Implementation Architecture

Workflows and Orders

Workflow configurations are deployed from the JOC Cockpit to a Controller that forwards them to the connected Agents:

  • Agents execute instructions and jobs from a workflow.
  • Agents report back execution results and the job log output by returning events.

Orders are managed by the JOC Cockpit and are submitted to Controllers that forward them to the connected Agents:

  • Agents start workflows based on the order's scheduled start time.
  • User interventions include canceling, suspending and resuming orders. Such operations are sent by the JOC Cockpit to the Controller which then forwards them to connected Agents.

Controller and Agent Implementation Architecture

  • A Controller Cluster provides automated fail-over between Active and Standby Controller instances.
  • Controllers hold a journal for restart capabilities which includes workflow configurations and order state events:
    • The JOC Cockpit History Service subscribes to such events to maintain the History and to forward events to the GUI.
    • Events are released by a Controller and the journal shrinks once the History has been persistently stored in the database.
  • Controllers and Agents store messages in their journal and pass them asynchronously. This mechanism recovers communication in case of outages lasting hours or days.

JOC Cockpit Implementation Architecture

  • JOC Cockpit can be operated in the following modes:
    • single instance,
    • active-passive clustered instances with one active instance and any number of standby instances.
  • Cluster Service
  • Event Bus Service
    • An event bus manages communication between JOC Cockpit services:
      • events are published in a producer/consumer (publish/subscribe) model,
      • events are asynchronous, i.e. a service does not rely on immediate responses,
      • events are not persistent, i.e. they are removed after being consumed or after a timeout,
      • events are considered informational for the user interface that is updated in near real-time.
  • Proxy Service
    • On start-up the Proxy will retrieve a snapshot of the Controller's journal and will subsequently receive any events fired by a Controller.
    • The Proxy implements an event queue that is subscribed to by a number of consumers, for example by Background Services and by the GUI.

Further Resources

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