<document>
<header>
  <title>cluster: Cluster tag configuration</title>
  <version>Resin 3.1</version>

  <description>

  <p>Each &lt;cluster> contains a set of <a href="virtual-host.xtp">virtual
hosts</a> served by a collection of &lt;<a href="server-tags.xtp">server</a>&gt;s.  The cluster provides
<a href="resin-load-balance.xtp">load-balancing</a>
and <a href="config-sessions.xtp">distributed sessions</a> for scalability
and reliability.</p>

  </description>
</header>
<body>

<localtoc/>

<s1 title="See Also">

<ul>
<li>See the <a href="index-tags.xtp">index</a> for a list of all the tags.</li>
<li>See <a href="webapp-tags.xtp">Web Application</a> configuration for web.xml (Servlet) configuration.</li>
<li>See <a href="server-tags.xtp">Server tags</a> for ports, threads, and JVM configuration.</li>
<li>See <a href="config-env.xtp">Resource</a> configuration for resources: classloader, databases, connectors, and resources.</li>
<li>See <a href="config-log.xtp">Log</a> configuration for access log configuration, java.util.logging, and stdout/stderr logging.</li>
</ul>

</s1>

<defun title="&lt;access-log>">

<p>&lt;access-log> configures a HTTP access log for all virtual hosts
in the cluster.
See <a href="host-tags.xtp#%3caccess-log%3d">access-log</a>
in the &lt;host> tag for more information.</p>

</defun>

<defun title="&lt;cache>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;cache> configures the proxy cache (requires Resin Professional).  The
proxy cache improves performance by caching the output of servlets,
jsp and php pages.  For database-heavy pages, this caching can improve
performance and reduce database load by several orders of magnitude.</p>

<p>The proxy cache uses a combination of a memory cache and a disk-based
cache to save large amounts of data with little overhead.</p>

<p>Management of the proxy cache uses the
<a href="javadoc|com.caucho.management.server.ProxyCacheMXBean">ProxyCacheMXBean</a>.</p>

<deftable title="&lt;cache> Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr><td>path</td>
    <td>Path to the persistent cache files.</td>
    <td>cache/</td></tr>
<tr><td>disk-size</td>
    <td>Maximum size of the cache saved on disk.</td>
    <td>1024M</td></tr>
<tr><td>enable</td>
    <td>Enables the proxy cache.</td>
    <td>true</td></tr>
<tr><td>enable-range</td>
    <td>Enables support for the HTTP Range header.</td>
    <td>true</td></tr>
<tr><td>entries</td>
    <td>Maximum number of pages stored in the cache.</td>
    <td>8192</td></tr>
<tr><td>max-entry-size</td>
    <td>Largest page size allowed in the cache.</td>
    <td>1M</td></tr>
<tr><td>memory-size</td>
    <td>Maximum heap memory used to cache blocks.</td>
    <td>8M</td></tr>
<tr><td>rewrite-vary-as-private</td>
    <td>Rewrite Vary headers as Cache-Control: private to avoid browser
and proxy-cache bugs (particularly IE).</td>
    <td>false</td></tr>
</deftable>

<def title="&lt;cache> schema">
element cache {
  disk-size?
  &amp; enable?
  &amp; enable-range?
  &amp; entries?
  &amp; path?
  &amp; max-entry-size?
  &amp; memory-size?
  &amp; rewrite-vary-as-private?
}
</def>

<example title="Example: enabling proxy cache">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;cache entries="16384" disk-size="2G" memory-size="256M"/&gt;

        &lt;server id="a" address="192.168.0.10"/&gt;

        &lt;host host-name="www.foo.com"&gt;
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;cluster>" version="Resin 3.1">
<parents>resin</parents>

<p>&lt;cluster> configures a set of identically-configured servers.
The cluster typically configures a set of &lt;server&gt;s, each with some
ports, and a set of virtual &lt;host&gt;s.</p>

<p>Only one &lt;cluster&gt; is active in any on server.  At runtime,
the &lt;cluster&gt; is selected by the &lt;server&gt; with <var>id</var>
matching the -server-id on the command line.</p>

