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<h2 id="_a_href_index_html_index_a_8594_a_href_modules_html_modules_a_8594_a_href_modules_handlers_html_handlers_a"><a href="index.html">Index</a> → <a href="modules.html">Modules</a> → <a href="modules_handlers.html">Handlers</a></h2>
<div class="sectionbody">
</div>
<h2 id="_handler_http_reverse_proxy">Handler: HTTP reverse proxy</h2>
<div class="sectionbody">
<div class="paragraph"><p>This handler is one of the most demanded features of Cherokee. It
dispatches in-bound network traffic to a set of servers, and presents
a single interface to the requesters. This is particularly useful to
load balance a cluster of webservers at a much higher network stack
level than that allowed by the
<a href="modules_handlers_mirror.html">generic balancer</a>.</p></div>
<div class="paragraph"><p>All connections coming from the Internet addressed to one of the Web
servers are routed through the proxy, which can either deal with the
request or pass it (with or without modifications) to the other web
servers.</p></div>
<div class="paragraph"><p>The reverse proxy can do several interesting things besides simply
load balancing. It can rewrite headers, and it can try to establish
keep-alive connections with every system interfacing with it. That is,
it doesn’t matter if all the clients requesting contents from our
publicly available Reverse Proxy do not support this feature: the
Keep-Alive connections can still be kept within the local pool,
greatly improving performance.</p></div>
<div class="paragraph"><p>The task of the reverse proxy can be summarized in the following
steps.</p></div>
<div class="ulist"><ul>
<li>
<p>
Phase 1: The proxy receives a request, adds the necessary HTTP
headers and rewrites the existing ones according to the specified
rules. It then dispatches the request to one of the machines in the
pool of specified <tt>information sources</tt>.
</p>
</li>
</ul></div>
<div class="imageblock">
<div class="content">
<img src="media/images/proxy_phase1.png" alt="media/images/proxy_phase1.png" />
</div>
</div>
<div class="ulist"><ul>
<li>
<p>
Phase 2: Once the server that has received the request sends back the
response, the reverse proxy deletes the unnecessary return HTTP
headers and sends the response back to the requesting client.
</p>
</li>
</ul></div>
<div class="imageblock">
<div class="content">
<img src="media/images/proxy_phase2.png" alt="media/images/proxy_phase2.png" />
</div>
</div>
<div class="paragraph"><p>To use the HTTP reverse proxy handler you simply have to specify
several parameters. First define a series of
<a href="config_info_sources.html">information sources</a>. Those will be the
ones handling the requests in the end.</p></div>
<div class="imageblock">
<div class="content">
<img src="media/images/admin_handler_proxy.png" alt="media/images/admin_handler_proxy.png" />
</div>
</div>
<div class="paragraph"><p>Then you will have to specify:</p></div>
<div class="ulist"><ul>
<li>
<p>
Reuse connections: the maximum number of connections per server to be
kept with Keep-alive. If not specified, the default value of 16 will
be taken.
</p>
</li>
<li>
<p>
Header additions: to add specific HTTP headers.
</p>
</li>
<li>
<p>
URL rewriting rules, which are specified using regular expressions
to modify URLs before relaying the requests.
</p>
</li>
<li>
<p>
Hidden returned headers: to eliminate specific HTTP headers.
</p>
</li>
<li>
<p>
Balancer: the type of load balancing strategy to be used.
</p>
</li>
<li>
<p>
Information sources: where you will assign the previously defined
sources, which are all the servers from our set to be used in the
cluster of web servers.
</p>
</li>
</ul></div>
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distrib
>
Mandriva
>
2010.1
>
i586
>
media
>
contrib-updates
>
by-pkgid
>
02e45b2cd6a4a47c88f15dd2f64cf46c
>
files
>
886
