| <!-- | |
| Copyright (C) Daniel Stenberg, <[email protected]>, 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) | |