<deftable title="&lt;cluster> Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>id</td>
  <td>The cluster identifier.</td>
  <td>required</td>
</tr>
<tr>
  <td><a href="host-tags.xtp#access-log">access-log</a></td>
  <td>An access-log shared for all virtual hosts.</td>
  <td></td>
</tr>
<tr>
  <td><a href="#cache">cache</a></td>
  <td>Proxy cache for HTTP-cacheable results.</td>
  <td></td>
</tr>
<tr>
  <td><a href="#connection-error-page">connection-error-page</a></td>
  <td>IIS error page to use when isapi_srun to Resin connection fails</td>
  <td></td>
</tr>
<tr>
  <td><a href="host-tags.xtp#ear-default">ear-default</a></td>
  <td>default values for deployed ear files</td>
  <td></td>
</tr>
<tr>
  <td><a href="#error-page">error-page</a></td>
  <td>Custom error-page when virtual-hosts fail to match</td>
  <td></td>
</tr>
<tr>
  <td>host</td>
  <td>Configures a virtual host</td>
  <td></td>
</tr>
<tr>
  <td>host-default</td>
  <td>Configures defaults to apply to all virtual hosts</td>
  <td></td>
</tr>
<tr>
  <td>host-deploy</td>
  <td>Automatic host deployment based on a deployment directory</td>
  <td></td>
</tr>
<tr>
  <td>ignore-client-disconnect</td>
  <td>Ignores socket exceptions thrown because browser clients have prematurely disconnected</td>
  <td>false</td>
</tr>
<tr>
  <td>invocation-cache-size</td>
  <td>Size of the system-wide URL to servlet invocation mapping cache</td>
  <td>16384</td>
</tr>
<tr>
  <td>invocation-cache-max-url-length</td>
  <td>Maximum URL length saved in the invocation cache</td>
  <td>256</td>
</tr>
<tr>
  <td>machine</td>
  <td>Configuration for grouping &lt;server> onto physical machines</td>
  <td></td>
</tr>
<tr>
  <td>persistent-store</td>
  <td>Configures the distributed/persistent store</td>
  <td></td>
</tr>
<tr>
  <td>ping</td>
  <td>Periodic checking of server URLs to verify server activity</td>
  <td></td>
</tr>
<tr>
  <td>redeploy-mode</td>
  <td>"automatic" or "manual"</td>
  <td>automatic</td>
</tr>
<tr>
  <td><a href="env-tags.xtp#resin:choose">resin:choose</a></td>
  <td>Conditional configuration based on EL expressions</td>
  <td></td>
</tr>
<tr>
  <td><a href="env-tags.xtp#resin:import">resin:import</a></td>
  <td>Imports a custom cluster.xml files for a configuration management </td>
  <td></td>
</tr>
<tr>
  <td><a href="env-tags.xtp#resin:if">resin:if</a></td>
  <td>Conditional configuration based on EL expressions</td>
  <td></td>
</tr>
<tr>
  <td>rewrite-dispatch</td>
  <td>rewrites and dispatches URLs using regular expressions, similar to mod_rewrite</td>
  <td></td>
</tr>
<tr>
  <td>root-directory</td>
  <td>The root filesystem directory for the cluster</td>
  <td>${resin.root}</td>
</tr>
<tr>
  <td><a href="server.xtp">server</a></td>
  <td>Configures JVM instances (servers).  Each cluster needs at least one server</td>
  <td></td>
</tr>
<tr>
  <td>server-default</td>
  <td>Configures defaults for all server instances</td>
  <td></td>
</tr>
<tr>
  <td>server-header</td>
  <td>Configures the HTTP "Server: Resin/xxx" header</td>
  <td>Resin/Version</td>
</tr>
<tr>
  <td>session-cookie</td>
  <td>Configures the servlet cookie name</td>
  <td>JSESSIONID</td>
</tr>
<tr>
  <td>session-sticky-disable</td>
  <td>Disables sticky-sessions on the load balancer</td>
  <td>false</td>
</tr>
<tr>
  <td>url-character-encoding</td>
  <td>Configures the character encoding for URLs</td>
  <td>utf-8</td>
</tr>
<tr>
  <td>url-length-max</td>
  <td>Configures the maximum length of an allowed URL</td>
  <td>8192</td>
</tr>
<tr>
  <td>web-app-default</td>
  <td>Configures defaults to apply to all web-apps in the cluster</td>
  <td></td>
</tr>
</deftable>

<def title="&lt;cluster> schema">
element cluster {
  attribute id { string }
  &amp; <a href="env-tags.xtp">environment resources</a>
  &amp; access-log?
  &amp; cache?
  &amp; connection-error-page?
  &amp; ear-default*
  &amp; error-page*
  &amp; host*
  &amp; host-default*
  &amp; host-deploy*
  &amp; ignore-client-disconnect?
  &amp; invocation-cache-size?
  &amp; invocation-cache-max-url-length?
  &amp; machine*
  &amp; persistent-store?
  &amp; ping*
  &amp; redeploy-mode?
  &amp; resin:choose*
  &amp; resin:import*
  &amp; resin:if*
  &amp; rewrite-dispatch?
  &amp; root-directory?
  &amp; server*
  &amp; server-default*
  &amp; server-header?
  &amp; session-cookie?
  &amp; session-sticky-disable?
  &amp; url-character-encoding?
  &amp; url-length-max?
  &amp; web-app-default*
}
</def>

<example title="Example: cluster-default">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;server-default&gt;
            &lt;http port="8080"/&gt;
        &lt;/server-default&gt;

        &lt;server id="a" address="192.168.0.10"/&gt;
        &lt;server id="b" address="192.168.0.11"/&gt;

        &lt;host host-name="www.foo.com"&gt;
          ...
        &lt;/host&gt;
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

