[ANN] cohttp 6.0.0~alpha0 released

[mseri]

I’d like to announce the release of the first alpha version of the new cohttp. If you are not familiar with it, cohttp is an OCaml library for creating HTTP clients and servers. It has a portable HTTP parser, and implementations using various asynchronous programming libraries.

This experimental release introduces a number of changes in cohttp’s internals and in the libraries provided. In particular:

• the new http library provides essential type definitions used in cohttp and also includes a new, extremely fast, http parser. The library is designed to have practically no dependencies and make it easy for other packages to easily interoperate with cohttp.
• cohttp-server-lwt-unix is a new lwt server backend that does not rely on conduit and uses direct lwt-io access. This should resolve most of the latency issues encountered with the old cohttp-lwt-unix library.
• cohttp-curl is a new libcurl-based (via ocurl) library, also providing an lwt and an async backend.
• cohttp-eio uses eio to leverage new features from multicore ocaml, it also include new very fast parser to fully benefit from eio at all levels.

All of this comes with a large number of fixed bugs, improved testing, new long-awaited features (like the http cache for cohttp-lwt-unix) and lots of internal refactoring and cleanup.

We would like to thank @rgrinberg @mefyl @anuragsoni @BikalGurung and all the people that contributed with issues, discussions, PRs and design ideas leading to this release.

LINKS

• Project page: GitHub - mirage/ocaml-cohttp: An OCaml library for HTTP clients and servers using Lwt or Async
• Documentation for the alpha version needs to be generated locally with dune build @doc

CHANGES

• cohttp-eio: ensure “Host” header is the first header in http client requests (bikallem cohttp-eio(client): Ensure “Host” header is the first header in requests mirage/ocaml-cohttp#939)
• cohttp-eio: add TE header in client. Check TE header is server (bikallem Add TE header in client. Check TE header in server mirage/ocaml-cohttp#941)
• cohttp-eio: add User-Agent header to request from Client (bikallem cohttp-eio(client): add User-Agent header mirage/ocaml-cohttp#940)
• cohttp-eio: add Content-Length header to request/response (bikallem cohttp-eio: Add Content-Length header to request/response mirage/ocaml-cohttp#929)
• cohttp-eio: add cohttp-eio client api - Cohttp_eio.Client (bikallem cohttp-eio Client module mirage/ocaml-cohttp#879)
• http: add requires_content_length function for requests and responses (bikallem cohttp-eio Client module mirage/ocaml-cohttp#879)
• cohttp-eio: use Eio.Buf_write and improve server API (talex5 cohttp-eio: improve server API mirage/ocaml-cohttp#887)
• cohttp-eio: update to Eio 0.3 (talex5 Update for Eio 0.3 mirage/ocaml-cohttp#886)
• cohttp-eio: convert to Eio.Buf_read (talex5 cohttp-eio: use Eio.Buf_read mirage/ocaml-cohttp#882)
• cohttp lwt client: Connection cache and explicit pipelining (madroach Explicit pipelining and connection cache mirage/ocaml-cohttp#853)
• http: add Http.Request.make and simplify Http.Response.make (bikallem mseri http: add Request.make mirage/ocaml-cohttp#878)
• http: add pretty printer functions (bikallem http: add pretty printer functions mirage/ocaml-cohttp#880)
• New eio based client and server on top of the http library (bikallem RFC: eio-only version of cohttp mirage/ocaml-cohttp#857)
• New curl based clients (rgrinberg feature: Curl Based client mirage/ocaml-cohttp#813)
  • cohttp-curl-lwt for an Lwt backend
  • cohttp-curl-async for an Async backend
• Completely new Parsing layers for servers (anuragsoni Use new request parser mirage/ocaml-cohttp#819)
  • Cohttp now uses an optimized parser for requests.
  • The new parser produces much less temporary buffers during read operations
    in servers.
• Faster header comparison (gasche cohttp.headers: faster faster comparison mirage/ocaml-cohttp#818)
• Introduce http package containing common signatures and structures useful for
  compatibility with cohttp - and no dependencies (rgrinberg feature: introduce http package mirage/ocaml-cohttp#812)
• async(server): allow reading number of active connections (anuragsoni async(server): allow reading number of active connections mirage/ocaml-cohttp#809)
• Various internal refactors (rgrinberg, mseri, fix: fast comparison of request/response mirage/ocaml-cohttp#802, feature: introduce http package mirage/ocaml-cohttp#812, http, cohttp: refactor Header module tests mirage/ocaml-cohttp#820, refactor: remove some Stringext usage mirage/ocaml-cohttp#800, refactor: explicit signature for async mirage/ocaml-cohttp#799,
  refactor: stop relying on name mangling mirage/ocaml-cohttp#797)
• http (all cohttp server backends): Consider the connection header in response
  in addition to the request when deciding on whether to keep a connection
  alive (anuragsoni, http: Consider the user provided response when considering connection keep-alive mirage/ocaml-cohttp#843)
  • The user provided Response can contain a connection header. That header
    will also be considered in addition to the connection header in requests
    when deciding whether to use keep-alive. This allows a handler to decide to
    close a connection even if the client requested a keep-alive in the
    request.
• async(server): allow creating a server without using conduit (anuragsoni Allow creating cohttp-async servers with existing reader/writers mirage/ocaml-cohttp#839)
  • Add Cohttp_async.Server.Expert.create and
    Cohttp_async.Server.Expert.create_with_response_actionthat can be used to
    create a server without going through Conduit. This allows creating an
    async TCP server using the Tcp module from Async_unix and lets the user
    have more control over how the Reader.t and Writer.t are created.
• http(header): faster to_lines and to_frames implementation (mseri bench(http): optimize to_frames and to_lines functions mirage/ocaml-cohttp#847)
• cohttp(cookies): use case-insensitive comparison to check for set-cookies (mseri Cookies: case-insensitive check of set-cookies mirage/ocaml-cohttp#858)
• New lwt based server implementation: cohttp-server-lwt-unix: this new implementation does not depend on conduit and has a simpler and
  more flexible API
• async: Adapt cohttp-curl-async to work with core_unix.

