15.3 Configuring a Web Application to Provide High Availability Functionality for Your Vibe Site

After Novell Vibe is installed and running on multiple servers, you must provide additional software to provide high availability functionality. Because Vibe is based on Tomcat, you can use software that provides high availability for Tomcat.

  1. Install and configure one of the following Web applications to provide high availability for your Vibe site:

  2. Configure the Web application to establish the Vibe site URL, which then stays constant for Vibe users regardless of which Vibe server they access at any given time.

  3. Start the Web application with its new configuration settings.

  4. Test your Vibe site for high availability.

    • If you are using Apache Web server, Linux Virtual Services, or Microsoft Internet Information Services, users can immediately log in to the Vibe site again after a failover has occurred. The connection between the user’s browser and the Vibe site is maintained as the failover occurs.

    • If you are using Novell Access Manager, users must start a new browser session, then log in to the Vibe site after a failover has occurred. They cannot log in again from the same browser session because the connection between the user’s browser and the Vibe site must be reestablished after the failover.

The following sections provide examples of how to configure the Web applications:

15.3.1 Configuring Tomcat and Apache as a Load Balancer

The following example configuration uses the balancer module built into the newer Apache (version 2.2.4 and later) Web server. It is based on a widely used sticky session technique. Novell Vibe does not support session sharing/replication among Tomcat instances.

If you are using Novell Access Manager as described in Section 9.8, Configuring Single Sign-On with Novell Access Manager, you do not need to configure Tomcat and Apache to load balance as described in this section, because Access Manager provides this service.

NOTE:When you update your Vibe system, these settings are not preserved. You must redefine these settings each time you update your Vibe system.

To configure Tomcat and Apache to load balance:

  1. Install the Apache Web server on one server.

  2. Edit the httpd.conf file in the Apache installation:

    The httpd.conf file is located in the conf subdirectory in the Apache installation.

    1. Locate and uncomment the following lines:

      LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so

    2. Append the following section to the httpd.conf file, providing a BalancerMember line for each jvmRoute value in a Tomcat server.xml file. 

      <Location /balancer-manager>
   SetHandler balancer-manager
   Order deny,allow
   Deny from all
   Allow from 127.0.0.1
</Location>
<Proxy balancer://cluster_name>
   BalancerMember ajp://vibe_server_1:8009 route=worker1
   BalancerMember ajp://vibe_server_2:8009 route=worker2
</Proxy>
<Location />
   ProxyPass balancer://cluster_name/ stickysession=JSESSIONID
</Location>

      The values that you specify for the route setting (for example, worker1, worker2, etc.) must exactly match the values that you specify as the JVM Route setting during the Vibe installation, as described in Section 15.2, Installing the Vibe Software on Multiple Servers.

    3. Save the httpd.conf file.

  3. Reconfigure each Vibe server in the cluster so that each server has the same hostname as the Apache Web server.

    For information on how to reconfigure your Vibe server, see Section 11.0, Setting Configuration Options after Installation.

  4. Restart Tomcat and Apache.

HINT:For enhanced performance when using the Internet Explorer browser to access a Vibe system that is using Apache as an SSL reverse-proxy server, change the Apache SSL exclusion regular expression configuration from the following:

SetEnvIf User-Agent ".*MSIE.*" \
nokeepalive ssl-unclean-shutdown \
downgrade-1.0 force-response-1.0

to the following:

SetEnvIf User-Agent ".*MSIE [1-5].*"
nokeepalive ssl-unclean-shutdown
downgrade-1.0 force-response-1.0

SetEnvIf User-Agent ".*MSIE [6-9].*"
ssl-unclean-shutdown

15.3.2 Configuring Linux Virtual Server as a Load Balancer

Consult the following online sources for instructions for setting up Linux Virtual Server as a load balancer for your Novell Vibe site: