot	Recalls a Snapshot	Recall when active/inactive toggle between two	Recall when active
send HTTP Request	Sends an HTTP request to an endpoint	-	send HTTP Request
enable / disable a Rule or a Rule Group	Enables or disables Rules or groups	Enable/disable following trigger	Enable/disable selected Rule/group
change Metadata	Inserts a key/value-pair of Metadata on an Essence Port	Metadata follows trigger	Set Metadata Remove Metadata
control a Video Server	Controls playback on a video server player channel	-	Stop Cue Play Pause
send commands via telnet	Sends a text command to a device using Telnet	-	Send command to host:port with optional CR+LF
assign / unassign Tags To Ports	Updates Tag assignments on Ports based on trigger conditions	Set Tag when active/inactive	Set Tag when active
lock / unlock destination ports	Locks or unlocks selected Destination Ports Port Containers or Portals	Lock follows Trigger	Lock Unlock

For Follow source of trigger if available, see the routing example, GPO Impulse for pulse behavior, and Destination Lock States Reference for lock authority.

Rule Example

Constraints

An on Button press trigger needs at least one Tag before its button appears on the Control Panel or the Hardware Panels. See Creating Rules.
A Rule that combines stateful and event-based triggers is event-based and can use only actions that do not require state.
Trigger and action availability depends on the configured resources, connected devices, and supported integrations.
Creating or changing Rules requires the Rule admin role and the applicable installed license scope.

See Manage Rules for creating, editing, and managing Rules and Rule Groups in the system.
See Tally and Labels for the Tally propagation model used by Tally triggers and actions.