package ezcurl-lwt

EZCurl

A simple wrapper around OCurl, for easy tasks around http.

project goals

• be as simple to use as possible.

• be as reliable as possible (work is done by cURL and the ocurl bindings anyway).

• stable API with few dependencies, so that user code compiles without breakage for a long time.

Installation

• for the synchronous library: opam install ezcurl

• for the lwt-baed library: opam install ezcurl-lwt (depends on ezcurl)

Usage

A small web crawler can be found in examples/argiope. It's very incomplete and naive but demonstrates basic usage of Ezcurl_lwt.get.

Synchronous API

The library lives in a module Ezcurl, which wraps Curl.t with functions such as get that combine many different low level API calls into one. It also follows redirections by default, and returns a Ezcurl.response object that contains the body, headers, and error code.

# #require "ezcurl";;
# let url = "https://curl.haxx.se/";;
val url : string = "https://curl.haxx.se/"
# let res = Ezcurl.get ~url ();;
...
# let content = match res with Ok c -> c | Error (_,s) -> failwith s;;
val content : Ezcurl_core.response =
...

# content.Ezcurl.code;;
- : int = 200

It is also possible to create a client with Ezcurl.make() and re-use it across calls with the optional parameter client.

Lwt API

Using ezcurl-lwt, a module Ezcurl_lwt becomes available, with functions that are similar to the ones in Ezcurl but are non blocking. This makes it easy to run several queries in parallel:

# #require "ezcurl-lwt";;
# let urls = [
  "https://en.wikipedia.org/wiki/CURL";
  "https://en.wikipedia.org/wiki/OCaml";
  "https://curl.haxx.se/";
  ];;
val urls : string list =
  ["https://en.wikipedia.org/wiki/CURL";
   "https://en.wikipedia.org/wiki/OCaml"; "https://curl.haxx.se/"]

# open Lwt.Infix;;
# let codes =
    List.map (fun url -> Ezcurl_lwt.get ~url ()) urls
    |> Lwt_list.map_p
    (fun fut ->
      fut >>= function
      | Ok r -> Lwt.return r.Ezcurl_lwt.code
      | Error e -> Lwt.fail (Failure "oh no"))
  ;;
...
# codes;;
- : int list = [200; 200; 200]