---
title: HTTP/2.0
menu: docs_proto
weight: 250
---

`actix-web` automatically upgrades connections to *HTTP/2.0* if possible.

# Negotiation

*HTTP/2.0* protocol over tls without prior knowledge requires
[tls alpn](https://tools.ietf.org/html/rfc7301).

> Currently, only `rust-openssl` has support.

`alpn` negotiation requires enabling the feature. When enabled, `HttpServer` provides the
[bind_ssl](../../actix-web/actix_web/server/struct.HttpServer.html#method.serve_tls) method.

```toml
[dependencies]
actix-web = { version = "{{< actix-version "actix-web" >}}", features = ["ssl"] }
openssl = { version = "0.10", features = ["v110"] }
```
{{< include-example example="http20" file="main.rs" section="main" >}}

Upgrades to *HTTP/2.0* schema described in
[rfc section 3.2](https://http2.github.io/http2-spec/#rfc.section.3.2) is not supported.
Starting *HTTP/2* with prior knowledge is supported for both clear text connection
and tls connection. [rfc section 3.4](https://http2.github.io/http2-spec/#rfc.section.3.4)

> Check out [examples/tls](https://github.com/actix/examples/tree/master/tls)
> for a concrete example.