28.6 Simulating HTTP Connections

When writing PHP scripts, it is not necessary to understand every detail of the HTTP protocol. I would be straying to include a treatise here, but you ought to have enough understanding so that you could simulate a connect by using telnet. You may know that Web servers listen on port 80 by default. HTTP is a text-based protocol, so it's not hard to telnet directly to a Web server and type a simple request. HTTP has several commands that should be familiar; GET and POST are used most often. HEAD is a command that returns just the headers for a request. Browsers use this command to test whether they really want to get an entire document.

It is especially helpful to simulate an HTTP connection when your script sends custom headers. Figure 28.3 is an example showing a request I made to an Apache server. The text in bold is what I typed. The remote server returned everything else.

Figure 28.3 Simulating an HTTP connection.

# telnet www.example.com 80
Trying 192.168.178.111...
Connected to www.example.com.
Escape character is '^]'.
HEAD / HTTP/1.0

HTTP/1.1 200 OK
Date: Wed, 26 Feb 2003 23:19:07 GMT
Server: Apache/1.3.26 (Unix) AuthMySQL/2.20 PHP/4.1.2 mod_gzip/1.3.19.1a mod_ssl/2.8.9
 OpenSSL/0.9.6g
X-Powered-By: PHP/4.1.2
Connection: close
Content-Type: text/html

Connection closed by foreign host.
[root@www tmp]#