Code samples of advanced features of Http4s in combination with some features of Fs2 not often seen.
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Code samples of advanced features of Http4s in combination with some features of Fs2 not often seen.

Streaming end to end

  • Server: Streaming responses end to end, from the FileService reading all the directories in your $HOME directory to the FileHttpEndpoint.
  • StreamClient: Parsing chunks of the response body produced by the server in a streaming fashion way.

You'll need two sbt sessions. Run the server in one and after the client in the other to try it out.

Middleware Composition

  • GZip: For compressed responses. Client must set the Accept Encoding header to gzip.
  • AutoSlash: To make endpoints work with and without the slash / at the end.

Response compression is verified by HexNameHttpEndpointSpec. You can also try it out on Postman or similar.

  • Timeout: Handling response timeouts with the given middleware.

The TimeoutHttpEndpoint generates a response in a random time to demonstrate the use.

  • NonStreamResponse: Using the ChunkAggregator middleware to wrap the streaming FileHttpEndpoint and remove the Chunked Transfer Encoding.

The endpoint /v1/nonstream/dirs?depth=3 demonstrates the use case.

Media Type negotiation

  • XML and Json: Decoding request body with either of these types for the same endpoint.

The JsonXmlHttpEndpoint demonstrates this use case and it's validated in its spec.

Multipart Form Data

  • Server: The MultipartHttpEndpoint is responsible for parsing multipart data with the given multipart decoder.
  • MultipartClient: Example uploading both text and an image.

Similar to the streaming example, you'll need to run both Server and MultipartClient to see how it works.

NOTE: Beware of the creation of rick.jpg file in your HOME directory!


  • Basic Auth: Using the given middleware as demonstrated by the BasicAuthHttpEndpoint.
  • OAuth 2: Using GitHub as demonstrated by the GitHubHttpEndpoint.

fs2 examples

In the fs2 package you'll find some practical examples of the few things it's possible to build with this powerful streaming library. This might serve as a starting point, your creativity will do the rest.

fs2.async package

Apart from the use of the three core types Stream[F, O], Pipe[F, I, O] and Sink[F, I] you'll find examples of use of the following types:

  • Topic[F, A]
  • Signal[F, A]
  • Queue[F, A]
  • Ref[F, A]
  • Promise[F, A]
  • Semaphore[F]

In addition to the use of some other functions useful in Parallel and Concurrent scenarios.