<s2 title="rewrite-vary-as-private">

<p>Because not all browsers understand the Vary header, Resin can rewrite
Vary to a Cache-Control: private.  This rewriting will cache the page
with the Vary in Resin's proxy cache, and also cache the page in the browser.
Any other proxy caches, however, will not be able to cache the page.</p>

<p>The underlying issue is a limitation of browsers such as IE.  When IE
sees a Vary header it doesn't understand, it marks the page as uncacheable.
Since IE only understands "Vary: User-Agent", this would mean IE would
refuse to cache gzipped pages or "Vary: Cookie" pages.</p>

<p>With the &lt;rewrite-vary-as-private> tag, IE will cache the page
since it's rewritten as "Cache-Control: private" with no Vary at all.
Resin will continue to cache the page as normal.</p>

</s2>

</defun>

<defun title="&lt;cluster-default>" version="Resin 3.1">
<parents>resin</parents>

<p>&lt;cluster-default> defines default cluster configuration for all clusters in the &lt;resin&gt; server.</p>

<example title="Example: cluster-default">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster-default&gt;
        &lt;cache entries="16384" memory-size="64M"/&gt;
    &lt;/cluster-default&gt;

    &lt;cluster id="web-tier"&gt;
        ...
    &lt;/cluster&gt;

    &lt;cluster id="app-tier"&gt;
        ...
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;connection-error-page>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;connection-error-page> specifies an error page to be used
by IIS when it can't contact an app-tier Resin.  This directive
only applies to IIS.</p>

<def title="connection-error-page">
element connection-error-page {
  string
}
</def>

</defun>

<defun title="&lt;ear-default>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;ear-default> configures defaults for .ear resource,
i.e. enterprise applications.</p>

</defun>

<defun title="&lt;error-page>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;error-page> defines a web page to be displayed when an error occurs
outside of a virtual host or web-app.
Note, this is not a default error-page, i.e. if
an error occurs inside a &lt;host&gt; or &lt;web-app&gt;, the error-page for
that host or web-app will be used instead.</p>

<p>See <a href="webapp.xtp#error-page">webapp: error-page</a>.</p>

<def title="&lt;error-page> schema">
element error-page {
  (error-code | exception-type)?
  &amp; location?
}
</def>

</defun>

<defun title="&lt;host>" version="Resin 3.0">
<parents>cluster</parents>

<p>&lt;host> configures a virtual host.  Virtual hosts must be
configured explicitly.</p>

<ul>
<li>See <a href="host-tags.xtp">host tags</a> for configuration details.</li>
</ul>

<deftable-childtags title="&lt;host> attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr><td>id</td>
    <td>primary host name</td>
    <td>none</td></tr>
<tr><td>regexp</td>
    <td>Regular expression based host matching</td>
    <td>none</td></tr>
<tr><td>host-name</td>
    <td>Canonical host name</td>
    <td>none</td></tr>
<tr><td>host-alias</td>
    <td>Aliases matching the same host</td>
    <td>none</td></tr>
<tr><td>secure-host-name</td>
    <td>Host to use for a redirect to SSL</td>
    <td>none</td></tr>
<tr><td>root-directory</td>
    <td>Root directory for host files</td>
    <td>parent directory</td></tr>
<tr><td>startup-mode</td>
    <td>'automatic', 'lazy', or 'manual', see <a href="resin-tags.xtp#startup-mode">Startup and Redeploy Mode</a></td>
    <td>automatic</td></tr>
</deftable-childtags>

<example title="Example: explicit host">
&lt;host host-name="www.foo.com"&gt;
  &lt;host-alias&gt;foo.com&lt;/host-alias&gt;
  &lt;host-alias&gt;web.foo.com&lt;/host-alias&gt;

  &lt;root-directory&gt;/opt/www/www.foo.com&lt;/root-directory&gt;

  &lt;web-app id="/" document-directory="webapps/ROOT"&gt;
    
  &lt;/web-app&gt;
  ...
&lt;/host&gt;
</example>

<example title="Example: regexp host">
&lt;host regexp="([^.]+)\.foo\.com"&gt;
  &lt;host-name&gt;${host.regexp[1]}.foo.com&lt;/host-name&gt;

  &lt;root-directory&gt;/var/www/hosts/www.${host.regexp[1]}.com&lt;/root-directory&gt;

  ...
&lt;/host&gt;
</example>

<p>It is recommended that any &lt;host&gt; using a regexp include
a &lt;host-name&gt; to set the canonical name for the host.</p>

</defun>

<defun title="&lt;host-default>" version="Resin 3.0">
<parents>cluster</parents>

<p>Defaults for a virtual host.</p>

<p>The host-default can contain any of the host configuration tags.
It will be used as defaults for any virtual host.</p>

</defun>

<defun title="&lt;host-deploy>" version="Resin 3.0.4">
<parents>cluster</parents>

<p>Configures a deploy directory for virtual host.</p>

<p>The host-deploy will add an EL variable ${name}, referring to
the name of the host jar file.</p>