BREAKING CHANGES

• refactor: move opam metadata to dune-project (rgrinberg refactor: move opam metadata to dune-project mirage/ocaml-cohttp#811)
• refactor: deprecate Cohttp_async.Io (rgrinberg refactor: deprecate Cohttp_async.Io mirage/ocaml-cohttp#807)
• fix: move more internals to Private (rgrinberg fix: move more internals to Private mirage/ocaml-cohttp#806)
• fix: deprecate transfer encoding field (rgrinberg fix: deprecate transfer encoding field mirage/ocaml-cohttp#805)
• refactor: deprecate Cohttp_async.Body_raw (rgrinberg refactor: deprecate Cohttp_async.Body_raw mirage/ocaml-cohttp#804)
• fix: deprecate more aliases (rgrinberg fix: deprecate more aliases mirage/ocaml-cohttp#803)
• refactor: deprecate connection value(rgrinberg refactor: deprecate connection value mirage/ocaml-cohttp#798)
• refactor: deprecate using attributes (rgrinberg refactor: deprecate using attributes mirage/ocaml-cohttp#796)
• cleanup: remove cohttp-{curl,server}-async (rgrinberg fix: stop installing binaries mirage/ocaml-cohttp#904)
• cleanup: remove cohttp-{curl,server,proxy}-lwt (rgrinberg fix: stop installing binaries mirage/ocaml-cohttp#904)
• fix: all parsers now follow the spec and require \r\n endings.
  Previously, the \r was optional. (rgrinberg, fix: require \r\n in all parsers mirage/ocaml-cohttp#921)
• cohttp-lwt-jsoo: do not instantiate XMLHttpRequest object on boot (mefyl Do not systematically create a XMLHttpRequest object. mirage/ocaml-cohttp#922)