Export Process instance details

User Story (Required on creation):

Camunda users often operate the engine in an environment consisting of several other engines, backend systems, ... . The ownership of these systems might be in several different teams / several operators. One business transaction is E2E executed on several of these systems. If there is an error, it frequently must be fixed manually / semi-automated.

To ease communication between teams / operators (that e.g. do not use Cockpit), exporting relevant process instance data in a text-based format is a useful feature. 

Functional Requirements (Required before implementation):

• The results of the process instance search on the process dashboard (https://docs.camunda.org/manual/7.16/webapps/cockpit/bpmn/dashboard/#deployed-processes) can be exported
• Format: CSV (needs final clarification)
• Selection:
  • All results of the search
  • The current page
  • A selection of instances on the current page
• Users can choose what properties are included in the result
• The following properties can be included in the result:
  • All historic process instance attributes, especially including
    • Process instance id
    • Business Key
    • Process definition id
    • Start and end date of process instance
  • Process instance variables of the user's choice
  • The currently active activities in the process instance
  • The exception messages of jobs in the process instance (regardless of number of retries left)

Technical Requirements (Required before implementation):

• tbd: Clarify how exporting all results plays together with the pagination limit that users can configure
• tbd: The selection of exported properties can be stored in the local storage of the browser
• tbd: Decide if public API or Cockpit private endpoint
• tbd: Consider having a warning if a user is about to export a very large result set
• tbd: Clarify how 1:N relationships of process instance with secondary entities (active activities, job exception messages) should turn out in the result. Currently known options:
  • Separate multiple values by comma within one CSV attribute (nesting in CSV)
  • Export multiple rows when there is more than one related entity
    • May have the permutation problem. For example if we have two active activities and two job failure messages, do we export 2*2 = 4 rows with all combinations?
  • Use JSON instead of CSV

Limitations of Scope (Optional):

Hints (optional):