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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 JOC Cockpit to the Controller that 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 that 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
    • manages a number of Background Services:
      • Monitor Service: checks execution history for events that users should be notified about.
      • Restart Service: reruns pending deployments and performs synchronization with a Controller.
      • Cleanup Service: purges the database, e.g. to limit the size of the history.
      • History Service: retrieves execution results and logs from a Controller instance.
      • Daily Plan Service: creates and submits orders to connected Controllers.
    • guarantees service execution:
      • checks the cluster health status of any connected JOC Cockpit instances,
      • performs a fail-over operation in case that the Active JOC Cockpit instance fails.
  • 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 some timeout,
      • events are considered informational for the user interface that displays current data.
  • 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 can be subscribed to by a number of consumers, e.g. by Background Services and by the GUI.

Further Resources

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