CHANGES:

• cohttp-eio: ensure "Host" header is the first header in http client requests (bikallem #939)
• cohttp-eio: add TE header in client. Check TE header is server (bikallem #941)
• cohttp-eio: add User-Agent header to request from Client (bikallem #940)
• cohttp-eio: add Content-Length header to request/response (bikallem #929)
• cohttp-eio: add cohttp-eio client api - Cohttp_eio.Client (bikallem #879)
• http: add requires_content_length function for requests and responses (bikallem #879)
• cohttp-eio: use Eio.Buf_write and improve server API (talex5 #887)
• cohttp-eio: update to Eio 0.3 (talex5 #886)
• cohttp-eio: convert to Eio.Buf_read (talex5 #882)
• cohttp lwt client: Connection cache and explicit pipelining (madroach #853)
• http: add Http.Request.make and simplify Http.Response.make (bikallem mseri #878)
• http: add pretty printer functions (bikallem #880)
• New eio based client and server on top of the http library (bikallem #857)
• New curl based clients (rgrinberg #813)
  • cohttp-curl-lwt for an Lwt backend
  • cohttp-curl-async for an Async backend
• Completely new Parsing layers for servers (anuragsoni #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 #818)
• Introduce http package containing common signatures and structures useful for compatibility with cohttp - and no dependencies (rgrinberg #812)
• async(server): allow reading number of active connections (anuragsoni #809)
• Various internal refactors (rgrinberg, mseri, #802, #812, #820, #800, #799, #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, #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 #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 #847)
• cohttp(cookies): use case-insensitive comparison to check for set-cookies (mseri #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 #811)
  • refactor: deprecate Cohttp_async.Io (rgrinberg #807)
  • fix: move more internals to Private (rgrinberg #806)
  • fix: deprecate transfer encoding field (rgrinberg #805)
  • refactor: deprecate Cohttp_async.Body_raw (rgrinberg #804)
  • fix: deprecate more aliases (rgrinberg #803)
  • refactor: deprecate connection value(rgrinberg #798)
  • refactor: deprecate using attributes (rgrinberg #796)
  • cleanup: remove cohttp-{curl,server}-async (rgrinberg #904)
  • cleanup: remove cohttp-{curl,server,proxy}-lwt (rgrinberg #904)
  • fix: all parsers now follow the spec and require \r\n endings. Previously, the \r was optional. (rgrinberg, #921)
• cohttp-lwt-jsoo: do not instantiate XMLHttpRequest object on boot (mefyl #922)