A high availability license is required.

To set up an active-passive failover cluster using Microsoft Windows Failover Cluster Services:

1. Install a Windows Failover Cluster according to the install guide provided on Microsoft Technet: Failover clustering deployment.
   Note the following:
   1. The common fileshare that the Windows Failover Clustering Services describes is not needed.
   2. The service that needs to be monitored for failover by Windows Cluster Service is the Apache Tomcat Service.

To install identical Tomcat nodes:

1. Install a complete PRIME system on one node, including Tomcat, Java, PRIME applications, and database connection.
2. Copy the setup from the first node to other nodes, to make sure that all components are exactly the same on all nodes.

For the general requirements for PRIME, see PRIME requirements and interoperability.

The following additional components are required:

• Apache HTTP Server 2.4 (Tested on Version 2.4.17)
• mod_jk 1.2 (tested on Version 1.2.41)

Supported platforms for the high availability configuration:

• Windows 7, Windows 8.1, Windows Server 2008/2008 R2/ 2012/ 2012 R2
• Linux
  
  

For load balancing with the Apache HTTP Server, the module mod_jk is recommended. It is also possible to use the module mod_proxy.

To do a standard Apache HTTP server setup:

1. Download and install the Apache HTTP server. See Apache HTTP Server Project for downloads and install guide.
   
   Example:
   With the Apache Lounge Distribution, the file unzips to the folder C:\Apache24. The Windows service can be installed with the following command:

   Example: Command for installing Apache HTTP Server

   httpd.exe -k install

2. When the service is running, call http://localhost in your browser to test the server. You should get a website saying "It works".
3. The mod_jk extension is not part of the standard delivery, so it needs to be installed separately:
   Copy the file mod_jk.so to the subfolder modules in your Apache installation, for example c:/Apache24/modules.
4. Open the file httpd.conf located in the subfolder conf, for example: C:/Apache24/conf/http.conf.

5. Add the following line in the file, to activate the module:

   LoadModule jk_module modules/mod_jk.so

6. Save the file.

7. Restart the Apache HTTP Service.

On the Apache HTTP Server, do the following to get the Load balancer running:

1. Create a workers.properties file and place it together with httpd.conf in c:\apache24\conf. Edit the host name and port for Apache JServ Protocol (AJP), in this example 8009, to your corresponding environment.
   
   The file workers.properties does the configuration of the different Tomcat nodes (in most cases you will have two nodes). It holds some very basic parameters like Tomcat host names, ports, but also a lot of additional things (like load balancing factor sticky session setup etc) can be defined here. The following example describes the most basic setup to get the system running, depending on the customers’ requirements it might be necessary to fine-tune this according to the official mod_jk documentation.

   Example: workers.properties

   # workers to contact, that's what you have in your httpd.conf 
   worker.list=loadbalancer,status 
   
   
   #setup node1 
   worker.node1.port=8009 
   worker.node1.host=myTomcatHost.node1 
   worker.node1.type=ajp13 
   worker.node1.lbfactor=50 
   
   
   #setup node2 
   worker.node2.port=8009 
   worker.node2.host= host=myTomcatHost.node2 
   worker.node2.type=ajp13 
   worker.node2.lbfactor=50 
   
   
   #setup the load-balancer 
   worker.loadbalancer.type=lb 
   worker.loadbalancer.balance_workers=node1,node2 
   worker.loadbalancer.sticky_session=true 
   worker.loadbalancer.sticky_session_force=true 
   worker.loadbalancer.set_session_cookie=true 
   
   
   # Status worker for managing load balancer 
   worker.status.type=status

2. Do the following updates in the file httpd.conf:

   1. Add the following lines to the httpd.conf, to set up the mod_jk configuration for the load balancer, pointing to the corresponding file workers.properties:

      Example: httpd.conf

      JkWorkersFile C:/Apache24/conf/workers.properties 
      
      
      JkShmFile C:/Apache24/logs/httpd/mod_jk.shm 
      JkLogFile C:/Apache24/logs/httpd/mod_jk.log 
      JkLogLevel debug 
      JkLogStampFormat "[%a %b %d %H:%M:%S %Y] " 
      
      
      #global JkMounts - you can remove them when using virtual hosts 
      JkMount /prime_explorer/** loadbalancer 
      JkMount /prime_ussp/** loadbalancer 
      
      
      # optionally add the status mount point 
      # JkMount /jkmanager/* status

      This example assumes that PRIME Explorer and USSP are deployed as prime_explorer and prime_ussp webapps on both Tomcats.
      

      The jkmanager is deactivated in this setup. To activate it, remove the # in the beginning of the line. Consider that the jkmanager should be restricted only to admins, for example by using a certain authenticate port. The jkmanager allows to maintain the nodes.

   2. If the PRIME service should run on certain ports, for example in an HTTPS environment, set up a virtual host in httpd.conf.
      The following example describes a setup for HTTPS.
      

      Example: virtual host in httpd.conf

      Listen 444 
      NameVirtualHost *:444 
      <VirtualHost *:444> 
      	ServerName nexusprime.local 
      	SSLEngine on 
      	SSLCertificateFile "c:/apache24/conf/primeServerCert.cer" 
      	SSLCertificateKeyFile "c:/apache24/conf/ primeServerCert.key" 
      #SSLVerifyClient require 
      #SSLVerifyDepth 1 
      #SSLCACertificateFile "c:/apache24/conf/ primeTrustedCA.cer" 
      
      
      JkMount /prime_explorer/** loadbalancer 
      JkMount /prime_ussp/** loadbalancer 
      #JkMount /jkmanager/* status 
      
      
      </VirtualHost>

      This setup provides an HTTPS Connection on Port 444. For client authentication you need to activated the three lines marked with #. If you use client certificates, you might want to remove the global JkMount entries shown in the first example.
      
      When using SSL client authentication, you might want to forward the certificates to the PRIME system. Please check the AJP manual for the corresponding parameters.

All Tomcat nodes must have exactly the same setup. Especially the deployment of the applications (in webapps) and the server-side configuration in these applications must be the identical, for example database.properties and log4j.xml. It is also a good idea to keep server.xml and Java OS Environment identical.

Also, communication to subsystems must be available in the same way on each node, for example File Export, LDAP connection, and PKI connections.

To install identical Tomcat nodes:

1. Install a complete PRIME system on one node, including Tomcat, Java, PRIME applications, and database connection.
2. Copy the setup from the first node to other nodes, to make sure that all components are exactly the same on all nodes.
3. Verify that each PRIME instance on each node works properly on its own.

To configure the node name and activate the AJP connector, do the following for each node:

1. Open server.xml.

2. In server.xml, go to the Engine element. Edit the name in the parameter jvmRoute, to tell Tomcat which node to listen to.
   
   The node names are defined in workers.properties. In the example above it is node1 and node2.

   Example: Engine element in server.xml

   <Engine name="Catalina" defaultHost="localhost" jvmRoute="node1">

3. The AJP Connector itself is normally also activated by default on Tomcat. In server.xml, verify that the following Connector entry is present, and that :

   Example: Connector element in server.xml

   <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

4. If you want to avoid that someone can access one of the Tomcat nodes directly, deactivate all the other HTTP- or HTTPS-based connectors on the Tomcats.

5. When the Apache HTTP Server and the Tomcats are successfully configured, the Loadbalancer is ready to use.

   It doesn’t matter in which order the services are started, the connections are established or re-established on demand.
   

   To see the status of each node, check the jkmanager.