 A typical use for a PIDS would be at the front end of a web server monitoring the HTTP (or HTTPS) stream.Because it understands the HTTP relative to the web server/system it is trying to protect it can offer greater protection than less in-depth techniques such as filtering by IP address or port number alone, however this greater protection comes at the cost of increased computing on the web server.Where HTTPS is in use then this system would need to reside in the "shim" or interface between where HTTPS is un-encrypted and immediately prior to it entering the Web presentation layer.