For example, the HTTP header Proxy may be converted to "HTTP_PROXY" and some application servers may interpret it as the environment variable HTTP_PROXY (I seem to remember HHVM did it). Good servers have measures in place to handle that header, but it can bite you if you are implementing a new server.
Comments
Yes, just as CGI.
For example, the HTTP header Proxy may be converted to "HTTP_PROXY" and some application servers may interpret it as the environment variable HTTP_PROXY (I seem to remember HHVM did it). Good servers have measures in place to handle that header, but it can bite you if you are implementing a new server.