<deftable-childtags>
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr><td>path</td>
    <td>path to the deploy directory</td>
    <td>required</td></tr>
<tr><td>expand-path</td>
    <td>path to the expansion directory</td>
    <td>path</td></tr>
<tr><td>host-default</td>
    <td>defaults for the expanded host</td></tr>
<tr><td>host-name</td>
    <td>the host name to match</td>
    <td>${name}</td></tr>
</deftable-childtags>

</defun>

<defun title="&lt;ignore-client-disconnect>" version="Resin 3.1">
<parents>cluster</parents>
<default>true</default>

<p>ignore-client-disconnect configures whether Resin should ignore
disconnection exceptions from the client, or if it should send those
exceptions to the application.</p>

<def title="&lt;ignore-client-disconnect> schema">
element ignore-client-disconnect {
  r_boolean-Type
}
</def>

</defun>

<defun title="&lt;invocation-cache-size>" version="Resin 3.1">
<parents>cluster</parents>
<default>8192</default>

<p>Configures the number of entries in the invocation cache.
The invocation cache is used to store pre-calculated servlet and filter
chains from the URLs.  It's also used as the basis for proxy caching.</p>

<def title="&lt;invocation-cache-size> schema">
element invocation-cache-size {
  r_int-Type
}
</def>

</defun>

<defun title="&lt;invocation-cache-max-url-length>" version="Resin 3.1">
<parents>cluster</parents>
<default>256</default>

<p>Configures the longest entry cacheable in the invocation cache.
It is used to avoid certain types of denial-of-service attacks.</p>

<def title="&lt;invocation-cache-max-url-length> schema">
element invocation-cache-max-url-length {
  r_int-Type
}
</def>

</defun>

<defun title="&lt;persistent-store>" version="Resin 3.0.8">
<parents>cluster</parents>

<p>Defines the cluster-aware persistent store used for
sharing distributed sessions.  The allowed types are "jdbc", "cluster"
and "file".  The "file" type is only recommended in single-server
configurations.</p>

<p>The &lt;persistent-store&gt; configuration is in the &lt;server&gt; level
because it needs to share update information across the
active cluster and the &lt;cluster&gt; definition is at the &lt;server&gt; level.
Sessions activate the persistent store with the &lt;use-persistent-store&gt;
tag of the &lt;session-config&gt;.</p>

<p>See <a href="resin-clustering.xtp">Persistent sessions</a> for more details.</p>

<deftable title="&lt;persistent-store> Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>init</td>
  <td>initialization parameters for the persistent-store</td>
  <td></td>
</tr>
<tr>
  <td>type</td>
  <td>cluster, jdbc, or file</td>
  <td>required</td>
</tr>
</deftable>

<def title="&lt;persistent-store> schema">
element persistent-store {
  type
  &amp; init?
}
</def>

<s2 name="cluster-store" title="cluster store">

<p>The cluster store shares copies of the sessions on multiple servers.
The original server is used as the primary, and is always more efficient
than the backup servers.  In general, the cluster store is preferred because
it is more scalable, and with the "triplicate" attribute, the
most reliable..</p>

<deftable title="cluster tags">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>always-load</td>
  <td>Always load the value</td>
  <td>false</td>
</tr>
<tr>
  <td>always-save</td>
  <td>Always save the value</td>
  <td>false</td>
</tr>
<tr>
  <td>max-idle-time</td>
  <td>How long idle objects are stored (session-timeout will invalidate
items earlier)</td>
  <td>24h</td>
</tr>
<tr>
  <td>path</td>
  <td>Directory to store the objects</td>
  <td>required</td>
</tr>
<tr>
  <td>triplicate</td>
  <td>Saves three copies of all distributed objects.</td>
  <td>false</td>
</tr>
<tr>
  <td>wait-for-acknowledge</td>
  <td>Requires the sending server to wait for all acks.</td>
  <td>false</td>
</tr>
</deftable>

<def title="cluster schema">
element persistent-store {
  type { "cluster "}

  element init {
    always-load?
    &amp; always-save?
    &amp; max-idle-time?
    &amp; triplicate?
    &amp; wait-for-acknowledge?
  }
}
</def>

<example title="Example: cluster store">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
&lt;cluster&gt;
  &lt;server id="a" address="192.168.0.1" port="6800"/&gt;
  &lt;server id="b" address="192.168.0.2" port="6800"/&gt;

  &lt;persistent-store type="cluster"&gt;
    &lt;init&gt;
      &lt;triplicate&gt;true&lt;/triplicate&gt;
    &lt;/init&gt;
  &lt;/persistent-store&gt;

  &lt;web-app-default&gt;
    &lt;session-config use-persistent-store="true"/&gt;
  &lt;/web-app-default&gt;
&lt;/cluster&gt;
&lt;/resin&gt;
</example>

</s2>

<s2 title="jdbc store">

<p>The JDBC store saves sessions in a JDBC database.  Often, this will be
a dedicated database to avoid overloading the main database.</p>

