sequence.puml

@startuml

title Lexorank workflows

actor user
participant api as "REST API"
participant lexorank as "Lexorank Flow"
participant storage as "Relational Storage"

group showing existing rows
  user -> api : show all request
  activate api
    api -> lexorank : ""getRows()""
    activate lexorank
      lexorank -> storage : ""getSnapshot()""
      activate storage

      lexorank <-- storage : snapshot of rows and ranks
      deactivate storage
    api <-- lexorank : rows ordered by rank
    deactivate lexorank
  deactivate api
end

group inserting a new row
  user -> api : insert request
    activate api
    api -> lexorank : ""insertAt()""
    activate lexorank
      lexorank -> storage : ""lockSnapshot()""
      activate storage
      lexorank <-- storage : snapshot of rows and ranks

      loop proposed rank collides
        lexorank ->o storage : ""applyUpdateInCascade()""
      end

      lexorank -> storage : ""insertNewRecord()""
      lexorank <-- storage : new row
      deactivate storage
    api <-- lexorank : new row
    deactivate lexorank
    deactivate api
end

group updating an existing row
  user -> api : update request
    activate api
    api -> lexorank : ""changePosition()""
      lexorank -> storage : ""lockSnapshot()""
      activate storage
      lexorank <-- storage : snapshot of rows and ranks

      loop proposed rank collides
        lexorank ->o storage : ""applyUpdateInCascade()""
      end

      lexorank -> storage : ""changeRankTo()""
      lexorank <-- storage : updated row
      deactivate storage
    api <-- lexorank : updated row
    deactivate api
end

@enduml