Extract the logic merge one topic's content into another into a reusable service. That logic is currently implemented twice: Once (fully-featured) in the companion Data Transfer import/export tool, and once (a stripped-down special case) in the core library's ITopicRepository.Rollback() feature.

Tasks

• Build a generic merge service in core
  • ITopicMergeService
  • TopicMergeService
  • MergeStrategy
  • MergeOptions
• Attempt to re-express the existing ITopicRepository.Rollback() merge logic on top of the new merge service (TopicRepository.MergeVersion())
  • Acceptable if this doesn't integrate cleanly; MergeVersion() can stay separate
• Document the ability to seed one repository from another using the merge service (for the Data Transfer Service)
• Upgrade OnTopic-Data-Transfer to depend on the merge service
  • Adopt the shared serialization and merge logic in place of its own types and methods:
    • TopicData
    • RecordData
    • MultiMap
    • Import()
    • Export()
• Create unit tests to validate the above logic