Assets
This algebra provides vocabulary to define endpoints serving static assets.
The module enriches the Endpoints algebra with new constructors for endpoints and path segments. It also introduces the concepts of AssetRequest, AssetResponse and AssetPath. The typical usage looks like the following:
sourceval assets: Endpoint[AssetRequest, AssetResponse] =
assetsEndpoint(path / "assets" / assetSegments())
The assetsSegments method defines a path containing (possibly) multiple segments.
The concrete instantiation of the AssetRequest and AssetResponse types is left to interpreters. Typically, AssetResponse is mapped to binary data. Interpreters also have to provide a constructor for AssetRequest, so that the endpoint can be called. Typically, such constructors take the path of the asset as a String parameter.
Server interpreters are encouraged to leverage caching HTTP headers such as ETag or Cache-Control, and gzip content encoding. Incidentally, the algebra provides an abstract digest: Map[String, String] member to be overridden by users with digests uniquely identifying the assets:
sourceval digests = Map("main.css" -> "2018-10-09T14:32:12Z")
The content of the digests can be included to the asset segments so that servers know that the requested version of the asset matches the one it uses, enabling servers to indefinitely cache the asset.