<cluster> configures a set of servers used for load-balancing and for sharing distributed sessions.

<resin xmlns="http://caucho.com/ns/resin">
  <cluster id="app-tier">
    <server id="a" address="192.168.0.1"/>
    <server id="b" address="192.168.0.2"/>

    <host id="">
      <web-app-deploy path="webapps"/>
    </host>
  </cluster>
</resin>

For reliability, Resin periodically checks the amount of free memory available. When the free memory drops below <min-free-memory>, even after garbage collection, Resin will force a JVM restart.

In general, application developers should use a heap profiler to eliminate memory leaks and OutOfMemoryErrors. Because an OutOfMemoryError can cause severe problems with the application, Resin detects the low memory before those errors can be thrown.

<resin> is the top-level configuration tag for the resin.conf file. The <resin> tag needs to specify the Resin namespace, to allow for validation of the configuration file.

The environment of the top-level <resin> is the global classpath. This environment can be important for <log> configuration for threads which run with using only the global class loader. Because the <resin> environment does not have a dynamic class loader, dynamically loaded classes, like custom jars in resin/lib are not available.

<resin xmlns="http://caucho.com/ns/resin">
  <cluster id="web-tier">
    <server id="">
      <http address="*" port="8080"/>
    </server id="">

    <resin:import path="app-default.xml"/>

    <host id=""/>
      <web-app id="/"/>
    </host>
  </cluster>
</resin>

Specifies the root directory for the <server> and <host> contexts. All EL-style directory paths are relative to the root-directory.

Enable the use of the security manager for the JVM.

<resin xmlns="http://caucho.com/ns/resin"
       xmlns:resin="http://caucho.com/ns/resin/core">

  ...
  <security-manager/>
  ...

See also:

• Security Manager

Add one or more security providers. Each entry specifies the name of a security provider class. The name is used to instantiate an instance of the object, which is then passed to java.security.Security.

<resin xmlns="http://caucho.com/ns/resin"
       xmlns:resin="http://caucho.com/ns/resin/core">

  ...

  <security-provider>
    com.sun.net.ssl.internal.ssl.Provider
  </security-provider>
  <security-provider>
    example.MyProvider
  </security-provider>

  ...

Main configuration for the server, configuring ports, threads and virtual hosts.

• Common resources for all virtual hosts and web-apps.
• Thread pooling
• HTTP and SRUN/Cluster ports
• Caching
• virtual host configuration and common web-app-default

The <server> will generally contain a <class-loader> configuration which loads the resin/lib jars dynamically, allowing for system-wide jars to be dropped into resin/lib. <server> configures the main dynamic environment. Database pools common to all virtual hosts, for example, should be configured in the <server> block.

The <server> configures the <thread-pool> and a set of <http> and <srun> ports which share the thread pool. Requests received on those ports will use worker threads from the thread pool.

<server>
  ...
  <alternate-session-url-prefix>/~J=</alternate-session-url-prefix>
  ...

EL variables and functions

Configures the maximum time Resin will wait for the server to shutdown gracefully before forcing an exit.

<thread-pool> configures the thread pool shared among all ports.

<thread-max> is the absolute maximum number of connection worker threads allowed. <thread-max> may be limited by OS/JVM restrictions, especially the stack size. -Xss and/or ulimit -s may be required for large numbers of threads, e.g. "ulimit -s 2048" on some versions of Linux would allow for 1024 total threads in the JVM.

<spare-thread-min> configures Resin's adaptive thread pooling. Resin tries to keep <spare-thead-min> idle threads available at all time. Sites with large spikes in connection loads may need to increase the <spare-thread-min> value.

Note: at present, this directive is deprecated because of timing issues with log file creation and ownership. It is recommended that you use some other method to remap port 80 to port 8080.

Configures the Unix setuid user name used after Resin binds the reserved ports as root.