Compatibility with YADE 1.x - support for alternative fragments

Description

• Behavior in YADE 1.x
  • YADE 1.x supports the concept of alternative fragments, which can be configured for both Source and Target.
  • This functionality behaves as follows:
    • If the connection to the host defined in the main fragment fails, YADE 1.x automatically attempts to use the alternative fragment for file transfer.
  • Case 1: Alternative Fragment identical to Main Fragment
    • The alternative fragment can reference the same endpoint as the main fragment.
    • In this case, it effectively acts as a retry mechanism for connection errors.
  • Case 2: Alternative Fragment differs from Main Fragment
    • Note: YADE 1.x allows configuration across different fragment types, e.g.: Main: SFTP, Alternative: SMB
    • This introduces several implications:
      • The alternative host must provide an identical folder structure as the main host.
      • The actual Source/Target used is determined at runtime, making behavior non-deterministic.
      • Downstream job processing becomes unpredictable, since the effective Source/Target may change dynamically.
      • YADE 1.x also allows independent Pre-/Post-Processing configurations for alternative fragments, which may differ from the main fragment and further increase complexity and lack of transparency.

• Behavior in YADE 2.x
  • YADE 2.x does not support alternative fragments.
  • Replacement for Case 1 (Retry Scenario)
    • For unstable networks, retry behavior can be configured via:
      • Profile / ... / TransferOptions / RetryOnConnectionError
        • Retry logic is explicitly configurable and deterministic.
  • Replacement for Case 2 (Fallback to Alternative)
    • Fallback logic can be implemented explicitly in the workflow using the Try/Catch instruction.
    • Note:
      • The Catch block is triggered for all transfer errors.
      • However, there is currently no way to distinguish between connection-related and other errors.
      • This is planned to be addressed in upcoming releases.

Maintainer Notes

• The issue is dismissed as architecture changes do not allow offering compatible behavior to YADE 1.x.
• YADE-651 offers the feature from a slightly different design.