Gachou API

This project contains the API definitions of the Gachou project.

External APIs

Gachou exposes a RESTful API to the public. The API is currently described by an OpenAPI 2.0 document.

• rest-api.yml
• HTML-Version on the bootprint-playground

Internal APIs

There are a number of APIs in Gachou

• core-api: This API is used by the express-layer to access core-functions of Gachou. It exposes all actions like getting date, modifying the index etc
• tasks-api: This API is used by the Gachou-core implementation to run long running and resource intensive tasks. It limits the number of tasks being run in parallel and provides a rudimentary api for monitoring them.
• bidder-api: Bidder and auctions are used in several places in order to determine the best plugin to do a job. For example, there may be multiple normalizer plugins, but only one is suitable for videos. The auction gives the file to every plugin and asks for a "bid" (a number of how well this plugin can handle the file) and then gives the file to the plugin with the highest bid.
• model: This file contains the shared model that is used in the communication between core-api and plugins. This model is also used in some API responses.

Implementations for these interfaces are part of the gachou-backend project.

Plugins / Components

The actual work is done by several components with their own API. Each have a default implementation but can be exchanged (not yet, but the goal is to make this possible).

• media-store: This component handles the storage and retrieval of media data (i.e. thumbnails and original media files). It provides functions to upload and download both kinds and to iterate all files.
• metadata-handler: This component handles the extraction and update of metadata within the media files.
• metadata-index: This component manages an index of the metadata as well and provides methods to update and search it.
• normalizer: This component converts a media-file to a normalized format that can store XMP-Tags
• thumbnailer: This component converts a media-file to a thumbnail.

Thumbnail specifications

Thumbnail sizes are specified by a string that is parsed by the gachou-core implementation into an object matching the IParsedScaleSpec-interface The format of this string is

{width}x{height}[-crop]

where

• {width} is the target width
• {height} is the target height
• [-crop] is the optional string -crop. If the string is present, the crop-property will be set to true meaning that the image should be cropped to an exact match of the specified size. Default is to scale the image to fit within a box of the given size.