Elektra: Use Case: Download configuration snippet in specific format

Elektra 0.8.24

Use Case: Download configuration snippet in specific format

## Summary

- Title: Download configuration snippet in specific format
- Scope: Entry Details
- Level: User Goal
- Actors: Anonymous user (+ all others)
- Brief: Any user can download the configuration snippets in various formats (XML, JSON, ini, ...).

## Scenarios

- Precondition: Entry has been found through search or detailed view of an entry is opened
- Main success scenario: User successfully downloads the raw configuration snippet in the selected format. The snippet can then be stored directly as configuration file.
- Alternative scenario: The specified entry (URI) cannot be found. The user is informed about the error by an error message.
- Error scenario: Technical problems prevent the operation from completing. The user is informed about the error by an error message containing further information.
- Postcondition: The database remains unchanged.
- Non-functional Constraints:
  - Essential functionality of the program