Visualization Platform client load balancing
Visualization Platform client supports two kinds of load balancing, as illustrated in Figure 1‑1, to ensure high availability and to distribute tasks for efficient processing:
Figure 1‑1 Load-balancing architecture for Visualization Platform client
*Actuate Message Distribution service (MDS) balances the request load among BIRT iHub machines in an BIRT iHub cluster.
The Message Distribution service eliminates the need for a third-party network load balancer in front of the BIRT iHub tier. iHub determines which machines in a cluster have MDS running and detects when the MDS machines go offline. MDS distributes the load among the available servers and does not attempt to send a request to an offline machine.
*Clustered Visualization Platform client machines can use a third-party application to balance the load among the application servers.
Deploying a load balancer for an BIRT iHub cluster
To deploy a load balancer or proxy layer in front of the BIRT iHub tier, disable the Actuate load-balancing support by setting the MDS_ENABLED configuration parameter to False in the web.xml Visualization Platform client configuration file. For EAR and WAR installations, this must be done before deployment. When installing as a Windows service, you can make the configuration change after installing.
Using a cluster of application servers
If the application servers running Visualization Platform client support session state management, you can configure Visualization Platform client and the application servers to share and maintain a web browsing session state across a cluster of Visualization Platform client instances. Configuring the application servers to track the state of each Visualization Platform client instance supports reusing authentication information. In other words, you can log in to a Visualization Platform client instance and send a request using another Visualization Platform client instance without logging in again using the second instance.
If you do not use an application server to track session state information, managing the session state is fast, but you lose a user’s state information when you restart Visualization Platform client or your application server.
Sharing session state information takes advantage of the application servers’ failover features. If a user is on a cluster application server running Visualization Platform client and that application server fails, another application server running Visualization Platform client can manage the user’s session.
An application server works with one or more database servers to manage session state information. All application servers must have access to the database server to store and retrieve session state information. For specific information about configuring your installation, see your application server documentation.