<document>
  <header>
    <product>resin</product>
    <title>Virtual Hosting</title>
    <description>
<p>A Resin server can serve many virtual hosts, each with
its own servlets and documents.  The configuration is flexible,
allowing dynamic host deployment in a <code>hosts</code> directory
or using explicit &lt;host> tags for additional control and security,
and compatibility with existing Apache sites, enabling easy upgrades
and evaluation for PHP servers to Quercus.</p>
    </description>

  </header>

  <body>
    <localtoc/>

<s1 title="Overview">

<p>Virtual hosts are multiple internet domains served by the same
Resin server.  Because one JVM handles all the domains, its more memory
and processing efficient, as well as sharing IP addresses.  With Resin,
adding virtual hosts can as easy as creating a directory
like <code>/var/resin/hosts/foo.com</code> and setting up the DNS name.
Explicit virtual host is also possible to match existing layouts, like
matching a <code>/var/resin/htdocs</code> configuration when migrating
a PHP mediawiki or wordpress site to use Quercus
for security and performance.</p>

<p>The virtual host will contain one or
more <a href="deploy-ref.xtp">web-apps</a> to serve the host's contents.
Simple sites will use a fixed root webapp, like the Apache-style
<code>/var/resin/htdocs</code>.  More complicated sites can use a
<code>webapps</code>-style directory.</p>

<p>Each virtual host belongs to a
Resin &lt;cluster>, even if the
cluster has only a single server.</p>

<p>For example, a Resin server might manage both the
<code>www.gryffindor.com</code> and <code>www.slytherin.com</code> domains,
storing the content in separate directories (/var/resin/gryffindor and
/var/resin/slytherin), and using a single IP address for both domains.
In this scenario, both www.gryffindor.com and www.slytherin.com are
registered with the standard domain name service registry as having the IP
address <code>192.168.0.13</code>.  When a user types in the url
<code>http://www.gryffindor.com/hello.jsp</code> in their browser,
the browser will send the HTTP request to the IP address
<code>192.168.0.13</code> and send an additional HTTP header for the
gryffindor host, "Host: www.gryffindor.com".  When Resin receives the request
it will grab the host header, and dispatch the request to the configured
virtual host.</p>

<example title="Example: HTTP request headers">
C: GET /test.jsp HTTP/1.1
C: Host: www.gryffindor.com
C:
</example>

<ol>
<li>host name</li>
<li>host aliases</li>
<li>optional host.xml</li>
<li>root directory</li>
<li>web-applications</li>
<li>configuration environment</li>
<li>logging</li>
</ol>

</s1>

<s1 title="Dynamic virtual hosts">

<p>Resin can deploy virtual hosts automatically by scanning a host
deployment directory for virtual host content.  Each sub-directory in
the <code>hosts</code> directory will cause Resin to create a new
virtual host.  To customize the configuration, you can
add a <code>host.xml</code> in the host's root directory for shared
databases, beans or security, or to add
<a href="http-virtual-hosts-ref.xtp#host-alias">&lt;host-alias></a> names.
</p>

<p>You can add hosts dynamically to a running server just by creating
a new host directory.  Resin periodically scans the <code>hosts</code>
directory looking for directory changes.  When it detects a new host directory,
it will automatically start serving files from the new virtual hosts.</p>

<p>If you add a <code>default</code> directory in the <code>hosts</code>,
Resin will use it to serve all unknown virtual hosts.  The default host is
handy for simple servers with only a single virtual host and for sites
where the virtual host is handled in software, like Drupal. If the
<code>default</code> directory is missing, Resin will
return <code>404 Not Found</code> for any unknown virtual hosts.</p>

<example title="Example: virtual host directory structure">
/var/resin/hosts/www.gryffindor.com/
                                 host.xml
                                 log/access.log
                                 webapps/ROOT/index.jsp
                                 webapps/ROOT/WEB-INF/resin-web.xml
				 
/var/resin/hosts/www.slytherin.com/
                                host.xml
                                log/access.log
                                webapps/ROOT/index.php
                                webapps/ROOT/WEB-INF/resin-web.xml
				 
