{"type":"doc","content":[{"type":"paragraph","content":[{"text":"If XPLG cluster is running with multiple UI nodes, it is recommended to install a Load Balancer in front of the XPLG cluster so that users will be automatically redirected to the UI nodes.","type":"text"}]},{"type":"heading","attrs":{"level":3},"content":[{"text":"The following example explains how to set up Apache Httpd server as a load Load Balancer:","type":"text","marks":[{"type":"strong"}]}]},{"type":"orderedList","attrs":{"order":1},"content":[{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Set up Apache httpd server on Linux.","type":"text"}]}]},{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Download the latest version of ","type":"text"},{"text":"mod_jk","type":"text","marks":[{"type":"link","attrs":{"href":"http://tomcat.apache.org/connectors-doc/"}}]},{"text":" from Apache web site. Copy this file into the Apache modules/ directory and rename it to mod_jk.so.","type":"text"}]}]},{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Configure Apache","type":"text","marks":[{"type":"strong"}]},{"text":":","type":"text"}]},{"type":"orderedList","attrs":{"order":1},"content":[{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Edit the file ","type":"text"},{"text":"httpd.conf ","type":"text","marks":[{"type":"strong"}]},{"text":"(Apache configuration path usually: /etc/httpd/conf/httpd.conf)","type":"text"},{"type":"hardBreak"},{"text":"Note that the default port is usually 80, change it if needed but make sure that the ports you use are available.","type":"text"},{"type":"hardBreak"},{"type":"hardBreak"},{"text":"Add the following right after the other LoadModule directives: ","type":"text"},{"type":"hardBreak"},{"text":"LoadModule jk_module modules/mod_jk.so","type":"text"},{"type":"hardBreak"},{"text":"Add the following at the end of the httpd.conf file:","type":"text"},{"type":"hardBreak"},{"text":"# Where to find workers.properties","type":"text"},{"type":"hardBreak"},{"text":"JkWorkersFile /etc/httpd/conf/workers.properties","type":"text"},{"type":"hardBreak"},{"text":"# Where to put jk shared memory","type":"text"},{"type":"hardBreak"},{"text":"JkShmFile /var/log/httpd/mod_jk.shm","type":"text"},{"type":"hardBreak"},{"text":"# Where to put jk logs","type":"text"},{"type":"hardBreak"},{"text":"JkLogFile /var/log/httpd/mod_jk.log","type":"text"},{"type":"hardBreak"},{"text":"# Set the jk log level [debug/error/info]","type":"text"},{"type":"hardBreak"},{"text":"JkLogLevel info","type":"text"},{"type":"hardBreak"},{"type":"hardBreak"},{"type":"hardBreak"},{"text":"# Select the timestamp log format","type":"text"},{"type":"hardBreak"},{"text":"JkLogStampFormat \"[%a %b %d %H:%M:%S %Y] \"","type":"text"},{"type":"hardBreak"},{"text":"JkMount /* balancer","type":"text"},{"type":"hardBreak"},{"text":"JkMount /*/* balancer","type":"text"}]}]},{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Create workers.properties","type":"text","marks":[{"type":"strong"}]},{"type":"hardBreak"},{"text":"The worker.properties file should be located in the /etc/httpd/conf/ directory. In the file you should have the following parameters set for the UI1, UI2 nodes:","type":"text"},{"type":"hardBreak"},{"text":"Define the list of workers that will be used","type":"text"},{"type":"hardBreak"},{"text":"worker.list=balancer","type":"text"},{"type":"hardBreak"},{"text":"worker.balancer.type=lb","type":"text"},{"type":"hardBreak"},{"text":"worker.balancer.balance_workers=ui1,ui2","type":"text"},{"type":"hardBreak"},{"text":"worker.balancer.method=B","type":"text"},{"type":"hardBreak"},{"text":"# Specifies whether requests with SESSION ID's","type":"text"},{"type":"hardBreak"},{"text":"# should be routed back to the same #Tomcat worker","type":"text"},{"type":"hardBreak"},{"text":"worker.balancer.sticky_session=True","type":"text"},{"type":"hardBreak"},{"text":"# Define UI1","type":"text"},{"type":"hardBreak"},{"text":"worker.ui1.port=","type":"text"},{"type":"hardBreak"},{"text":"worker.ui1.host= ","type":"text"},{"type":"hardBreak"},{"text":"worker.ui1.type=ajp13","type":"text"},{"type":"hardBreak"},{"text":"worker.ui1.lbfactor=1","type":"text"},{"type":"hardBreak"},{"text":"# Define UI2","type":"text"},{"type":"hardBreak"},{"text":"worker.ui2.port=","type":"text"},{"type":"hardBreak"},{"text":"worker.ui2.host= ","type":"text"},{"type":"hardBreak"},{"text":"worker.ui2.type=ajp13","type":"text"},{"type":"hardBreak"},{"text":"worker.ui2.lbfactor=1","type":"text"},{"type":"hardBreak"}]}]}]}]},{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Configure Tomcat on each of the UI nodes","type":"text","marks":[{"type":"strong"}]},{"text":":","type":"text"}]},{"type":"orderedList","attrs":{"order":1},"content":[{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"On each of the","type":"text"},{"text":" ","type":"text","marks":[{"type":"strong"}]},{"text":"XPLG UI nodes, edit the file /ServletContainer/conf/server.xml","type":"text"}]}]},{"type":"listItem","content":[{"type":"paragraph","content":[{"text":"Go to the following XML Tag:","type":"text"},{"type":"hardBreak"},{"text":"","type":"text"},{"type":"hardBreak"},{"text":"","type":"text"},{"type":"hardBreak"},{"type":"hardBreak"},{"text":"Set up the port to the same as ","type":"text"},{"type":"hardBreak"},{"text":"Go to the following Engine tag to set the ui node name must be like the one in the Apache workers.properties used name:","type":"text"},{"type":"hardBreak"},{"text":"