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Download and install Okapi Longhorn as shown here: http://okapiframework.org/wiki/index.php?title=Longhorn#Download_and_Installation.
If you have a working and running Tomcat that has autoDeploy set to "true" in the /etc/tomcat9/server.xml file, than to deploy your okapi-longhorn.war file you can simply copy it to the webapps-folder of your Tomcat installation (on Ubuntu this is located under /var/lib/tomcat9/webapps). You may have to set the file access rights of the war file, so that Tomcat can handle the file and you may need to restart Tomcat.
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-Djdk.xml.xpathExprOpLimit=2000200
For doing this, open the setenv.sh file in the bin directory of the CATALINA_HOME directory of your tomcat installation.
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Translate5 Configuration of the Okapi Plug-In
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