The QES (evaluator) is implemented as a stateful web service. It implements the physical query algebra and query processing semantics based on the classical Iterator Model. It evaluates a XML-formatted query partition sent to it by the co-ordinator.
The installation process of the QES is simplified by the provision of an Apache Ant build file which contains targets which will automatically install and deploy the QES on Tomcat.
Installing Apache Axis is not necessary. OGSA-DQP is packaged with the Axis libraries required by the evaluator.
1. The following environment variables should have been set during the installation of Tomcat:
Ensure that these environment variables have been set before proceeding.
2. Run the following from within the evaluator directory of the OGSA-DQP distribution:
$ ant deploy
This will create a WAR file for the QES and deploy it on Tomcat.
3. Start-up Tomcat.
If these steps are performed successfully, the result is that the QES is deployed on Tomcat, and you should be able to view the WSDL at:
http://<host>:<port>/dqp-evaluator/services/QueryEvaluationService