/var/resin/hosts/default/
                      host.xml
                      log/access.log
                      webapps/ROOT/index.php
                      webapps/ROOT/WEB-INF/resin-web.xml

</example>

<s2 title="host-aliasing for dynamic hosts">

<p>Often, the same virtual host will respond to multiple names, like
<code>www.slytherin.com</code> and <code>slytherin.com</code>.  One
name is the primary name and the others are aliases.  In Resin, the
primary name is configured by the <a href="http-virtual-hosts-ref.xtp#host-name">&lt;host-name></a> tag and aliases are configured
by <a href="http-virtual-hosts-ref.xtp#host-alias">&lt;host-alias></a>.  In a dynamic
host configuration, the directory name is used as the <code>host-name</code>
by default, and aliases are declared in the <code>host.xml</code>.</p>

<example title="Example: www.slytherin.com/host.xml">
&lt;host xmlns="http://caucho.com/ns/resin">
  &lt;host-name>www.slytherin.com&lt;/host-name>
  &lt;host-alias>slytherin.com&lt;/host-alias>
  &lt;host-alias>quidditch.slytherin.com&lt;/host-alias>
&lt;/host>
</example>

<p>Since the <code>host.xml</code> is shared for all web-applications in
the host, you can also use it to configure shared resources like security
logins, shared databases, and shared resources.</p>

</s2>

<s2 title="host-deploy configuration">

<p>The <a href="http-virtual-hosts-ref.xtp#host-deploy">&lt;host-deploy></a> tag configures
the dynamic virtual hosting specifying the directory where Resin should
scan for virtual hosts.  Because Resin does not automatically add default
configuration, you will need to also add configuration for the
<code>host.xml</code>, <code>app-default.xml</code> and
<code>web-app-deploy</code>.  Although it's a bit more verbose, the
no-default rule makes Resin more secure and debuggable.  If an item like
a &lt;web-app> is missing, Resin will return <code>404 Not Found</code> for
security.  Because all configuration is explicit, it's ultimately traceable
to the <code>resin.xml</code> which makes debugging more reliable.</p>

<p>Shared host configuration goes in the
<a href="http-virtual-hosts-ref.xtp#host-default">&lt;host-default></a> tag.  In this
case, we've added an optional <code>host.xml</code> for configuration,
an access log in <code>log/access.log</code> and a standard
<code>webapps</code> directory.  The standard servlets and file handling
come from the <code>app-default.xml</code> file.  If you omit either the
app-default.xml or the webapps, you will see <code>404 Not Found</code> for
any requests.</p>

<p>The example below is a complete, working <code>resin.xml</code> listening
to HTTP at port 8080.  The <a href="clustering-overview.xtp">cluster</a>
consists of a single server.  It includes a &lt;<a config-tag="development-mode-error-page"/>&gt; to help debugging
the configuration.  Many sites will omit the error-page to
hide configuration details in case an error occurs on a live site.</p>

<example title="Example: /etc/resin/resin.xml host-deploy configuration">
&lt;resin xmlns="http://caucho.com/ns/resin"
          xmlns:resin="urn:java:com.caucho.resin"&gt;
&lt;cluster id="app-tier">
  &lt;server id="app-a" address="192.168.1.13" port="6800">
    &lt;http port="8080"/>
  &lt;/server>

  &lt;development-mode-error-page/>

  &lt;resin:import path="${__DIR__}/app-default.xml"/>
  
  &lt;host-default&gt;
    &lt;resin:import path="host.xml" optional="true"/>

    &lt;access-log path="log/access.log"/>
	
    &lt;web-app-deploy path="webapps"
           expand-preserve-fileset="WEB-INF/work/**"/>
  &lt;/host-default&gt;

  <b>&lt;host-deploy path="hosts"&gt;
  &lt;/host-deploy&gt;</b>
  
&lt;/cluster&gt;
&lt;/resin&gt;
</example>

<p>Any directory created in <code>${resin.root}/hosts</code> will now
become a virtual
host. You can also place a .jar file in <code>${resin.root}/hosts</code>, it is expanded to
become a virtual host.</p>

