Engine Nodes

The Engine Node data element keeps the state of a separate node. A node is defined as an instance that is deployed on its own environment (read JVM). Engine nodes are created automatically.

Field	Description
name	An auto-generated name based on the getName() method of the java.lang.management.RuntimeMXBean class.
status	Either Active or Not responding.
hostname	The name of the host on which the node is deployed.
master	This is true if and only if the current node is the master node. Only one master node can exist at a time.
lastActive	Actively updated by the node itself. Used to see if the node is still active.
activeSince	When the node was started.

Engine Node Services

Each Engine node will regularly check for Engine Services for which it has no Engine Service Node. If one is found and the Engine Service has not reached its maximum number of nodes, the node will start a timer to start processing this Engine Service.

Field	Description
name	An auto-generated name based of the corresponding Engine Service.
status	The current status of the Engine Node Service.
engineNode	Link to its parent engine node.
engineService	Link to the corresponding Engine Service.
lastRunAt	Updated each time the workflow is processed.
nextRun	An estimate for the next timer tick.

Exceeding the maximum

If at some time the maximum number of nodes has been exceeded (e.g. when the admin has reduced the number of nodes), the Engine Node will try to stop and remove Engine Node Services in order to match the new maximum.

Status values

Status	Description
Not running	If the linked EngineService has status stop.
Not responding	If the linked EngineNode has not been active recently.
Waiting	If the engine is waiting for the next timer tick.
Working	If the engine is currently processing the workflow.
Shutting down / Ready for shutdown	Used when a shutdown signal has occurred. Used to close all running tasks before shutting down.