HTTP/2 is a major revision of the HTTP network protocol. Using HTTP/2 can accelerate content delivery and reinforce the security of data transmission. In addition, HTTP/2 enables both clients and servers to achieve high concurrency through a single connection. This topic describes what HTTP/2 is, the benefits of HTTP/2, and how to enable HTTP/2.
- If this is the first time you configure an SSL certificate, you must wait until the certificate takes effect before you can enable HTTP/2.
- If you disable the SSL certificate after you enable HTTP/2, HTTP/2 is automatically disabled.
HTTP/2, formerly named HTTP/2.0, is the latest version of HTTP. Compared with HTTP/1.1, HTTP/2 supports more features. For example, multiplexing, header compression, request prioritization, and server push are supported. HTTP/2 provides optimized performance and is compatible with HTTP/1.1 semantics. HTTP/2 is supported by all major browsers such as Google Chrome, Internet Explorer 11, Safari, and Mozilla Firefox.
- Binary encoding: Unlike the newline delimited plaintext HTTP/1.x protocol, all HTTP/2 communication is split into smaller messages and frames, each of which is encoded in binary format. The binary encoding mechanism makes HTTP/2 more extensible. For example, frames are introduced to transmit data and instructions.
- Content security: HTTP/2 ensures higher security because it is based on HTTPS. You can use HTTP/2 to prevent performance degradation that occurs when you use only HTTPS.
- Multiplexing: HTTP/2 enables a client to make multiple parallel requests through one connection and parallel responses can be returned through the same connection. In addition, multiplexing supports stream dependencies. This allows a client to provide further details of prioritized streams to the server by using the same connection. This way, the delivery of important content is prioritized.
- Header compression: Each HTTP message carries a large number of headers that describe the transferred resource and properties. To reduce the overhead and improve performance, HTTP/2 uses HPACK compression. HTTP/2 requires both the client and server to maintain and update an indexed list of header fields. This list is used as a reference to encode previously transmitted values by transferring index values. This improves the transfer efficiency.
- Log on to the Alibaba Cloud CDN console.
- In the left-side navigation pane, click Domain Names.
- On the Domain Names page, find the domain name that you want to manage and click Manage in the Actions column of the domain name.
- In the management pane of the domain name, click HTTPS.
- In the HTTP/2 section, turn on HTTP/2.