<example>
${resin.root}/hosts/www.gryffindor.com/
${resin.root}/hosts/www.gryffindor.com/webapps/ROOT/index.jsp
${resin.root}/hosts/www.gryffindor.com/webapps/foo/index.jsp

${resin.root}/hosts/www.slytherin.com.jar
</example>

<p>Jar libraries and class files that are shared amongst all webapps in the host
can be placed in <code>lib</code> and <code>classes</code> subdirectories of the host:</p>

<example>
${resin.root}/hosts/www.gryffindor.com/lib/mysql-connector-java-3.1.0-alpha-bin.jar 
${resin.root}/hosts/www.gryffindor.com/classes/example/CustomAuthenticator.java
</example>

<p>More information is available in the configuration documentation
for &lt;<a href="http-virtual-hosts-ref.xtp#host-deploy">host-deploy</a>&gt;
and &lt;<a href="http-virtual-hosts-ref.xtp#host-default">host-default</a>&gt;.</p>

</s2>

</s1>

<s1 title="Explicit Virtual Hosting">

<p>In a more structured site, you can take complete control of the
virtual host configuration and configure each virtual host explicitly.
Existing sites wanting to upgrade to Resin or sites with extra security needs
may prefer to configure each &lt;host>  in the resin.xml. For
example, a PHP Drupal site evaluating Quercus to
improve performance and security might use the explicit &lt;host> to
point to the existing <code>/var/resin/htdocs</code> directory.</p>

<p>In the explicit configuration, each virtual host has its
own <a href="http-virtual-hosts-ref.xtp#host">host</a> block.  At the very least, each host
will define the <var>id</var> specifying the host name and a root web-app.
A <a config-tag="root-directory"/> is often used to provide a host specific
root for logfiles.</p>

<p>As with the dynamic hosting, servlets and web-apps must be configured
either in a &lt;host-default> or explicitly.  If they are missing, Resin
will return a <code>404 Not Found</code> for security.  The host id=""
is the default host and will serve any request that doesn't match other
hosts.  If you don't have a default host, Resin will return a
<code>404 Not Found</code> for any unknown host.</p>

<p>The following sample configuration defines an explicit virtual hosts
www.slytherin.com and a default host, each with its own
root directory, access-log and a single explicit
<a href="deploy-ref.xtp">&lt;web-app></a> in the <code>htdocs</code>
directory.  The default virtual host is configured just like a typical
Apache configuration, so it can be used to upgrade an Apache/PHP site
to use Quercus for security and performance.</p>

<example title="Example: /etc/resin/resin.xml">
&lt;resin xmlns="http://caucho.com/ns/resin"
        xmlns:resin="urn:java:com.caucho.resin">
        
&lt;cluster id="app-tier">
  &lt;server id="app-a" address="192.168.1.10" port="6800"&gt;
    &lt;http port="8080"/>
  &lt;/server>

  &lt;development-mode-error-page/>

  &lt;resin:import path="${__DIR__}/app-default.xml"/>

  &lt;host id="">
    &lt;root-directory&gt;/var/resin&lt;/root-directory&gt;

    &lt;access-log path="logs/access.log"/>

    &lt;web-app id="" root-directory="htdocs"/>
  &lt;/host>

  &lt;host id="www.slytherin.com">
    &lt;host-alias>slytherin.com&lt;/host-alias>
    
    &lt;root-directory&gt;/var/slytherin&lt;/root-directory&gt;

    &lt;access-log path="logs/access.log"/>

    &lt;web-app id="" root-directory="htdocs"/>
  &lt;/host>

&lt;/cluster&gt;
&lt;/resin&gt;
</example>

<p>Browsing http://gryffindor.caucho.com/test.php will look for
/var/resin/htdocs/test.php.</p>

<p>Browsing http://slytherin.caucho.com/test.php will look for
/var/slytherin/htdocs/test.php.</p>

