Why HttpClient implementation is limited to use Curl?

[issei-m]

Nowadays, we have a variety of HTTP client implementations in the PHP world, and nothing seems to rely on the specific curl's feature found in HttpCurlInterface, so I suppose that we can simply have just an interface like HttpClientInterface instead of the curl-limited interface.

[bjguillot]

Is the usage of Curl in current SDK causing an issue with your integration? Is it preventing you from using the HTTP client implementation of your choice in the rest of your code?

[issei-m]

Actually, not yet.
But we sometimes need to use a web server that is limited of use where for example we cannot install PHP extension modules like curl anyway.
In such a case, it's more useful if it requires no extension module.
Also, that would match the policy only requiring PHP >=5.5 which came end-of-life in 2016 because on these servers I mentioned above, typically PHP version would possibly be older.

If this proposal would be legit, I'm willing to open a PullReq for it.