<deftable title="jdbc store Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>always-load</td>
  <td>Always load the value</td>
  <td>false</td>
</tr>
<tr>
  <td>always-save</td>
  <td>Always save the value</td>
  <td>false</td>
</tr>
<tr>
  <td>blob-type</td>
  <td>Schema type to store values</td>
  <td>from JDBC meta info</td>
</tr>
<tr>
  <td>data-source</td>
  <td>The JDBC data source</td>
  <td>required</td>
</tr>
<tr>
  <td>table-name</td>
  <td>Database table</td>
  <td>persistent_session</td>
</tr>
<tr>
  <td>max-idle-time</td>
  <td>How long idle objects are stored</td>
  <td>24h</td>
</tr>
</deftable>

<example title="Example: jdbc-store">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
&lt;cluster&gt;
  &lt;server id="a" address="192.168.0.1" port="6800"/&gt;
  &lt;server id="b" address="192.168.0.2" port="6800"/&gt;

  &lt;persistent-store type="jdbc"&gt;
    &lt;init&gt;
      &lt;data-source&gt;jdbc/session&lt;/data-source&gt;

      &lt;max-idle-time&gt;24h&lt;/max-idle-time&gt;
    &lt;/init&gt;
  &lt;/persistent-store&gt;

  &lt;web-app-default&gt;
    &lt;session-config use-persistent-store="true"/&gt;
  &lt;/web-app-default&gt;
&lt;/cluster&gt;
&lt;/resin&gt;
</example>

</s2>

<s2 title="file store">

<p>The file store is a persistent store for development and testing or
for single servers.  Since it is not aware of the clusters, it cannot
implement true distributed objects.</p>

<deftable title="file tags">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>always-load</td>
  <td>Always load the value</td>
  <td>false</td>
</tr>
<tr>
  <td>always-save</td>
  <td>Always save the value</td>
  <td>false</td>
</tr>
<tr>
  <td>max-idle-time</td>
  <td>How long idle objects are stored</td>
  <td>24h</td>
</tr>
<tr>
  <td>path</td>
  <td>Directory to store the sessions</td>
  <td>required</td>
</tr>
</deftable>

</s2>

</defun>

<defun title="&lt;ping>" occur="*" version="Resin 3.0">
<parents>cluster</parents>

<p>Starts a thread that periodically makes a request to the server, and
restarts Resin if it fails.  This facility is used to increase server
reliability - if there is a problem with the server (perhaps from a deadlock or
an exhaustion of resources), the server is restarted.</p>

<p>A failure occurs if a request to the url returns an HTTP status that is
not 200.</p>

<p>Since the local process is restarted, it does not make sense to specify a
url that does not get serviced by the instance of Resin that has the ping
configuration.  Most configurations use url's that specify 'localhost' as
the host.</p>

<p>This pinging only catches some problems because it's running in the
same process as Resin itself.  If the entire JDK freezes, this
thread will freeze as well.  Assuming the JDK doesn't freeze, the
PingThread will catch errors like deadlocks.</p>

<deftable title="&lt;ping> Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>url</td>
  <td>A url to ping.</td>
  <td>required</td>
</tr>
<tr>
  <td>sleep-time</td>
  <td>Time to wait between pings.  The first ping is always 15m after the server starts, this is for subsequent pings.</td>
  <td>15m</td>
</tr>
<tr>
  <td>try-count</td>
  <td>If a ping fails, number of times to retry before giving up and restarting</td>
  <td>required</td>
</tr>
<tr>
  <td>retry-time</td>
  <td>time between retries</td>
  <td>1s</td>
</tr>
<tr>
  <td>socket-timeout</td>
  <td>time to wait for server to start responding to the tcp connection before giving up</td>
  <td>10s</td>
</tr>
</deftable>

<example title="Example: resin.conf - simple usage of server ping">
&lt;resin xmlns="http://caucho.com/ns/resin"
       xmlns:resin="http://caucho.com/ns/resin/core"&gt;
    &lt;cluster id="app-tier"&gt;
        &lt;ping url="http://localhost/"/&gt;
        ...
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

<example title="Example: resin.conf - configured usage of server ping">
&lt;resin xmlns="http://caucho.com/ns/resin"
       xmlns:resin="http://caucho.com/ns/resin/core"&gt;
    ...
    &lt;cluster id="app-tier"&gt;
        &lt;ping&gt;
            &lt;url&gt;http://localhost:8080/index.jsp&lt;/url&gt;
            &lt;url&gt;http://localhost:8080/webapp/index.jsp&lt;/url&gt;
            &lt;url&gt;http://virtualhost/index.jsp&lt;/url&gt;
            &lt;url&gt;http://localhost:443/index.jsp&lt;/url&gt;

            &lt;sleep-time&gt;5m&lt;/sleep-time&gt;
            &lt;try-count&gt;5&lt;/try-count&gt;
    
            &lt;!-- a very busy server --&gt;
            &lt;socket-timeout&gt;30s&lt;/socket-timeout&gt;
        &lt;/ping&gt;
      ...
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

<p>
The class that corresponds to &lt;ping&gt; is 
<a href="javadoc|com.caucho.server.admin.PingThread|">PingThread</a>.  
</p>