</s1>

<s1 title="Server per virtual host">

<p>In some ISP setups, it may make sense to assign a server for each
virtual host.  The isolation of web-apps may not be
sufficient; each host needs a separate JVM.  In this configuration,
each &lt;host> belongs to its own &lt;cluster> and has a dedicated
&lt;server>.  Normally, this configuration will operate using load-balancing,
so the load-balance server will dispatch requests as appropriate.</p>

<p>For further security restrictions, see
the <a href="health-watchdog.xtp">watchdog</a> section.  ISPs can also
use the watchdog to assign different &lt;user-name> values for each
host and can even create chroot directories for each JVM.</p>

<p>A front-end web server receives all requests, and is configured to
dispatch to back-end Resin server that correspond to the host name.</p>

<figure src="config-jvmpervirtualhost.png" width="481" height="145" alt="client <-> front-end webserver <-> (resin:6802(jvm), resin:6803(jvm))"/>

<s2 title="Back-end JVMs">

<p>Each host is placed in its own &lt;cluster> with a dedicated
&lt;server>.  Since the server listens to a TCP port for load-balancing
and clustering messages, each server on the maching needs a different
server port.</p>

<p>In this example, the virtual hosts <code>www.gryffindor.com</code> and
<code>www.slytherin.com</code> each get their own server.  The backend
clusters have their own virtual host.  The frontend load-balancer dispatches
the <a href="clustering-overview.xtp">&lt;resin:LoadBalance></a> tags
to the backend.</p>

<p>This example is split into two blocks to emphasize the frontend and
backend.  Typically, they will both actually be in the same resin.xml
to ensure consistency.</p>

<example title="Example: /etc/resin/resin.xml for backend">
&lt;resin xmlns="http://caucho.com/ns/resin"
          xmlns:resin="urn:java:com.caucho.resin">

  &lt;cluster-default>
    &lt;resin:import path="${resin.home}/conf/app-default.xml"/>
    
    &lt;host-default>
      &lt;web-app-deploy path="webapps"
           expand-preserve-fileset="WEB-INF/work/**"/>
    &lt;/host-default>
  &lt;/cluster-default>

  &lt;cluster id="gryffindor&gt;
    &lt;server id="gryffindor" host="localhost" port="6800"/&gt;

    &lt;host id="www.gryffindor.com"&gt;
  
      &lt;root-directory&gt;/var/resin/gryffindor&lt;/root-directory&gt;

    &lt;/host&gt;
  &lt;/cluster&gt;

  &lt;cluster id="slytherin"&gt;
    &lt;server id="slytherin" host="localhost" port="6801"/&gt;

    &lt;host id="www.slytherin.com"&gt;
  
      &lt;root-directory&gt;/var/resin/slytherin&lt;/root-directory&gt;

    &lt;/host&gt;
  &lt;/cluster&gt;

  &lt;cluster id="web-tier">
    &lt;!-- see below -->
    ...
  &lt;/cluster>

&lt;/resin&gt;
</example>

<p>Each back-end server is started separately:</p>

<example title="Example: starting backend servers">
unix&gt; bin/resin.sh -server gryffindor start
unix&gt; bin/resin.sh -server slytherin start
</example>

<example title="Example: stopping backend servers">
unix&gt; bin/resin.sh -server gryffindor stop
unix&gt; bin/resin.sh -server slytherin stop
</example>
</s2>

<s2 title="Resin web-tier load balancer">

<p>The host-specific back-end servers are ready to receive requests on their server
ports.  A third Resin server can be used as the front-end load-balancer.
It receives all requests and dispatches to the back-end servers.</p>

<figure src="config-jvmpervirtualhost-resin.png" width="481" height="145" alt="client <-> Resin front-end webserver <-> (resin:6802(jvm), resin:6803(jvm))"/>

<p>The Resin web server is configured using <a href="http-rewrite.xtp">rewrite</a> with a <a href="clustering-overview.xtp">&lt;resin:LoadBalance</a> directive to dispatch to the back-end server.  A cluster is
defined for each back-end host, so that the
&lt;load-balance> knows how to find them.</p>

