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<html>
<head>
<title>nsvhr</title>
</head>
<body bgcolor="#ffffff">
<h2>nsvhr -- Virtual Hosting Redirector Module</h2>
<pre>$Header: /cvsroot/aolserver/nsvhr/nsvhr.html,v 1.1.1.1 2001/01/31 21:01:56 kriston Exp $
</pre>
<br>
<a href="#Theory_of_Operation">Theory of Operation</a><br>
<a href="#Known_Issues">Known Issues</a><br>
<a href="#Sample_Configuration">Sample Configuration</a><br>
<br>
<br>
<h3><a name="Theory_of_Operation"></a>Theory of Operation</h3>
Despite its name, the nsvhr module is a proxy that connects to remote hosts
depending on the "Host:" header presented by the client. It can connect
to these remote hosts using <a href="../nssock/nssock.html">nssock</a>or <a href="../nsunix/nsunix.html">nsunix</a>.<br>
<br>
<h3><a name="Known_Issues"></a>Known Issues</h3>
On the proxied remote host, commands like [ns_conn location] might be misleading.<br>
<br>
It's not clear whether the "Host:" header is properly rewritten for the remote
host.<br>
<br>
The code that processes the "Host:" header from the client is unsmart.<br>
<br>
Users seem to habitually confuse nsvhr with the old AOLserver 2.x Virtual
Hosting feature. These are completely different concepts that have little
to do with each other. The sole purpose of nsvhr is to <b>proxy </b>connections
to other servers based on the "Host:" header presented by the client. <i>The
nsvhr module is not designed for in-process virtual hosting a la AOLserver
2.x.</i><br>
<br>
<h3><a name="Sample_Configuration"></a>Sample Configuration</h3>
<br>
Proxying via tcp (the default) is very simple to set up. No special<br>
modules need to be loaded (it uses the already-loaded nssock). It is<br>
less efficient than nsunix and but is the preferred method to<br>
communicate with web servers on a different machine.<br>
<br>
Proxying over a unix domain socket requires loading the nsunix.so<br>
module. Proxying this way is more efficient since the file descriptor<br>
of the socket of the incoming connection is passed to nsunix.so in a<br>
message over the unix domain socket. Then the client communicates<br>
directly with the nsunix.so module and this module is no longer<br>
involved. This is the preferred method to proxy to web servers<br>
running on the same machine.
<pre>
#
# Virtual Hosting redirector -- nsvhr
#
ns_section "ns/server/${servername}/module/nsvhr"
ns_param busyurl "url" ;# Redirect here if back-end times out
ns_param errorurl "url" ;# Redirect here on proxy errors
ns_param method "GET" ;# Methods allowed to proxy
ns_param method "POST" ;# Methods allowed to proxy (can have >1)
ns_param timeout 30 ;# Timeout waiting for back-end
# Register hosts to proxy
ns_section "ns/server/${servername}/module/nsvhr/maps"
ns_param "www.tcpsocket.com" "http://127.0.0.0:2000" ;# HTTP proxy
ns_param "www.domainsocket.com" "unix://somehost" ;# Domain socket
</pre>
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