Replication Function

Overview

SIP Servlet Engine provides the replication function to realize high availability (HA). When SSE is running on multiple managed servers in a WebLogic Server clustered environment and the same SIP application is running on each SSE, even if a server instance fails, another server instance can continue SIP application processing.

SSE V3.0 implements this replication function by making use of the HTTP session replication function provided in WebLogic Server 8.1. (For more information about the HTTP session replication function, see Using WebLogic Server Clusters.) An application session (and its SIP session) is associated with an HTTP session and internal information of the application session is held by the HTTP session. When a failover occurs, SSE retrieves the internal information of the application session from the HTTP session and restores the application session.

An application session and an HTTP session are associated by using each session ID. This mapping information is stored in a repository. SSE V3.0 can use a file or database as a repository.

A replica of the application session is created when its response to an initial request is received. Therefore, no transaction is restored when a failover occurs.

Replication process is performed when each doXxx method has completed. Therefore even when a server failed during doXxx method operation, the server on which a failover has occurred can continue processing.

Objects Which Can be Replicated

The objects which can be replicated in the SSE replication function are as follows:

SIP Session
Application Session
Servlet Timer
SIP Servlet Request
SIP Servlet Response
Serializable Object

But if an SIP servlet request or SIP servlet response is set as an attribute of another SIP servlet request or SIP servlet response, its replica can not be created.

SSE Clustering Configuration

To configure to use SSE in a WLS clustered environment, you need to configure WebLogic Server (config.xml) and SSE (sipserver.xml). This section describes how to configure the sipserver.xml. For information about configuring WebLogic Server, see Configuration for Extending System.

You can configure the following settings in the <param-name> tag of the <container-param> tag in the sipserver.xml.

ReplicationRepositoryType: Specify the type of the repository. When you want to use a file repository, specify "file" and when you want to use a database repository, specify "db".
ReplicationRepositoryStorage: For a file repository, specify the directory of the repository and for a database repository, specify the data source name.
ReplicationUnit: Specify the unit of sessions associated with HTTP sessions. When application sessions are associated with HTTP sessions, specify "application" and when application sessions and SIP sessions are associated with different HTTP sessions, specify "session".

Last Modified:Mon Dec 27 10:00:18 JST 2004