产研那边有通过nginx代理进行长连接的需求,咱们都知道默认nginx只支持短连接的,使用长连接需要单独配置
一、
websocket协议提供创建一种支持在server和client之前双向通信的web应用。作为HTML5的一部分,websock使比它之前可用的方式中提供一个种更加简单的方法。大部分现在的浏览器都支持websock,包括chrome,Firefox,Internet浏览器，Opera，和Safari，和越来越多的服务器应用框架也开始支持websock了。
The WebSocket protocol is different from the HTTP protocol,但是websocket握手是兼容http的，用TTP Upgrade方式更新从HTTP到websock的连接。This allows WebSocket applications to more easily fit into existing infrastructures.例如,websock应用能使用标准的http端口80和443进行通信。
A WebSocket application keeps a long?running connection open between the client and the server, facilitating the development of real?time applications. 这个 HTTP Upgrade 机制通过使用" the Upgrade and Connection headers." 来更新从HTTP到websocket的连接。There are some challenges that a reverse proxy server faces in supporting WebSocket. 一个是websocket是一个中hop-by-hop(逐跳)协议， so when a proxy server intercepts an Upgrade request from a client it needs to send its own Upgrade request to the backend server, including the appropriate headers. 还有，websocket连接是长连接，相反使用http时典型的短连接，即反向代理server需要在它们在空闲的时候需要保持这些连接保持open，而不是关闭它们。
NGINX supports WebSocket by allowing a tunnel to be set up between a client and a backend server. 对于nginx发送upgrade请求从client到后端的server, the Upgrade and Connectionheaders must be set explicitly, as in this example:
location /wsapp/ {
proxy_pass http://wsbackend;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
Once this is done, NGINX deals with this as a WebSocket connection.
二、举个栗子。
参考:https://www.nginx.com/blog/websocket-nginx/