Clustering

Revision as of 09:56, 14 January 2009

A Cluster is a collection of Resin JVMs all running the same application. The <cluster> directive configures the cluster.

See Also

• <cluster>
• Sticky Sessions

Selecting a Backend Server

In testing situations, it can be important to select a particular backend server when making a request of the front-end server. The easiest solution is to take advantage of sticky sessions and use the ";jsessionid=" url.

Supposed in the following cluster of three backend servers, you wanted to test the second one, i.e. the one listening to 192.168.0.11. You could send a request to "/test.jsp;jsessionid=bXXXX".

resin.xml

<resin xmlns="http://caucho.com/ns/resin">
   ...
  <cluster>
    <server id="a" address="192.168.0.10" port="6800"/>
    <server id="b" address="192.168.0.11" port="6801"/>
    <server id="c" address="192.168.0.12" port="6802"/>
     ...
   </cluster>
 </resin>

The 'b' will select the second server. Because that request uses URL rewriting and also because "bXXXX" value is too short, Resin will generate a new session instead of using the cookie value of "bXXXX".

Note, the non-reuse of the session value "bXXXX" is affected by the <reuse-session-id> configuration.