关于nginx与php-cli之间的“通讯”是怎么实现的？

location ~ [^/]\.php(/|$) {
      fastcgi_pass 通讯方式;
      fastcgi_index index.php;
      include fastcgi.conf;
}

通讯方式
#tcp socket 
fastcgi_pass 127.0.0.1:9000;

#unix socket 
fastcgi_pass unix:/dev/shm/php-cgi.sock;

server {
    listen 80;
    server_name proxy (代理) .stu;
    ...
    location / {
    ...
       #后端http服务地址,可以是任何后端语言写的http服务
        proxy_pass http://127.0.0.1:8080; 
    }
}