Siebel Store-and-Forward Messaging Guide for Handheld > Installation and Configuration of Siebel Store-and-Forward Messaging > Setting Up Load Balancing for Store-and-Forward Messaging >

About the Siebel Load Balancer

Siebel Store-and-Forward Messaging provides a load balancing framework that allows messages to be received, not only by the server on which the handheld application is registered, but other servers as well. With load balancing deployed, Store-and-Forward Messaging can use any available server where the Handheld Application Server is running. During inbound user queue processing, if an error occurs, the message will not be removed from the queue but will be retried.

The Siebel Load Balancer works as follows:

• The Siebel Session Manager reads the content of a virtual hosts file and dispatches client requests to the servers defined in that file in a round-robin fashion. For example, if there are three Siebel Servers, A, B, and C, the requests are processed one by one by servers A, B, then C repeatedly.
• If SiebelServA is down, the system retries a connection request sent to SiebelServA automatically. A retry occurs when the system is trying to establish a connection. If a connection is established and broken in the middle of a session, no retry is attempted.
• If the session manager attempts to connect to SiebelServA and SiebelServA is unavailable, the session manager first retries connecting to SiebelServA. If it cannot establish a connection on this retry, the next retry goes to SiebelServB. If the session manager cannot establish a connection with SiebelServB, subsequent retries go to A, B, A, B, and so on, until a connection to either server can be established.
• There is no guarantee that the Session Manager will always succeed in establishing a connection with the server through any given number of retries. If the Session Manager does not succeed, it enters an error message in the log file. For more information about retries, see 477835.1 (Doc ID) on My Oracle Support. This document was previously published as Siebel Technical Note 540.
• If SiebelServA is up again, the Session Manager detects this and resumes routing requests to that server.

In planning for load balancing, it is recommended that you first decide how many server machines will be used for Load Balancing, then install the required Siebel server components on the server machines, and finally configure the load balancing setup before any Siebel Handheld connects.