Selecting a Backend Server

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Revision as of 05:00, 17 November 2005

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".

<cluster>
  <srun id="a" host="192.168.0.10" port="6802"/>
  <srun id="b" host="192.168.0.11" port="6803"/>
  <srun id="c" host="192.168.0.12" port="6804"/>
</cluster>

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.