[Harmony-1] Use the event-driven architecture for file uploading instead of synchronous uploading

[justJavaProgrammer]

Current architecture is using ChainedAlbumReleaseUploader that is synchronous and does not provide ability to add new requirements dynamically.

Motivation: Increase architecture scalability and speed of application. Also, this enhancement make possible adding new features without replacing or updating existing ones.

Requirements:

• Events must be pushed to kafka

• A new AlbumReleaseUploader implementation should be written(maybe re-use existing one, it does what needed but also add some events)

• Make some columns in database tables nullable(such cover image url, track urls, duration of track, duration of album) because it will be updated when a event will be occurred

• Event when album is fully uploaded must not contain nullable elements

• Add docs where missing

• Replace the AlbumUploadingFullyFinishedEvent with BasicAlbumInfoUploadedEvent. It will run other tasks instead indicating that album was fully uploaded List of possible events(can be updated, order is not matter)

• BasicAlbumInfoUploadedEvent - entry point event, always invoked first, indicate that the basic info about album has been saved, basic validation of album has been successfully passed, track(s) info has been saved and files(tracks and cover image) has been successfully uploaded to storage.

BasicAlbumInfoUploadedEvent schema

• id, string - identifier of the album that has been saved and validated
• album_name, string - the album name provided by the artist
• total_song_count, integer - number of tracks in this album
• release_date, ReleaseDate - date at which the album has been uploaded, supported values are: DAY, MONTH, YEAR.
• album_type, AlbumType - type of this album based on song count and duration, supported values are: SINGLE, EPISODE, ALBUM
• Artists, ArtistContainer - list of the artists that performed this album
• Tracks, [UploadedTrackContainer] - tracks that has been uploaded, contains URL to file for further processing, info about each track
• cover_image, Image - single image that represent the album cover, it was not processed and this is the same as was provided by the artist. contains URL to image that was uploaded to storage

[justJavaProgrammer]

https://github.com/Project-Sonata/Harmony/pull/17

[justJavaProgrammer]

https://github.com/Project-Sonata/Harmony/pull/20

[justJavaProgrammer]

https://github.com/Project-Sonata/Harmony/issues/21

Track duration in request body is not longer required

[justJavaProgrammer]

https://github.com/Project-Sonata/Harmony/pull/24

Track duration now set after event was received

[justJavaProgrammer]

https://github.com/Project-Sonata/Harmony/issues/25 Made the album uploading request easier