| <!-- |
| Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. |
| |
| SPDX-License-Identifier: curl |
| --> |
| |
| # Experimental |
| |
| Some features and functionality in curl and libcurl are considered |
| **EXPERIMENTAL**. |
| |
| Experimental support in curl means: |
| |
| 1. Experimental features are provided to allow users to try them out and |
| provide feedback on functionality and API etc before they ship and get |
| "carved in stone". |
| 2. You must enable the feature when invoking configure as otherwise curl is |
| not built with the feature present. |
| 3. We strongly advise against using this feature in production. |
| 4. **We reserve the right to change behavior** of the feature without sticking |
| to our API/ABI rules as we do for regular features, as long as it is marked |
| experimental. |
| 5. Experimental features are clearly marked so in documentation. Beware. |
| |
| ## Graduation |
| |
| 1. Each experimental feature should have a set of documented requirements of |
| what is needed for that feature to graduate. Graduation means being removed |
| from the list of experiments. |
| 2. An experiment should NOT graduate if it needs test cases to be disabled, |
| unless they are for minor features that are clearly documented as not |
| provided by the experiment and then the disabling should be managed inside |
| each affected test case. |
| |
| ## Experimental features right now |
| |
| ### The Hyper HTTP backend |
| |
| Graduation requirements: |
| |
| - HTTP/1 and HTTP/2 support, including multiplexing |
| |
| (Hyper is marked for deprecation. It cannot graduate.) |
| |
| ### HTTP/3 support (non-ngtcp2 backends) |
| |
| Graduation requirements: |
| |
| - The used libraries should be considered out-of-beta with a reasonable |
| expectation of a stable API going forward. |
| |
| - Using HTTP/3 with the given build should perform without risking busy-loops |
| |
| ### The Rustls backend |
| |
| Graduation requirements: |
| |
| - a reasonable expectation of a stable API going forward. |
| |
| ## ECH |
| |
| Use of the HTTPS resource record and Encrypted Client Hello (ECH) when using |
| DoH |
| |
| Graduation requirements: |
| |
| - ECH support exists in at least one widely used TLS library apart from |
| BoringSSL and wolfSSL. |
| |
| - feedback from users saying that ECH works for their use cases |
| |
| - it has been given time to mature, so no earlier than April 2025 (twelve |
| months after being added here) |
