TIBCO Spotfire Server 3.2.2 - TIBCO Product Documentation

Load Balancing
7 Load Balancing
This chapter explains the concept of load balancing in a clustered environment, and
how to set this up if you are running multiple Spotfire Servers in a cluster.
7.1 Overview
Load balancing is a technique for spreading the workload between two or more
computers.
In a clustered environment, each Spotfire client connects to a single network host, a
load balancer, which redirects calls to an available Spotfire Server. It is important that
the load balancer is able to redirect follow-up connections from the client to the same
Spotfire Server for the duration of the user session (session affinity). It must also be
able to detect when a Spotfire Server is unavailable, such as when maintenance is
being performed, and stop directing traffic to that server. When the Spotfire Server
becomes available again, the load balancer must start directing calls to it again. If you
wish to implement your own load balancing solution, these requirements must be met,
with special emphasis on session affinity, without which communication between
clients and servers will not work.
The rest of this chapter assumes that you are using a load balancing solution based on
Apache httpd with the mod_jk module enabled. Because the Spotfire Server is
implemented as a Tomcat Service, and therefore supports the AJP (Apache JServ
Protocol) protocol, this technology provides a good starting point for achieving a load
balanced Spotfire system.
To set up load balancing, configuration needs to be done on all the cluster nodes, as
well as on the load balancer itself.
7.2 Prerequisites
• At least two Spotfire Servers need to be installed and configured.
• Apache httpd and the mod_jk module need to be installed on the load balancer.
• Optional: If NTLM authentication is used, the mod_auth_sspi module needs to
be enabled in Apache httpd.
7.3 Cluster Node Configuration
Each Spotfire Server is prepared for communication with a load balancer on
installation. You do not need to change anything on the servers. If you are well
acquainted with load balancing and want to change any default settings, they are all set
in the file server.xml. See the section “Server.xml” on page 135 for more information
about this file.
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