Keepin' Alive
--#--
The response that Yahoo sends back is, simply, a header and an HTML page. If 
there are references to images embeded in the HTML <i>(&lt;img src=clear.gif&gt;)</i>, the 
browser must make another GET request for each one it finds.<br>
<br>
This can be slow. To speed things up, most browsers will send a Connection 
header in their requests, telling the server to keep the line open until the 
browser has finished making all its requests. On this next example, we're 
going to use the HEAD method, so you'll just get the headers:<br>
<br>
<code>
HEAD / HTTP/1.0
Connection: Keep-Alive

</code>
<br>
You'll notice that the connection remains open. You can immediately type 
a new request, and send it back. You can keep this up until you tell the 
server you're through by changing your Connection header to <i>Connection: 
close</i><br>
<br>
If you just send a <i>Connection: close</i> header by itself, you'll likely
get a "400 Bad Request" response from the server. Make a valid request, 
closing the connection as you do so:<br>
<br>
<code>
HTTP/1.1 200 OK
Date: Fri, 01 Oct 1999 00:57:02 GMT
Server: Apache/1.3.6 (Unix)
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Content-Type: text/html

HEAD / HTTP/1.0
Connection: close


HTTP/1.1 200 OK
Date: Fri, 01 Oct 1999 00:57:09 GMT
Server: Apache/1.3.6 (Unix)
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Content-Type: text/html

Connection closed by foreign host.
</code>
<br>
The Keep-Alive connection has become so prevalent and even necessary to the 
way the Web operates now that it is the default connection type in the new 
HTTP/1.1 protocol version. As we will see shortly, the major Web servers 
already use HTTP/1.1 in their responses, and even Microsoft's Internet 
Explorer 4.0 and above browsers use it for non-proxied requests.
<br>