<s2 title="Mail notification when ping fails">

<p>A refinement of the ping facility sends an email when the server is
restarted.</p>

<example title="resin.conf - mail notification when ping fails">
&lt;resin xmlns="http://caucho.com/ns/resin"
       xmlns:resin="http://caucho.com/ns/resin/core"&gt;
  ...
  &lt;cluster id="web-tier"&gt;
    &lt;ping resin:type="com.caucho.server.admin.PingMailer"&gt;
      &lt;url&gt;http://localhost:8080/index.jsp&lt;/url&gt;
      &lt;url&gt;http://localhost:8080/webapp/index.jsp&lt;/url&gt;

      &lt;mail-to&gt;fred@hogwarts.com&lt;/mail-to&gt;
      &lt;mail-from&gt;resin@hogwarts.com&lt;/mail-from&gt;
      &lt;mail-subject&gt;Resin ping has failed for server ${'${'}server.name}&lt;/mail-subject&gt;
    &lt;/ping&gt;
    ...
  &lt;/server&gt;
&lt;/resin&gt;
</example>

<p>
The default behaviour for sending mail is to contact a SMTP server at host 127.0.0.1 (the localhost) on port 25.
System properties are used to configure a different SMTP server.
</p>

<example title="resin.conf - smtp server configuration">
  &lt;system-property mail.smtp.host="127.0.0.1"/&gt;
  &lt;system-property mail.smtp.port="25"/&gt;
</example>

</s2>

</defun>

<defun title="Resource Tags" version="Resin 3.1">
<parents>cluster</parents>

<p>All <a href="env-tags.xtp">Environment tags</a> are
available to the &lt;cluster&gt;.  For example,
resources like &lt;database&gt;.</p>

<example title="Example: cluster environment">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="app-tier"&gt;
        &lt;database jndi-name="jdbc/test"&gt;
            &lt;driver type="org.postgresql.Driver"&gt;
                &lt;url&gt;jdbc:postgresql://localhost/test&lt;/url&gt;
                &lt;user&gt;caucho&lt;/user&gt;
            &lt;/driver&gt;
        &lt;/database&gt;

        &lt;server id="a" ...&gt;
          ...

        &lt;host host-name="www.foo.com"&gt;
          ...
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;rewrite-dispatch>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;rewrite-dispatch&gt; defines a set of rewriting rules for
dispatching and forwarding URLs.  Applications can use these rules
to redirect old URLs to their new replacements.</p>

<p>See <a href="rewrite-tags.xtp">rewrite-dispatch</a> for more
details.</p>

<example title="rewrite-dispatch">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;

        &lt;rewrite-dispatch&gt;
            &lt;redirect regexp="^http://www.foo.com"
                      target="http://bar.com/foo"/&gt;
        &lt;/rewrite-dispatch&gt;
  
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;root-directory>" version="Resin 3.1">
<parents>cluster</parents>
<default>The root-directory of the &lt;resin&gt; tag.</default>

<p>&lt;root-directory&gt; configures the root directory for files
within the cluster.  All paths in the &lt;cluster&gt; will be relative
to the root directory.</p>

<def title="&lt;root-directory> schema">
element root-directory {
  r_path-Type
}
</def>

<example title="Example: cluster root-directory">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="app-tier"&gt;
        &lt;root-directory&gt;/var/www/app-tier&lt;/root-directory&gt;

        &lt;server id="a" ...&gt;

        &lt;host host-name="www.foo.com"&gt;
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;server>" version="Resin 3.1">
<parents>cluster</parents>

<p>The &lt;server> tag configures a JVM instance in
the cluster.  Each &lt;server&gt; is uniquely identified by
its <var>id</var> attribute.  The <var>id</var> will match
the -server-id command line argument.</p>

<p>See the full <a href="server-tags.xtp">server configuration</a>
for more details of the &lt;server> tag and its children.</p>

<p>The current server is managed with a
<a href="javadoc|com.caucho.management.server.ServerMXBean">ServerMXBean</a>.
The <g>ObjectName</g> is <var>resin:type=Server</var>.</p>

<p>Peer servers are managed with 
<a href="javadoc|com.caucho.management.server.ServerConnectorMXBean">ServerConnectorMXBean</a>. The ObjectName is <var>resin:type=ServerConnector,name=server-id</var>.</p>