<example title="Example: /etc/resin/resin.xml for front-end web server">
&lt;resin xmlns="http://caucho.com/ns/resin"
     xmlns:resin="urn:java:com.caucho.resin">
     
  &lt;cluster id="web-tier"&gt;
    &lt;server-default>
      &lt;http port="80"/&gt;
    &lt;/server-default>

    &lt;server id="web" address="192.168.2.1" port="6800"/&gt;

    &lt;host id="gryffindor.com"&gt;
      &lt;web-app id="/"&gt;

        &lt;resin:LoadBalance regexp="" cluster="gryffindor"/>

      &lt;/web-app>
    &lt;/host>

    &lt;host id="slytherin.com"&gt;
      &lt;web-app id="/"&gt;

        &lt;resin:LoadBalance regexp="" cluster="slytherin"/>

      &lt;/web-app>
    &lt;/host>
  &lt;/cluster&gt;

  &lt;cluster id="gryffindor"&gt;
    &lt;server id="gryffindor" address="192.168.2.2" port="6800"/>

    &lt;host id="www.gryffindor.com">
      ...
    &lt;/host>
  &lt;/cluster&gt;

  &lt;cluster id="slytherin"&gt;
    &lt;server id="slytherin" address="192.168.2.2" port="6801"/>

    ...
  &lt;/cluster&gt;
&lt;/resin&gt;
</example>

<s3 title="Starting the servers on Unix">

<p>The front-end server JVM is started similar to the back-end JVMs:</p>

<example title="Example: starting the load balancer" >
unix&gt; bin/resin.sh -server web -conf conf/resin.xml start
...
unix&gt; bin/resin.sh -server web -conf conf/resin.xml stop
</example>

</s3> <!-- unix startup -->

<s3 title="Starting the servers on Windows">
<p>With Windows, each JVM is installed as a service. Service is installed using
  setup.exe graphical utility. It's possible to install a number of Resin
  services each using a unique name. The name will need to be supplied into
  'Service Name' field.</p>

<figure src="setup-exe.png" alt="Resin setup.exe screenshot"/>

<p>You will either need to reboot the machine or start the service from the
Control Panel/Services panel to start the server. On a machine reboot, NT will
automatically start the service.</p>

<p>There is a bug in many JDKs which cause the JDK to exit when the
administrator logs out. JDK 1.4 and later can avoid that bug if the JDK is
started with -Xrs.</p>

</s3> <!-- windows startup -->

</s2> <!-- resin frontend -->

</s1> <!-- jvm per virtual host -->

<s1 title="Configuration tasks">

<s2 title="host naming">

<p>The virtual host name can be configured by
an explicit <a href="http-virtual-hosts-ref.xtp#host-name">&lt;host-name></a>, 
a <a href="http-virtual-hosts-ref.xtp#host-alias">&lt;host-alias></a>,
a <a href="http-virtual-hosts-ref.xtp#host-alias-regexp">&lt;host-alias-regexp></a>,
by the <a href="http-virtual-hosts-ref.xtp#host">&lt;host></a> tag or 
implicitly by the <a href="http-virtual-hosts-ref.xtp#host-deploy">&lt;host-deploy></a>.
For explicit configuration styles, the host name and alias
configuration will generally be in the resin.xml.  For dynamic configuration,
the host aliases will typically be in an included <code>host.xml</code> inside
the host directory.</p>

<p>The default host catches all unmatches hosts.  Simpler sites will
use the default host for all requests, while security-conscious sites
may remove the default host entirely.  If the default host is not configured,
Resin will return a <code>404 Not Found</code>.</p>

</s2>

<s2 title="host.xml">

<p>The <code>host.xml</code> is an optional file where virtual hosts can
put host-common configuration.  The <code>host.xml</code>
is a good place for shared resources like authentication, database pools
or host-wide <a href="config-candi.xtp">beans and services</a>.  It's also a
location for the &lt;host-alias> in a dynamic hosting configuration.</p>

