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SO Monitoring Feature Requirements

• A design idea
  • Why not Camunda Cockpit as is: current Camunda Cockpit was designed from a BPMN process management perspective (note: need to study for TOSCA cases).
    • It does not meet service-level orchestration monitoring.
    • It is designed for BPMN definition/execution monitoring; require process knowledge for monitoring.
• We need higher-level monitoring abstraction for both BPMN and TOSCA.
  • Associate Service Instance Id (or other keys) to the top-level process instance id. For the association, 
    • Could use a process variable holding the Service Instance id (or other keys), or
    • Could use a database holding the association
  • Allow VID, UUI or external apps monitor process workflow process (graphically and text-based) based on extensible search keys.
• We need a platform level runtime and history process activity report capabilties out of the box.
  • Regardless use of Camunda Enterprise Edition or Community Edition.
  • Query to Camunda/ARIA database to extract activities. 
• The following diagram depicts the high-level concept. 

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SO Scalability Requirements

• SO scalability will be supported by managing multiple SO instances by utilizing OOM.
  • In OOM, the number of SO component instances will be configured to control the number of active SO instances. 
    • Target scalability will be supported. The MariaDB instance number could be different from the rest of SO components.
  • Each BPMN execution engine will be configured for a shared database, so the engine can be scaled promptly and ready to handle assignments.
• SO endpoints will be registered to MSB for communication load-balancing.
• SO run-time scalability handling
  • SO will have multiple Camunda Execution engine instances which share the centralized data store.
    • The centralized data store will be replicated, and the replication will be transparent to other SO components.
  • The individual execution engine instances do not maintain session state across transactions.
    • The complete state is flushed out to the shared database when a process instance is complete or waiting for events (e.g., asynchronous event, message, human task, etc.).
    • Or, asynchronous continuations can be used during the workflow design when it is necessary to control save points actively (by design) and flush out the process instance states to the database.
    • Once a process instance is passivated, another engine instance can pick up and execute the remaining process instance flows.
  • Multiple SDC distribution client instances will be instantiated.
    • A SDC notification will be routed to (or picked up by) one of the SDC notification client instances. Then, the assigned client instance will:
      • query for templates/models from SDC.
      • parse the template/models and store in the Catalog DB.
    • Due to less frequent templates/models changes and SDC notification client activities, a small number (2) of SDC distribution client instances can be configured.
  • Multiple API handler instances will be instantiated, and all of the instances are active (active-active).
    • The requests from VID, External API and UUI towards the API handler instances will be distributed/routed via load-balancing. MSB is expected to handle their load-balancing.
    • An assigned API handler instance will communicate with the orchestration execution engine and Data store in a scalable manner.
      • Communications (invoking BPMN execution) with the orchestration execution engine will be done through MSB, no direct connection with hard-coded endpoints.
      • For storing requests and select recipes, the API Handler will communicate with the Data store (Request DB, Service Catalog), which is replicated.
  • Multiple Resource/Controller Adapters will be instantiated for active-active operations.
    • The communications between the BPMN/TOSCA resource recipes and the adapter instances will be load-balanced through MSB.
  • External communications with other ONAP components such as DACE, OOF, A&AI, SDNC, etc. will be done through MSB/DMaaP in a scalable manner like the above communication requirements. 

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