<deftable title="&lt;server> Attributes">
<tr>
  <th>Attribute</th>
  <th>Description</th>
  <th>Default</th>
</tr>
<tr>
  <td>address</td>
  <td>IP address of the cluster port</td>
  <td>127.0.0.1</td>
</tr>
<tr>
  <td>bind-ports-after-start</td>
  <td>If true, listen to the ports only after all initialization has
completed, allowing load-balance failover.</td>
  <td>true</td>
</tr>
<tr>
  <td>cluster-port</td>
  <td>Configures the cluster port in detail, allowing for customization
of timeouts, etc.</td>
  <td></td>
</tr>
<tr>
  <td>group-name</td>
  <td>Used by the watchdog to switch setgid before starting the Resin
JVM instance for security.</td>
  <td></td>
</tr>
<tr>
  <td>http</td>
  <td>Adds a HTTP port (see <a href="port-tags.xtp">port tags</a>)</td>
  <td></td>
</tr>
<tr>
  <td>id</td>
  <td>Unique server identifier</td>
  <td>required</td>
</tr>
<tr>
  <td>java-exe</td>
  <td>The specific Java executable for the watchdog
to launch the JVM</td>
  <td>java</td>
</tr>
<tr>
  <td>jvm-arg</td>
  <td>Adds a JVM argument when the watchdog launches Resin.</td>
  <td></td>
</tr>
<tr>
  <td>jvm-classpath</td>
  <td>Adds a JVM classpath when the watchdog launches Resin.</td>
  <td></td>
</tr>
<tr>
  <td>keepalive-connection-time-max</td>
  <td>The total time a connection can be used for requests and keepalives</td>
  <td>10min</td>
</tr>
<tr>
  <td>keepalive-max</td>
  <td>The maximum keepalives enabled at one time.</td>
  <td>128</td>
</tr>
<tr>
  <td>keepalive-select-enable</td>
  <td>Enables epoll/select for keepalive requests to reduce threads (unix only)</td>
  <td>true</td>
</tr>
<tr>
  <td>keepalive-timeout</td>
  <td>Timeout for a keepalive to wait for a new request</td>
  <td>15s</td>
</tr>
<tr>
  <td>load-balance-connect-timeout</td>
  <td>How long the load-balancer should wait for a connection to this server</td>
  <td>5s</td>
</tr>
<tr>
  <td>load-balance-idle-time</td>
  <td>How long the load balancer can keep an idle socket open to this server (see keepalive-timeout)</td>
  <td>keepalive-time - 2s</td>
</tr>
<tr>
  <td>load-balance-recover-time</td>
  <td>How long the load balancer should treat this server as dead after a failure before retrying</td>
  <td>15s</td>
</tr>
<tr>
  <td>load-balance-socket-timeout</td>
  <td>timeout for the load balancer reading/writing to this server</td>
  <td>65s</td>
</tr>
<tr>
  <td>load-balance-warmup-time</td>
  <td>Warmup time for the load-balancer to throttle requests before sending the full load</td>
  <td>60s</td>
</tr>
<tr>
  <td>load-balance-weight</td>
  <td>relative weight used by the load balancer to send traffic to this server</td>
  <td>100</td>
</tr>
<tr>
  <td>memory-free-min</td>
  <td>minimum memory allowed for the JVM before Resin forces a restart</td>
  <td>1M</td>
</tr>
<tr>
  <td>ping</td>
  <td>Configures a periodic ping of the server to force restarts when non-responsive</td>
  <td></td>
</tr>
<tr>
  <td>port</td>
  <td>Configures the cluster port (shortcut for &lt;cluster-port>)</td>
  <td>6800</td>
</tr>
<tr>
  <td>protocol</td>
  <td>Adds a custom socket protocol, e.g. for IIOP or SNMP.</td>
  <td></td>
</tr>
<tr>
  <td>shutdown-wait-max</td>
  <td>The maximum of time to wait for a graceful Resin shutdown before forcing a close</td>
  <td>60s</td>
</tr>
<tr>
  <td>socket-timeout</td>
  <td>The read/write timeout for the socket</td>
  <td>65s</td>
</tr>
<tr>
  <td>thread-max</td>
  <td>The maximum number of threads managed by Resin (JVM threads will be larger because of non-Resin threads)</td>
  <td>4096</td>
</tr>
<tr>
  <td>thread-executor-thread-max</td>
  <td>Limits the threads allocated to application ScheduledExecutors from Resin</td>
  <td></td>
</tr>
<tr>
  <td>thread-idle-max</td>
  <td>Maximum number of idle threads in the thread pool</td>
  <td>10</td>
</tr>
<tr>
  <td>thread-idle-min</td>
  <td>Minimum number of idle threads in the thread pool</td>
  <td>5</td>
</tr>
<tr>
  <td>user-name</td>
  <td>The setuid user-name for the <a href="resin-watchdog.xtp">watchdog</a>
when launching Resin for Unix security.</td>
  <td></td>
</tr>
<tr>
  <td>watchdog-jvm-arg</td>
  <td>Additional JVM arguments when launching the watchdog manager</td>
  <td></td>
</tr>
<tr>
  <td>watchdog-port</td>
  <td>The port for the watchdog-manager to listen for start/stop/status
requests</td>
  <td>6700</td>
</tr>
</deftable>