<p>The <code>host.xml</code> is configured in a &lt;host-deploy>
or &lt;host-default> by adding a
<a config-tag="resin:import">&lt;resin:import></a> tag
specifying the host.xml name and location.  Because the &lt;host-default>
applies the &lt;resin:import> to every virtual host, it becomes a common
system-wide configuration file.</p>

</s2>

<s2 title="web-applications">

<p>Hosts must define <a href="deploy-ref.xtp">web-apps</a> in order to
serve files, servlets, or PHP pages.  If the host is missing all
webapps, Resin will return <code>404 Not Found</code> for all requests
make to the host.</p>

<p>Both explicit <a href="deploy-ref.xtp#web-app">&lt;web-app></a> and
dynamic <a href="deploy-ref.xtp#web-app-deploy">web-app-deploy</a> tags
are used to configure webapps.  The explicit style is generally used for
Apache-style configuration, while the dynamic style is generally used for
Java app-server .war configuration.</p>

<p>Remember, Resin's default servlets like the file, JSP, and PHP servlets
also need to be defined before they're used.  So all Resin configuration
files need to have a &lt;resin:import> of the <code>conf/app-default.xml</code>
configuration file either in the &lt;cluster> or in a
shared &lt;cluster-default>.  If the app-default.xml is missing, Resin will
not serve static files, JSP, or PHP, and will not even look in the
WEB-INF for resin-web.xml, classes, or lib.</p>

</s2>

</s1>


<s1 title="IP-Based Virtual Hosting">

<p>While Resin's virtual hosting is primarily aimed at named-based
virtual hosts, it's possible to run Resin with IP-Based virtual hosts.</p>

<p>With IP virtual hosting, each &lt;http&gt; block is configured
with the virtual host name.  This configuration will override any
virtual host supplied by the browser.</p>

<example>
&lt;resin xmlns="http://caucho.com/ns/resin">

&lt;cluster id="web-tier">
  &lt;server id="a"&gt;

    &lt;http address="192.168.0.1" port="80"
          virtual-host="slytherin.caucho.com"/&gt;

    &lt;http address="192.168.0.2" port="80"
          virtual-host="gryffindor.caucho.com"/&gt;

  &lt;/server>

  ...

  &lt;host id="slytherin.caucho.com"&gt;
    ...
  &lt;/host&gt;
&lt;/cluster&gt;
&lt;/resin&gt;
</example>

</s1>

<s1 title="Internationalization">

<p>Resin's virtual hosting understands host names encoded using
rfc3490 (Internationalizing Domain Names in Applications).  This support
should be transparent.  Just specify the virtual host as usual, and
Resin will translate the brower's encoded host name
the unicode string.</p>

<p>Support, of course, depends on the browser.  <a href="http://devedge.netscape.com/viewsource/2003/idn/">Mozilla 1.4</a> supports the encoding.

</p></s1>

<s1 title="Virtual Hosts with Apache or IIS">

<p>A common configuration uses virtual hosts with Apache or IIS.
As usual, Apache or IIS will pass matching requests to Resin.</p>

<s2 title="Apache">
<p>The Resin JVM configuration with Apache is identical to the
standalone configuration.  That similarity makes it easy to debug the
Apache configuration by retreating to Resin standalone if needed.</p>

<p>The <var>ServerName</var> directive in Apache with
the <var>UseCanonicalName</var> can be used to 
select a canonical name for the virtual host
virtual hosting work.  When Apache passes the request to Resin, it
tells Resin the <var>ServerName</var>.  Without the <var>ServerName</var>,
Apache will use the "Host:" header in the HTTP request to select which
host to serve.</p>

<example title="httpd.conf">
LoadModule caucho_module /usr/local/apache/libexec/mod_caucho.so

ResinConfigServer localhost 6802

UseCanonicalName on

&lt;VirtualHost 127.0.0.1&gt;
  ServerName gryffindor.caucho.com
&lt;/VirtualHost&gt;

&lt;VirtualHost 192.168.0.1&gt;
  ServerName slytherin.caucho.com
&lt;/VirtualHost&gt;
</example>