<def title="&lt;server> schema">
element server {
  attribute id { string }
  &amp; address?
  &amp; bind-ports-after-start?
  &amp; cluster-port*
  &amp; group-name?
  &amp; http*
  &amp; java-exe?
  &amp; jvm-arg?
  &amp; jvm-classpath?
  &amp; keepalive-connection-time-max?
  &amp; keepalive-max?
  &amp; keepalive-select-enable?
  &amp; keepalive-timeout?
  &amp; load-balance-connect-timeout?
  &amp; load-balance-idle-time?
  &amp; load-balance-recover-time?
  &amp; load-balance-socket-timeout?
  &amp; load-balance-warmup-time?
  &amp; load-balance-weight?
  &amp; memory-free-min?
  &amp; ping?
  &amp; port?
  &amp; protocol?
  &amp; shutdown-wait-max?
  &amp; socket-timeout?
  &amp; thread-max?
  &amp; thread-executor-task-max?
  &amp; thread-idle-max?
  &amp; thread-idle-min?
  &amp; user-name?
  &amp; watchdog-jvm-arg*
  &amp; watchdog-port?
}
</def>

<example title="Example: server">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;server id="a" address="192.168.0.10" port="6800"&gt;
          &lt;http port="8080"/&gt;
        &lt;/server&gt;

        &lt;server id="b" address="192.168.0.11" port="6800"&gt;
          &lt;http port="8080"/&gt;
        &lt;/server&gt;

        &lt;server id="c" address="192.168.0.12" port="6800"&gt;
          &lt;http port="8080"/&gt;
        &lt;/server&gt;

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

</defun>

<defun title="&lt;server-default>" version="Resin 3.1">
<parents>cluster</parents>

<p>Defines default values for all &lt;server&gt; instances. See
<a href="server-tags.xtp">&lt;server> configuration</a> for more details.</p>

<example title="Example: server">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;server-default&gt;
            &lt;server-port&gt;6800&lt;/server-port&gt;

            &lt;http port="8080"/&gt;
        &lt;/server-default&gt;

        &lt;server id="a" address="192.168.0.10"/&gt;
        &lt;server id="b" address="192.168.0.11"/&gt;
        &lt;server id="c" address="192.168.0.12"/&gt;

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

</defun>

<defun title="&lt;server-header>" version="Resin 3.1">
<parents>cluster</parents>
<default>Resin/3.1.x</default>

<p>Configures the HTTP Server: header which Resin sends back to any
HTTP client.</p>

<def title="&lt;server-header> schema">
element server-header {
  string
}
</def>

<example title="server-header">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;server-header&gt;MyServer/1.0&lt;/server-header&gt;
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;session-cookie>" version="Resin 3.1">
<parents>cluster</parents>
<default>JSESSIONID</default>

<p>Configures the cookie used for servlet sessions.</p>

<def title="&lt;session-cookie> schema">
element session-cookie {
  string
}
</def>

</defun>

<defun title="&lt;session-sticky-disable>" version="Resin 3.1">
<parents>cluster</parents>
<default>false</default>

<p>Disables sticky sessions from the load balancer.</p>

<def title="&lt;session-sticky-disable> schema">
element session-sticky-disable {
  r_boolean-Type
}
</def>

</defun>

<defun title="&lt;session-url-prefix>" version="Resin 3.1">
<parents>cluster</parents>
<default>;jsessionid=</default>

<p>Configures the URL prefix used for session rewriting.</p>

<note>Session rewriting is discouraged as a potential security issue.</note>

<def title="&lt;session-cookie> schema">
element session-cookie {
  string
}
</def>

</defun>

<defun title="&lt;ssl-session-cookie>" version="Resin 3.1">
<parents>cluster</parents>
<default>value of session-cookie</default>

<p>Defines an alternative session cookie to be used for a SSL
connection.  Having two separate cookies increases security.</p>

<def title="&lt;session-cookie> schema">
element ssl-session-cookie {
  string
}
</def>

<example title="Example: ssl-session-cookie">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="web-tier"&gt;
        &lt;ssl-session-cookie&gt;SSLJSESSIONID&lt;/ssl-session-cookie&gt;
        ...
    &lt;/cluster&gt;
&lt;/resin&gt;
</example>

</defun>

<defun title="&lt;url-character-encoding>" version="Resin 3.1">
<parents>cluster</parents>
<default>UTF-8</default>

<p>Defines the character encoding for decoding URLs.</p>

<p>The HTTP specification does not define the character-encoding for
URLs, so the server must make assumptions about the encoding.</p>

<def title="&lt;url-character-encoding> schema">
element url-character-encoding {
  string
}
</def>

</defun>

<defun title="&lt;web-app-default>" version="Resin 3.1">
<parents>cluster</parents>

<p>&lt;web-app-default&gt; defines default values for any <g>web-app</g> in
the cluster.</p>

<example title="Example: web-app-default">
&lt;resin xmlns="http://caucho.com/ns/resin"&gt;
    &lt;cluster id="app-tier"&gt;

        &lt;web-app-default&gt;
            &lt;servlet servlet-name="resin-php"
                     servlet-class="com.caucho.quercus.servlet.QuercusServlet"/&gt;

            &lt;servlet-mapping url-pattern="*.php"
                             servlet-name="resin-php"/&gt;
        &lt;/web-app-default&gt;

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

</defun>

</body>
</document>