<note>You'll the LoadModule must appear before
the ResinConfigServer for Apache to properly understand the
ResinConfigServer command.  If they're missing, Apache will send
an error.</note>
</s2>


<s2 title="Apache front-end">

<p>The host-specific back-end JVMs are ready to receive requests on their server
ports.  Apache is the front-end server, and is configured to dispatch to the
appropriate back-end Resin JVM for the host: </p>

<figure src="config-jvmpervirtualhost-apache.png" width="481" height="145" alt="client <-> Apache <-> (resin:6802(jvm), resin:6803(jvm))"/>

<example title="httpd.conf">
UseCanonicalName on

&lt;VirtualHost 127.0.0.1&gt;
  ServerName gryffindor.caucho.com
  ResinConfigServer 192.168.0.10 6800
&lt;/VirtualHost&gt;

&lt;VirtualHost 192.168.0.1&gt;
  ServerName slytherin.caucho.com
  ResinConfigServer 192.168.0.11 6800
&lt;/VirtualHost&gt;
</example>

<p>When you restart the Apache web server, you can look at
<var>http://gryffindor/caucho-status</var>
and <var>http://slytherin/caucho-status</var> to check
your configuration.  Check that each virtual host is using the
server <var>address</var> and <var>port</var> that you expect.</p>
</s2>

<!--
<s2 title="IIS">
<p>Configuration and installation for IIS virtual sites is discussed in the <a href="../install/install-3rd-party.xtp">IIS installation</a> section.</p>
</s2>
-->
</s1> <!-- with Apache or IIS -->

<s1 title="Testing virtual hosts">
<p>During development and testing, it is often inconvenient or impossible to
use real virtual host names that are registered as internet sites, and resolve
to an internet-available IP address.    OS-level features on the test client
machine can be used to map a virtual host name to an IP address.  

</p><p>For example, developers often run the Resin server and the test client
(usually a browser) on the same machine.  The OS is configured to map the "www.gryffindor.com" and
"www.slytherin.com" names to "127.0.0.1", pointing these host names back to
computer that the client is running on.</p>

<p>Unix users edit the file <code>/etc/hosts</code>:</p>

<example title="/etc/hosts">
127.0.0.1       localhost

127.0.0.1       www.gryffindor.com
127.0.0.1       www.slytherin.com
</example>
<p>Windows user edit the file <code>C:\WINDOWS\SYSTEM32\DRIVERS\ETC\HOSTS</code>:</p>

<example title="C:\WINDOWS\SYSTEM32\DRIVERS\ETC\HOSTS">
127.0.0.1       localhost

127.0.0.1       www.gryffindor.com
127.0.0.1       www.slytherin.com
</example>

</s1>

<s1 title="Deployment">

<s2 title="Overriding web-app-deploy configuration">

<p>The web-app-deploy can override configuration for an expanded war with
a matching &lt;web-app&gt; inside the &lt;web-app-deploy&gt;.  The
&lt;document-directory&gt; is used to match web-apps.</p>

<example title="Example: resin.xml overriding web.xml">
&lt;resin xmlns="http://caucho.com/ns/resin">
&lt;cluster id="">
&lt;host id="">

&lt;web-app-deploy path="webapps"&gt;
  &lt;web-app context-path="/wiki"
              document-directory="wiki"&gt;
    &lt;context-param database="jdbc/wiki"&gt;
  &lt;/web-app&gt;
&lt;/web-app-deploy&gt;

&lt;/host>
&lt;/cluster>
&lt;/resin>
</example>

</s2>

<s2 title="versioning">

<p>The versioning attribute of the &lt;web-app-deploy> tag improves web-app
version updates by enabling a graceful update of sessions.  The web-apps
are named with numeric suffixes, e.g. foo-10, foo-11, etc, and can be
browsed as /foo.  When a new version of the web-app is deployed, Resin
continues to send current session requests to the previous web-app.  New
sessions go to the new web-app version.  So users will not be aware of
the application upgrade.</p>

</s2>

</s1>

</body>
</document>
